farmknowledge.info · publication 3451 • online with photos at • uc statewide integrated pest...

Publication 3451 • Online with photos at http://www.ipm.ucanr.edu/PMG/selectnewpest.nectarine.html

• UC Statewide Integrated Pest Management Program

Nectarine June 2017 PEST MANAGEMENT GUIDELINES FOR AGRICULTURE

Contents (Dates in parenthesis indicate when each topic was updated) Nectarine Year-round IPM Program (Reviewed 6/10) ............................................................................................................................ iv

General Information (Section reviewed 6/10) ............................................................................................................................................ 1 Dormant Shoot Sampling (6/10) ................................................................................................................................................................ 1 Pheromone Traps (6/10) ............................................................................................................................................................................. 2 Early-Season Monitoring (6/10) ................................................................................................................................................................. 3 Shoot Strike Monitoring (6/10) .................................................................................................................................................................. 4 Fruit Sampling (6/10) .................................................................................................................................................................................. 5 Relative Impact of The Timing of Pesticide Applications on Natural Enemies (6/10) ...................................................................... 6 Relative Toxicities of Insecticides and Miticides Used in Nectarines to Natural Enemies and Honey Bees (8/15) ............................................................... 7 General Properties of Fungicides Used in Nectarines (8/15) ................................................................................................................ 9 Fungicide Efficacy (6/17) .......................................................................................................................................................................... 10 Most Effective Treatment Timing for Key Diseases (6/17) .................................................................................................................. 11 Fungicide Resistance Management (6/17) ............................................................................................................................................. 12

Insects and Mites (Section reviewed 6/10) ................................................................................................................................................ 14 Black Peach Aphid (8/15) ......................................................................................................................................................................... 14 Brown Mite (8/15) ...................................................................................................................................................................................... 15 European Fruit Lecanium (8/15) ............................................................................................................................................................. 17 European Red Mite (8/15) ........................................................................................................................................................................ 18 Fruittree Leafroller (8/15) ......................................................................................................................................................................... 20 Katydids (8/15) ........................................................................................................................................................................................... 23 Obliquebanded Leafroller (8/15) ............................................................................................................................................................. 25 Omnivorous Leafroller (8/15) .................................................................................................................................................................. 29 Oriental Fruit Moth (8/15) ........................................................................................................................................................................ 32 Pacific Flatheaded Borer (8/15) ................................................................................................................................................................ 36 Peach Silver Mite (8/15) ............................................................................................................................................................................ 37 Peach Twig Borer (8/15) ............................................................................................................................................................................ 38 Peachtree Borer (8/15) ............................................................................................................................................................................... 44 Plant Bugs (8/15) ........................................................................................................................................................................................ 45 Prune Limb Borer and American Plum Borer (8/15) ............................................................................................................................ 48 San Jose Scale (8/15) .................................................................................................................................................................................. 49 Shothole Borer (8/15) ................................................................................................................................................................................. 53 Stink Bugs (8/15) ........................................................................................................................................................................................ 54 Webspinning Spider Mites (8/15) ............................................................................................................................................................ 56 Western Flower Thrips (8/15) .................................................................................................................................................................. 60

Diseases (Section reviewed 6/10) ................................................................................................................................................................ 62 Armillaria Root Rot (Oak Root Fungus) (8/15) ..................................................................................................................................... 62 Bacterial Canker (8/15) .............................................................................................................................................................................. 64 Brown Rot Blossom and Twig Blight (8/15) .......................................................................................................................................... 66 Crown Gall (8/15) ...................................................................................................................................................................................... 68 Jacket Rot (8/15) ......................................................................................................................................................................................... 69 Peach Leaf Curl (8/15) ............................................................................................................................................................................... 71 Phytophthora Root and Crown Rot (8/15) ............................................................................................................................................. 73 Powdery Mildew (8/15) ............................................................................................................................................................................ 75 Ripe Fruit Rot (8/15) .................................................................................................................................................................................. 77 Rust (8/15) ................................................................................................................................................................................................... 79 Scab (8/15) ................................................................................................................................................................................................... 81 Shot Hole Disease (8/15) ........................................................................................................................................................................... 83 Verticillium Wilt (8/15) ............................................................................................................................................................................. 85

Nematodes (Section reviewed 6/10) ........................................................................................................................................................... 86

UC IPM Pest Management Guidelines - NECTARINE

January 2016 ii

Weeds (Section reviewed 6/10) .................................................................................................................................................................... 90 Integrated Weed Management (8/15) ..................................................................................................................................................... 90 Weed Management in Organic Orchards (6/10) ................................................................................................................................... 94 Special Weed Problems (6/10) ................................................................................................................................................................. 97 Common and Scientific Names of Weeds (6/10) .................................................................................................................................. 99 Susceptibility of Winter Weeds to Herbicide Control (6/10) ............................................................................................................ 101 Susceptibility of Spring and Summer Weeds in Nectarines to Herbicide Control (6/10) ............................................................. 102 Herbicide Treatment Table (8/15) ......................................................................................................................................................... 104 Precautions for Using Pesticides ............................................................................................................................................................ 109


January 2016 iii

Authors Insects and Mites: K. R. Day, UCCE Tulare Co.; K.Tollerup, UC IPM Program, Kearney Agricultural Center,

Parlier Diseases: J. E. Adaskaveg, Plant Pathology, UC Riverside; R. A. Duncan, UCCE Stanislaus Co.; K. R. Day, UCCE

Tulare Co. Nematodes: B. B. Westerdahl, Nematology, UC Davis Weeds: J. A. Roncoroni, UCCE Napa Co.; S. D. Wright, UCCE Tulare Co. Crop Leadership Team: K. R. Day, UCCE Tulare Co. (crop team leader); K.Tollerup, UC IPM Program, Kearney

Agricultural Center, Parlier (IPM facilitator); R. DeBiase, UC IPM Program (coordinator); R. A. Duncan, UCCE Stanislaus Co; J. A. Roncoroni, UCCE Napa Co.; B. B. Westerdahl, Nematology, UC Davis

Acknowledgments for contributions Year Round IPM Program and Corresponding General Information sections: W. J. Bentley, UC IPM Program,

Kearney Agricultural Center, Parlier; S. Johnson, Pomology, Kearney Agricultural Center, Parlier Insects and Mites: W. J. Bentley, UC IPM Program, Kearney Agricultural Center, Parlier; R. E. Rice, Kearney

Agricultural Center, Parlier Diseases: W. D. Gubler, Plant Pathology, UC Davis; B. L. Teviotdale, Kearney Agricultural Center, Parlier Nematodes: R. A. Duncan, UCCE Stanislaus Co.; U. C. Kodira, Plant Pathology, UC Davis; M. V. McKenry,

Kearney Agricultural Center, Parlier; Weeds: K. Hembree, UCCE Fresno Co.; W. T. Lanini, Weed Science/Plant Sciences, UC Davis; A. Shrestha, UC

IPM Program, Kearney Agricultural Center, Parlier; About this publication Produced and edited by: UC Statewide IPM Program University of California, Agriculture and Natural Resources Guidelines Coordinator: R. DeBiase Production: F. Rosa

This publication has been anonymously peer reviewed for technical accuracy by University of California scientists and other qualified professionals. This review process was managed by the ANR Associate Editor for Agricultural Pest Management.

The UC IPM Pest Management Guidelines are available from: • Online: http://www.ipm.ucanr.edu • UC Cooperative Extension County Offices • University of California

ANR Communication Services Richmond, CA 94804 510-665-2195; 800-994-8849

Updates: These guidelines are updated regularly. Check with your University of California Cooperative Extension Office or the UC IPM Web site for information on updates.

Note to readers: These guidelines represent the best information currently available to the authors and are intended to help you in making the best choices for an IPM program. Not all formulations or registered materials are mentioned. Always read the label and check with local authorities for the most up-to-date information regarding registration and restrictions on pesticide use. Check with your agricultural commissioner for latest restricted entry intervals.

To be used with UC ANR Publication 3389, Integrated Pest Management for Stone Fruit


(6/10) Nectarine Year-Round IPM Program Annual Checklist Download this checklist at www.ipm.ucanr.edu/FORMS/

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Nectarine Year-round IPM Program (Reviewed 6/10) ANNUAL CHECKLIST These practices are recommended for a monitoring-based IPM program that enhances pest control and reduces environmental quality problems related to pesticide use. Water quality becomes impaired when pesticides and sediments move off-site and into water. Air quality becomes impaired when volatile organic compounds (VOCs) move into the atmosphere. Each time a pesticide application is considered, review the Pesticide Application Checklist at the bottom of this page for information on how to minimize water quality problems. This year-round program covers the major pests of nectarines. Details on carrying out each practice and information on additional pests can be found in the guidelines. Track your progress through the year with the annual checklist form. All photo identification pages and example monitoring forms can be found online at: http://www.ipm.ucanr.edu/FORMS/

ü Done Dormancy to delayed-dormancy Mitigate pesticide effects on air and water quality.

Apply fungicide treatments as needed according to PMGs: • Peach leaf curl • Shot hole disease

Manage orchard floor vegetation: • Survey weeds and keep records (example form available online). • Manage weeds with pre- or postemergence herbicides or nonchemically in organic orchards. • Mow any resident vegetation very close to ground.

Make an oil treatment for scales and European red and brown mite eggs. • If you saw increasing damage from scales last year, take a dormant shoot sample to see if an insect

growth regulator should be added to the oil treatment.

Treat peach twig borer and obliquebanded leafroller with environmentally sound material or delay treatment until bloom.

Other pests you may see: • Armillaria root rot • Fruittree leafroller egg masses • Pocket gophers

• Stink bugs • Tree borers • Voles

ü Done Bloom (green tip to petal fall) Mitigate pesticide effects on air and water quality.

Put out pheromone traps for: • Oriental fruit moth (February 15) • Omnivorous leafroller (February 20) • San Jose scale (February 25) Check traps and keep records (example form available online).

If using mating disruption for oriental fruit moth, place dispensers in orchard after first moth is caught but no later than March 5.

Examine flower clusters and leaves for: • Western flower thrips • Katydids • Peach twig borer • Fruittree leafroller • Obliquebanded leafroller



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ü Done Bloom (green tip to petal fall) Mitigate pesticide effects on air and water quality.

Monitor for other pests, including stink bugs and plant bugs, as well as known invasive pests (spotted wing drosophila, light brown apple moth).

When rainy conditions promote disease, time fungicide treatment according to PMGs: • Brown rot at 20 to 40% bloom and full bloom. • Jacket rot treatment at full bloom. • Powdery mildew treatment at petal fall. • Scab, if orchard has a history of this disease.

Monitor for diseases: • Rust

¢ Monitor twig cankers beginning late March. ¢ Treat with fungicide if needed according to PMG.

• Shot hole ¢ Fruiting structures in leaf lesions as long as weather is wet. ¢ Manage if needed according to PMG.

Observe the orchard for vertebrates and manage as necessary: • Gophers • Ground squirrels

Other pests you may see: • Armillaria root rot (oak root fungus) • Bacterial canker • Phytophthora crown and root rot

ü Done Fruit development (petal fall to harvest) Mitigate pesticide effects on air and water quality..

Put up pheromone traps for: • Peach twig borer (March 20) • Obliquebanded leafroller (April 15)

Continue to monitor for western flower thrips through jacket drop.

Monitor shoot strikes for damage from oriental fruit moth and peach twig borer. • Keep records (example form available online). • Manage if needed according to PMGs.

If wet weather persists, continue to monitor for rust: • Manage if needed according to PMG.

If orchard has a history of scab: • Treat 3 weeks after full bloom. • Treat again 2 weeks later if scab was severe the previous year.



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ü Done Fruit development (petal fall to harvest) Mitigate pesticide effects on air and water quality..

Take sweep samples in orchards and adjacent crops and weedy areas, beginning from early April to early June for: • Plant bugs (Lygus and Calocoris) • Katydids • Stink bugs Manage if needed according to PMG.

Sample fruit damage every other week after color break. Monitor powdery mildew and treat if needed according to PMG.

Manage orchard floor: • Survey weeds and keep records (example form available online). • Spot treat weeds if needed according to PMG.

Monitor spider mites from late April through August: • For best evaluation, conduct two 5-minute searches and record results (example form available

online). • Manage if needed according to PMG.

Select leaf samples in late June through July to analyze for nutrients. Pay particular attention to nitrogen, potassium, and some of the micronutrients such as zinc and boron. • Take 60 to 80 mid-shoot leaves from moderately vigorous fruiting shoots.

If rain is predicted during the last 4 weeks before harvest, treat for ripe fruit rot.

Other pests you may see: • Armillaria root rot • Bacterial canker • Black peach aphid • Peach silver mite

• Phytophthora root and crown rot • Scab • Tree borers • Verticillium wilt

ü Done Harvest Mitigate pesticide effects on air and water quality.

Monitor for ripe fruit rot and treat if rain is predicted. Take a harvest sample to determine pest damage (example form available online).

ü Done Postharvest Mitigate pesticide effects on air and water quality.

In early harvest orchards continue to watch for: • Shoot strikes to determine if oriental fruit moth populations are building. • Webspinning spider mites.

Remove fruit remaining in trees to reduce brown rot inoculum and prevent shoot death.

If surface water runoff is an issue, particularly near waterways, consider the use of cover crops or resident vegetation.



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ü Done Pesticide application checklist

When planning for possible pesticide applications in an IPM program, consult the Pest Management Guidelines, and review and complete this checklist to consider practices that minimize environmental and efficacy problems

ü Choose a pesticide from the Pest Management Guidelines for the target pest, considering:

• Impact on natural enemies and pollinators. For more information see Protecting Natural Enemies and Pollinators at http://www.ipm.ucanr.edu/mitigation/protect_beneficials.html.

• Potential for water quality problems using the UC IPM WaterTox database. See www.ipm.ucanr.edu/TOX/simplewatertox.html.

• Impact on aquatic invertebrates. For more information, see Pesticide Choice, UC ANR Publication 8161 (PDF), http://anrcatalog.ucdavis.edu/pdf/8161.pdf.

• Chemical mode of action, if pesticide resistance is an issue. For more information, see Herbicide

Resistance: Definition and Management Strategies, UC ANR Publication 8012 (PDF), http://anrcatalog.ucdavis.edu/pdf/8012.pdf.

• Endangered species that may be near your site. Find out using the Department of Pesticide Regulation's PRESCRIBE program. (http://www.cdpr.ca.gov/docs/endspec/prescint.htm)

ü Before an application Ensure that spray equipment is properly calibrated to deliver the desired pesticide amount for optimal

coverage. See www.ipm.ucanr.edu/training/incorporating-calibration.html. Use appropriate spray nozzles and pressure to minimize off-site movement of pesticides.

Avoid spraying during these conditions to avoid off-site movement of pesticides. • Wind speed over 5 mph • Temperature inversions • Just prior to rain or irrigation (unless it is an appropriate amount, such as when incorporating a soil-

applied pesticide) • At tractor speeds over 2 mph

Identify and take special care to protect sensitive areas (for example, waterways or riparian areas) surrounding your application site.

Review and follow labeling for pesticide handling, personal protection equipment (PPE) requirements, storage, and disposal guidelines.

Check and follow restricted entry intervals (REI) and preharvest intervals (PHI).

ü After an application Record application date, product used, rate, and location of application. Follow up to confirm that treatment was effective.



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ü Done Pesticide application checklist ü Consider water management practices that reduce pesticide movement off-site.

Consult relevant publications:

• Reducing Runoff from Irrigated Lands: Orchard Floor Management Practices to Reduce Erosion and Protect Water Quality, UC ANR Publication 8202 (PDF), http://anrcatalog.ucdavis.edu/pdf/8202.pdf.

• Reducing Runoff from Irrigated Lands: Causes and Management of Runoff from Surface Irrigation in Orchards, UC ANR Publication 8214 (PDF), http://anrcatalog.ucdavis.edu/pdf/8214.pdf.

• Protecting Surface Water from Sediment-Associated Pesticides in Furrow-Irrigated Crops, UC ANR Publication 8403 (PDF), http://anrcatalog.ucdavis.edu/pdf/8403.pdf.

Consult the Department of Pesticide Regulation Groundwater Protection Program (GWPA) Web site for pesticide information and mitigation measures. (http://www.cdpr.ca.gov)

Install an irrigation recirculation or storage and reuse system. Redesign inlets into tailwater ditches to reduce erosion.

Use drip rather than sprinkler or flood irrigation.

Limit irrigation to amount required using soil moisture monitoring and evapotranspiration (ET). For more information, see Reducing Runoff from Irrigated Lands: Understanding Your Orchard's Water Requirements, UC ANR Publication 8212 (PDF), http://anrcatalog.ucdavis.edu/pdf/8212.pdf.

Consider using cover crops.

Consider vegetative filter strips or ditches. (For more information, see Vegetative Filter Strips, UC ANR Publication 8195 (PDF), http://anrcatalog.ucdavis.edu/pdf/8195.pdf.)

Apply polyacrylamides in furrow and sprinkler irrigation systems to prevent off-site movement of sediments.

ü Consider practices that reduce air quality problems.

When possible, reduce volatile organic compound (VOC) emissions by decreasing the amount of pesticide applied, choosing low-emission management methods, and avoiding fumigants and emulsifiable concentrate (EC) formulations.

For more about mitigating the effects of pesticides, see the Mitigation page.


(6/10) Dormant Shoot Sampling 1 Online with photos at http://www.ipm.ucanr.edu/PMG/selectnewpest.nectarine.html

General Information (Section reviewed 6/10)

DORMANT SHOOT SAMPLING (6/10) Dormant shoot sampling is used to determine the need for a dormant treatment for the control of San Jose scale, European fruit lecanium, and mite eggs (brown mite and European red mite). HOW TO SAMPLE (View photos online for identification) • Take a sample between late November and mid-January. • Randomly select 20 trees from each varietal block in the orchard. • Choose 5 shoots randomly from the inside of each tree's canopy near the main scaffolds for a total of 100

shoots. • Clip off a 3-inch section from the basal portion of the shoot that contains both 1- and 2-year old wood. • Using a hand lens or binocular microscope, examine the section of the shoot and note the presence or absence

of scales and parasitized scales and mite eggs on a sampling form (example form available online). It is not necessary to count the number of individual insects or mite eggs present, just identify the pest and record whether it is present or not.

• Note if scales have been parasitized. A parasitized scale can be distinguished from a live scale by a small hole in the top of the scale covering. Parasitized European fruit lecanium scales turn black. If a large number of scales have been parasitized, minimize the use of insecticides during the growing season, and use those that are not harmful to parasites so that naturally occurring parasite populations will not be destroyed.

• Use the Dormant Treatment Decision Table below to determine if treatment is required and what to spray. DORMANT TREATMENT DECISION TABLE (% infested shoots)

TREATMENT THRESHOLD Treatment

European fruit lecanium 24% and below No spray Over 24% Oil only

Overwintering mite eggs (brown mite and European red)

Below 20% No spray 20% and over Oil only

San Jose scale

Harvested before June 15

Harvested after June 15

Below 20% Below 5% No treatment 20-60% 5-10% Oil at 6 gal/acre Over 60% Over 10% Oil at 2-6 gal/acre plus insect

growth regulator1

1 Using oil at the 4-6 gal rate will help prevent development of resistance to the IGR. If oil is used at the 2 gal rate, do not use the IGR in consecutive years to prevent resistance development.

CHOICE OF PESTICIDES Choice of pesticide depends on which pests are present at damaging levels and when treatment is being applied. During the dormant season, oils alone are effective against the white cap and black cap stages of San Jose scale, which are present at this time, and will also control populations of mite eggs and provide moderate control of fruittree leafroller eggs. Only the highest levels of San Jose scale will require addition of an insect growth regulator. Other pests such as peach twig borer and obliquebanded leafrollers will not be controlled by oil during the dormant season. Environmentally sound insecticides such as Bacillus thuringiensis, chlorantraniliprole (Altacor), diflubenzuron (Dimilin), and methoxyfenozide (Intrepid), however, applied at bloom will control peach twig borer and leafrolling caterpillars. Combining these bloom time treatments along with a dormant oil application for scales, mite eggs, and leafroller eggs is a good IPM strategy for many orchards. Organophosphates applied during the dormant season for peach twig borer are particularly vulnerable to run-off into waterways, are no more effective than reduced risk products, and should be avoided. Never spray before an expected rainfall. If you wish to treat peach twig borer during the dormant season, consider an environmentally sound insecticide such as spinosad, spinetoram, or diflubenzuron. See the peach twig borer guideline.


(6/10) Pheromone Traps 2 Online with photos at http://www.ipm.ucanr.edu/PMG/selectnewpest.nectarine.html

PHEROMONE TRAPS (6/10) In nectarines, pheromone traps are used to monitor adult emergence and flights of San Jose scale and certain moths including oriental fruit moth, omnivorous leafroller, peach twig borer, and obliquebanded leafroller. Use the information obtained from trap catches to schedule control actions when used in conjunction with degree-day calculations. The traps are used to establish a biofix—an identifiable point in the life cycle of the pest at which you can begin degree-day accumulation or take a management action. For example, the biofix for peach twig borer is the date that the first adult moth of each generation is caught. GENERAL GUIDELINES FOR USING PHEROMONE TRAPS • Place traps in each orchard for which you need to make pest management decisions. • Traps should be placed in orchards by the dates indicated in the table below. • Use at least 2 traps per block for moths, and 3 or 4 per block for San Jose scale. • Distribute the traps uniformly throughout the orchard and use the same locations each year. • Place additional traps in hot spots for specific pests. • Hang traps 6 to 8 feet high, 1 to 3 feet inside the canopy in the north quadrant of the tree, in the shade, and at

least 5 trees in from the edge of the orchard. • Check traps twice a week until the biofix is established; thereafter, check traps weekly. • Remove trapped insects from the trap bottom after you count and record trap catches on a monitoring form

(example form available online). • Replace trap bottoms monthly or when they become covered with debris. • Follow manufacturer's recommendations for replacing pheromone dispensers. • Store pheromone dispenser in a refrigerator or freezer.

WHEN TO PUT OUT TRAPS IN THE SAN JOAQUIN VALLEY

Pest Where and When Importance Oriental fruit moth February 15 Detect first moth emergence to know when to start

degree-day accumulation

San Jose scale February 25 Detect males to start degree-day accumulation

Omnivorous leafroller February 20 Detect moth emergence to start degree-day accumulation

Peach twig borer March 20

Detect moth emergence to start degree-day accumulation

Obliquebanded leafroller April 15 Detect moth emergence to start degree-day accumulation


(6/10) Early-Season Monitoring 3 Online with photos at http://www.ipm.ucanr.edu/PMG/selectnewpest.nectarine.html

EARLY-SEASON MONITORING (6/10) Monitor the orchard early in the season as trees come into bloom to help detect potential pest problems early.

1. Monitor the orchard for plant bug and stink bug (view photos online).

2. Monitor trees for the presence of peach twig borers, fruittree leafrollers, or obliquebanded leafrollers, katydids, and western flower thrips (view photos online). Examine flowers and leaves on 2- to 3-year-old branches located at head height on each of 50 trees as you walk through each varietal block. • For peach twig borers and leafrollers, pull off a few flowers and examine for feeding, holes, or the

presence of caterpillars. • For katydids, spend about 30 seconds examining leaves for feeding damage. • For thrips, examine blossoms from each tree by slapping a shoot with five to ten blossoms against a

yellow card or look for the immature stages within the blossoms. Monitoring at this time will let you know the effectiveness of the dormant or bloom treatment and alert you to the need for additional treatment.

Pest What to look for Treatment threshold

Katydids Katydid feeding consists of small holes in the center of young leaves.

If any of the leaves examined show signs of feeding, treat.

Western flower thrips Thrips in the blossoms. If a single immature thrips is found, treat. . . . or . . . If two blossoms out of 50 sampled have adult thrips, treat.

Peach twig borer larvae At this time peach twig borers feed at the base of flowers where they bore into the calyx, creating small holes. They may also enter the tips of shoots causing them to wilt (see SHOOT STRIKE MONITORING).

If any are present, a treatment is necessary at first flight.

Fruittree leafroller, obliquebanded leafroller

Fruittree leafroller and obliquebanded leafrollers feed on blossoms as well as young foliage and begin to tie leaves together.

Thresholds have not been determined.


(6/10) Shoot Strike Monitoring 4 Online with photos at http://www.ipm.ucanr.edu/PMG/selectnewpest.nectarine.html

SHOOT STRIKE MONITORING (6/10) Shoot tips are killed when oriental fruit moth and peach twig borer larvae bore inside them and feed, resulting in “shoot strikes." Monitoring shoot strikes helps distinguish damage caused by these pests from counting similar-appearing damage and determine if the oriental fruit moth or peach twig borer populations require treatment. In orchards where mating disruption is used against oriental fruit moths, it gives an indication of whether it is working. THE COUNT METHOD—WHEN AND HOW TO SAMPLE

1. When to monitor depends on which species has been more prevalent in the past: a. Oriental fruit moth – monitor between 600-900 degree-days (DD) after the first trap catch for the 2nd

through 4th generations. b. Peach twig borer – monitor between 500-900 DD after the first trap catch during 1st through 3rd

generations. 2. Inspect a minimum of five trees per block (usually 5–10 acres of trees of the same variety). 3. Randomly select trees to inspect by starting with an outside tree and moving towards the middle of the

block to get a good cross-section of the block. 4. Pick a starting point and circle the tree looking up, down, and inside the tree, counting all shoot strikes. 5. Record the total number of shoot strikes on the form below before moving on to next tree. Do not distinguish

between old and new shoot strikes, but be careful not to confuse shoot damage from breakage or pests such the plant bug Calocoris, which will not leave a tunnel whereas oriental fruit moth and peach twig borer will.

6. Once five or more trees have been inspected, calculate the average strikes per tree using the form below. If you are approaching the treatment threshold (an average of three strikes per tree), sample a few more trees.

Grower, Orchard, Variety:_________________________________

Date Flight Tree 1 Tree 2 Tree 3 Tree 4 Tree 5 Total # Strikes

Average strikes/tree*

1st 2nd 3rd 4th

* Total number of strikes divided by number of trees inspected.

7. If larvae are present in the shoots, verify the predominant species causing the shoot strikes by examining several strikes. When oriental fruit moth (OFM) is present, fresh strikes may have excrement (frass) on the outside of the hole, whereas this is not the case with peach twig borer (PTB). Pull the shoot apart to find the larva. Use the description of the pests in the individual pest sections and the photos in the online version of this guideline to correctly identify the species. Generally, peach twig borer first appears before the leaves are 2 inches long. Oriental fruit moth strikes first appear when leaves are about 5 to 8 inches long. After the first generation, the flights tend to overlap and larvae of both species can be present. Knowing for sure which species is predominant is important in spray timing and in the selection of the most effective insecticide. It may be helpful to record your observations on a form like the one below for future reference.

Larval Identification Tree

Date

Flight

No. of OFM larvae

No. of PTB larvae

No. with no larvae

1st 2nd 3rd 4th


(6/10) Fruit Sampling 5 Online with photos at http://www.ipm.ucanr.edu/PMG/selectnewpest.nectarine.html

FRUIT SAMPLING (6/10) PREHARVEST FRUIT SAMPLES Preharvest fruit sampling will alert you to the need to treat before harvest. (Be sure to check the preharvest interval of the pesticide if treatment is necessary.) Monitor weekly beginning at color break (when nectarines start to turn reddish). How to Sample (View preharvest damage photos online for identification) Examine 100-200 randomly selected fresh fruit on the tree (10–20 fruit on 10 trees) by looking at it on the tree and rotating it slightly to detect damage caused by: • peach twig borer, oriental fruit moth, or larvae • live San Jose scale, or parasitized San Jose Scale • stink bugs and plant bugs • katydids • thrips • fruit rot • rust

FRUIT EVALUATION AT HARVEST Take a fruit damage sample at harvest to assess the effectiveness of the current year's IPM program and to determine the needs of next year's program; be sure to keep a record for each block. How to Sample (View harvest damage photos online for identification) Before the sorting process begins, examine 500 to 1,000 randomly selected fruit from harvest containers. Plan to sample 500 fruit for each variety unless unexpected damage is discovered, in which case increase the sample size up to a maximum of 1,000 fruit in order to thoroughly assess the damage. Distinguish damage caused by peach twig borer, oriental fruit moth, and leafrollers, San Jose scale, stink bugs, plant bugs, katydids, and thrips as well as brown rot, rust, and scab. Look for the presence of: • Larvae or larval feeding from peach twig borer, oriental fruit moth, or leafroller caterpillars

o Peach twig borer: shallow feeding holes. Over time these may appear as scabs. o Leafrollers: tunneling into fruit; shallow holes or grooves in the fruit surface; this can sometimes be difficult

to distinguish from severe thrips feeding that was done just after bloom. • Live or parasitized San Jose scale and halos or spots on the fruit surface. • Scabs, pits caused by stink bugs, plant bugs, and katydids. • Surface scarring caused by thrips feeding. • Fruit rot. In many cases, this damage may occur in conjunction with peach twig borer or oriental fruit moth

damage or other physical injury. • Scab lesions on fruit are dark spots and may have green or yellow halos. They are most commonly on the

upper surface and may merge to form large blotches. • Rust lesions, which can resemble stink bug damage but can be distinguished by the presence of spore masses

in the lesions, and lesions are often surrounded by halos. Record the number of fruit infested by larvae, type of larvae present or, if there are no larvae present, whether damage is surface feeding only or if the larvae penetrated the fruit. Record the number of fruit with live San Jose scale, or parasitized San Jose scale. Record the number of fruit with damage caused by stink bugs, plant bugs, katydids, thrips, and note any indication of rust, brown rot, and scab. Record results for harvest sample. (Example form available online)


(6/10) Relative Impact of the Timing of Pesticide Applications on Natural Enemies 6 Online with photos at http://www.ipm.ucanr.edu/PMG/selectnewpest.nectarine.html

RELATIVE IMPACT OF THE TIMING OF PESTICIDE APPLICATIONS ON NATURAL ENEMIES (6/10)

Timing Treatment

Caterpillar parasites (Copidosoma sp., Macrocentrus sp.) Lacewings

Lady beetles (Chilocorus spp.)

Minute pirate bugs

Predatory mites (Galendromus sp., Typhlodromus sp.)

Scale parasites (Aphytis sp.) Spiders

DORMANT oil L L L L L L L oil + IGR1 L L L L L L L oil + OP2 L M L M L L M oil + pyrethroid3 L L L M H — L oil + spinosyns4 L L L L L L/M L BLOOM Bt5 L L L L L L L diamides6 L L L L L L — Dimilin L L L L L L L Intrepid L L L L L L L spinosyns4 M L M L L H L IN SEASON Avaunt L L L L — — — carbamate7 H H H H H H H diamides6 L L L L L — — Movento L L L L L L L OP2 H M H H M H H pyrethroid3 H L/M H H H H H spinosyns4 M/H L/M H M L H —

H = high M = moderate L = low — = no information 1 IGR = insect growth regulators (diflubenzuron-Dimilin, buprofezin-Centaur, pyriproxyfen-Seize) 2 OP = organophosphate (Diazinon, Imidan) 3 pyrethroid (Asana, Ambush, Pounce) 4 Spinosyns = spinosad (Success, Entrust), spinetoram (Delegate) 5 Bt = Bacillus thuringiensis 6 Diamides = chlorantraniliprole (Altacor) 7 carbamate (Carzol, Lannate, Sevin)

Acknowledgments: C. Pickel, UC IPM Program, Sutter/Yuba counties; W. J. Bentley, UC IPM Program, Kearney Agricultural Center, Parlier; J. K. Hasey, UCCE Sutter/Yuba counties; K. R. Day, UCCE Tulare Co.


(8/15) Relative Toxicities of Insecticides And Miticides Used in Nectarines to Natural Enemies and Honey Bees 7 Online with photos at http://www.ipm.ucanr.edu/PMG/selectnewpest.nectarine.html

RELATIVE TOXICITIES OF INSECTICIDES and MITICIDES USED IN NECTARINES TO NATURAL ENEMIES and HONEY BEES (8/15)

Common name (Example trade name)

Mode of Action1

Selectivity (affected groups)2

Predatory Mites3

General Predators4 Parasites4

Honey bees5

Duration of impact to natural enemies6

abamectin (Agri-Mek) 6 moderate (mites) M L M/H I acetamiprid (Assail) 4A moderate (sucking

insects, larvae) —7 — — II moderate

azadirachtin (Neemix) un broad (insects, mites) M L/M L/M II short Bacillus thuringiensis ssp. kurstaki 11A narrow (caterpillars) L L L III none beta-cyfluthrin + imidacloprid (Leverage)

3A + 4A — — — — I —

bifenazate (Acramite) un narrow (spider mites) L L L II short buprofezin (Centaur) 16 narrow (scales) L H8 L II long carbaryl (Sevin XLR Plus) 1A broad (insects, mites) M H M I long chlorantraniliprole (Altacor) 28 narrow (primarily

caterpillars) L L L/M III short

clofentezine (Apollo) 10A narrow (mites) L L L III short diazinon–foliar 1B broad (insects, mites) L H H I moderate to

long diflubenzuron (Dimilin) 15 — L H L II — esfenvalerate (Asana) 3A broad (insect, mites) H M H I moderate fenbutatin oxide (Vendex) 12B narrow (pest mites) L L L III short hexythiazox (Onager, Savey) 10A narrow (mites) L L L II short imidacloprid (Admire) 4A narrow (sucking insects) M M H I short to

moderate indoxacarb (Avaunt) 22A narrow (caterpillars,

plant bugs) L L L I moderate

methomyl (Lannate) 1A broad (insects, mites) H H H I moderate methoxyfenozide (Intrepid) 18 narrow (caterpillars) L L L II none neem oil (Trilogy) un broad (soft-bodied

insects) L L L II short

permethrin (Pounce) 3A broad (insects, mites) H H H I long petroleum oil un broad (exposed insects,

mites) L L L II short

phosmet (Imidan) 1B broad (insects, mites) H H H I moderate to long

pyridaben (Nexter) 21A broad (insects, mites) H M — I short pyriproxyfen (Seize) 7C narrow (scale, beetles) L H8 L II long spinetoram (Delegate) 5 narrow (caterpillars,

thrips, whiteflies, aphids, scales)

M M10 L/M II moderate11

spinosad (Entrust, Success) 5 narrow (caterpillars, thrips, whiteflies, aphids, scales)

M M10 L/M II short to moderate

spirodiclofen (Envidor) 23 narrow (mites) L — — II — sulfur un narrow (mites) L/H L H III short H = high M = moderate L = low — = no information un = unknown or uncertain mode of action

Relative Toxicities of Insecticides and Miticides Used in Nectarines (continued) 1 Rotate chemicals with a different mode-of-action Group number, and do not use products with the same mode-of-action Group number more than twice

per season to help prevent development of resistance. For example, the organophosphates have a Group number of 1B; chemicals with a 1B Group


(8/15) Relative Toxicities of Insecticides And Miticides Used in Nectarines to Natural Enemies and Honey Bees 8 Online with photos at http://www.ipm.ucanr.edu/PMG/selectnewpest.nectarine.html

number should be alternated with chemicals that have a Group number other than 1B. Mode of action Group numbers (“un" = unknown or uncertain mode of action) are assigned by IRAC (Insecticide Resistance Action Committee). For additional information, see their Web site at http://www.irac-online.org/.

2 Selectivity: broad means it affects most groups of insects and mites; narrow means it affects only a few specific groups. 3 Generally, toxicities are to the native strain of the western predatory mite, Galendromus occidentalis. Where differences have been measured in toxicity of

the pesticide-resistant strain versus the native strain, these are listed as pesticide-resistant strain/native strain. 4 Toxicities are averages of reported effects and should be used only as a general guide. Actual toxicity of a specific chemical depends on the species of

predator or parasite, environmental conditions, and application rate. 5 Ratings are as follows: I—Do not apply or allow to drift to plants that are flowering; II—Do not apply or allow to drift to plants that are flowering, except

when the application is made between sunset and midnight if allowed by the pesticide label and regulations; III—No bee precaution, except when required by the pesticide label or regulations. For more information about pesticide synergistic effects, see Bee Precaution Pesticide Ratings (available online at http://ipm.ucanr.edu/beeprecaution/).

6 Duration: short means hours to days; moderate means days to 2 weeks; and long means many weeks or months. 7 May cause flare-ups of spider mite populations. 8 Kills lady beetles. 9 If rate is 0.02 lb a.i./acre, rating is II.

10 Toxic against some natural enemies (predatory thrips, syrphid fly and lacewing larvae, beetles) when sprayed and up to 5-7 days after, especially for syrphid fly larvae.

11 Residual is moderate if solution is between pH of 7 to 8. Acknowledgments: This table was compiled based on research data and experience of University of California scientists who work on a variety of crops and contribute to the Pest Management Guideline database, and from Flint, M. L. and S. H. Dreistadt. 1998. Natural Enemies Handbook: An Illustrated Guide to Biological Pest Control, ANR Publication 3386.


(8/15) General Properties of Fungicides Used in Nectarines 9 Online with photos at http://www.ipm.ucanr.edu/PMG/selectnewpest.nectarine.html

GENERAL PROPERTIES OF FUNGICIDES USED IN NECTARINES (8/15)


Chemical class Activity Mode of action (Group #)1

Resistance potential

Comments

azoxystrobin (Abound) Qol2 contact, systemic single-site (11) high bordeaux inorganic contact multi-site (M1) low captan phthalamide contact multi-site (M4) low highly toxic to honey bee

larvae chlorothalonil (Bravo, Echo) chloronitrile contact multi-site (M5) low copper inorganic contact multi-site (M1) low cyprodinil (Vangard) anilinopyrimidine mostly contact single-site (9) high dicloran (Botran) aromatic hydrocarbon contact, systemic

(local) single-site (14) medium

fenbuconazole (Indar) DMI3 -triazole systemic (local) single-site (3) high fenhexamid (Elevate) hydroxyanilide contact single-site (17) high fosetyl-al (Aliette) ethyl phosphonates systemic unknown (33) low iprodione (Rovral) dicarboximide systemic (local) single-site?(2) medium toxic to honey bee larvae mefenoxam (Ridomil Gold) acylalanine contact, systemic single-site (4) high metconazole (Quash) DMI3 -triazole systemic (local) single-site (3) high myclobutanil (Rally) DMI3 -triazole systemic (local) single-site (3) high propiconazole (Bumper/Tilt) DMI3 -triazole systemic (local) single-site (3) high pyraclostrobin/boscalid (Pristine)

Qol2/SDHI5 contact, systemic single-site/single-site (11/7)

high

pyrimethanil (Scala) anilinopyrimidine mostly contact single-site (9) high quinoxyfen (Quintec) quinoline contact single-site (13) medium sulfur inorganic contact multi-site (M2) low highly toxic to native strains of

western predatory mite (Galendro–mus occidentalis) and to parasites

tebuconazole (Elite) DMI3 -triazole systemic (local) single-site (3) high tebuconazole/trifloxystrobin (Adament)

DMI3 -triazole/Qol2 systemic single-site/ single-site (3/11)

medium

thiophanate-methyl (Topsin) MBC6 systemic (local) single-site (1) very high trifloxystrobin (Gem) Qol2 contact, systemic7 single-site (11) high8 ziram carbamate (DMDC4 ) contact multi-site (M3) low 1 Group numbers are assigned by the Fungicide Resistance Action Committee (FRAC) according to different modes of actions (for more information, see

http://www.frac.info/). Fungicides with a different group number are suitable to alternate in a resistance management program. In California, make no more than one application of fungicides with mode of action Group numbers 1, 4, 9, 11, or 17 before rotating to a fungicide with a different mode of action Group number; for fungicides with other Group numbers, make no more than two consecutive applications before rotating to fungicide with a different mode of action Group number.

2 Qol = quinone outside inhibitor (strobilurin) 3 DMI = demethylation (sterol) inhibitor 4 DMDC = dimethyl dithiocarbamate 5 SDHI = Succinate dehydrogenase inhibitor 6 MBC = Methyl benzimidazole carbamate 7 Fungicide is generally considered to have systemic action based on performance data, but this characteristic has not been necessarily proven experimentally

using more rigorous assays (e.g. radioactively labeled compounds). 8 Resistance has been found in California for certain fungicides with a single-site mode of action. To reduce the risk of resistance development, take the mode

of action into account when choosing a fungicide. At the beginning of a treatment program, use a fungicide with a multi-site mode of action; for subsequent applications rotate or mix fungicides with different mode of action FRAC numbers. Use labeled rates (preferably the upper range) of the single-site fungicides, and limit the total number of applications per season.

Acknowledgment: Adaskaveg et al., 2017 Efficacy and Timing of Fungicides, Bactericides, and Biologicals for Deciduous Tree Fruit, Nut, Strawberry, and Vine Crops.


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FUNGICIDE EFFICACY (6/17)

Resistance Brown rot 2 Powdery Leaf Shot Fungicide*** Risk (FRAC#)1 Blossom Fruit mildew2 Scab Rust curl hole Bumper,Tilt high (3) ++++ ++++ +++ ++ +++ ---- +/- Elite,Orius,Tebuzol**,Tebuconazole

high (3) ++++ ++++ +++ ++ +++ ---- +

Fontelis high (7)4 ++++ +++ ++++ +++ ND ---- +++10,12 Indar high (3) ++++ ++++ +++ ++ ND ---- +/- Inspire Super high (3/9) ++++ ++++ +++ ++ ND ---- +/- Luna Experience medium (3/7) ++++ ++++ +++ ---- +++ ---- +/- Luna Sensation medium (7/11)4 ++++ ++++ +++ +++ +++ ND ++++10,12 Merivon medium (7/11)4 ++++ ++++ +++ +++ +++ ND ++++10,12 Pristine medium (7/11)4 ++++ ++++ +++ +++ ND ND ++++10,12 Quadris Top medium (3/11) ++++ ++++ +++ ---- +++ ---- +/- Quash high (3) ++++ ++++ +++ ND +++ ---- +++10,12 Quilt Xcel,Avaris 2XS medium (3/11) ++++ ++++ +++ ---- +++ ---- +/- Rovral5+ oil6 low (2) ++++ NL + + ++ ---- ++ Scala7 high (9)3,4 ++++ +++7 ND ND ND ---- + Topsin-M,T-Methyl, Incognito,Cercobin

high (1) 3,4 ++++ ++++ +++ +++ + ---- ----

Vangard7 high (9) 3,4 ++++ +++7 ND ND ND ---- + Elevate high (17)4 +++ +++ ND ND ND ND ND Rally high (3) +++ +++ ++++ ---- ---- ---- ---- Rhyme high (3) +++ ++ +++ ND ND ---- +10 Rovral,Iprodione, Nevado5

low (2) +++ NL ---- ---- ---- ---- ----

Abound high (11)4 ++ + ++ ++++ +++ ---- ++ Botran medium (14) ++ + ND ND ND ND ND Bravo,Echo,Equus8,9 low (M5) ++ ---- ---- +++ + +++ +++ Captan9 low (M4) ++ ++ ---- +++ ---- ---- +++10,12 Gem high (11)4 ++ + ++ ++++ +++ ---- ++ Ph-D, Oso high (19) ++ ++ ++ ND ND ND ND Syllit medium (U12) + ---- ----- +++ ---- ++ +++ Copper low (M1) +/- ---- ---- ---- ---- +++ +++ Sulfur9 low (M2) +/- +/- +++ +++ +++ ---- ---- Thiram11 low (M3) +/- ---- ---- +++ ---- ++++ +++ Ziram low (M3) +/- ---- ---- +++ ---- ++++ +++ Quintec high (13) ---- ---- ++++ ---- ---- ---- ---- Vivando high (U8) ---- ---- +++ ---- ---- ---- ----

++++ = excellent and consistent, ++ = moderate and variable +/- = minimal and often ineffective ND = no data +++ = good and reliable + = limited and/or erratic ---- = ineffective NL = not on label * Registration pending in California. ** Not registered, label withdrawn or inactive *** - Postharvest fruit registrations in California include: Penbotec, Scholar, and Mentor (Section 18). 1 Group numbers are assigned by the Fungicide Resistance Action Committee (FRAC) according to different modes of actions (for more information, see

http://www.frac.info/). Fungicides with a different group number are suitable to alternate in a resistance management program. In California, make no more than one application of fungicides with mode-of-action Group numbers 1, 4, 9, 11, or 17 before rotating to a fungicide with a different mode-of-action Group number; for fungicides with other Group numbers, make no more than two consecutive applications before rotating to fungicide with a different mode-of-action Group number.

2 Do not use fungicides with the same FRAC number and high resistance risk more than twice in one year. 3 Strains of Monilinia fructicola resistant to Topsin-M and T-Methyl are present in some peach and nectarine orchards. Resistant strains of the jacket rot fungus,

Botrytis cinerea, and powdery mildew fungi have been reported in California on crops other than almond and stone fruits and may have the potential to develop in peach and nectarine with overuse of fungicides with similar chemistry. Sub-populations of both Monilinia spp. have been shown to be resistant to AP (FRAC 9) fungicides on prune in CA.

4 To reduce the risk of resistance development, start treatments with a fungicide with a multi-site mode of action; rotate or mix fungicides with different mode of action FRAC numbers for subsequent applications, use labeled rates (preferably the upper range), and limit the total number of applications/season.

5 Blossom blight only; not registered for use after petal fall. 6 Oil is a "light" summer oil, 1-2% volume/volume.


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7 High summer temperatures and relative humidity reduce efficacy. 8 Do not use after jacket (shuck) split. 9 Do not use in combination with or shortly before or after oil treatment. 10 Not effective if used as a dormant treatment. 11 For use on peach only; not registered on nectarine. 12 For shot hole management, dormant treatments with copper, ziram, and dodine are highly effective. Petal fall treatments should be used to complement the

management program.

Acknowledgment: Adaskaveg et al., 2017. Efficacy and Timing of Fungicides, Bactericides, and Biologicals for Deciduous Tree Fruit, Nut, Strawberry, and Vine Crops(PDF).

MOST EFFECTIVE TREATMENT TIMING FOR KEY DISEASES (6/17)

Not all indicated timings may be necessary for disease control.

Bloom 3-6 Weeks Preharvest1 Disease Dormant 20-40% 80-100% Postbloom 3 weeks 1 week Brown rot — ++ +++ + ++ +++ Powdery mildew —/ND ++ +++ +++2 — — Leaf curl3 +++ + — — — — Rust +4 — — +++ ++ — Scab — + ++ +++ — — Shot hole5 +++ + + ++ — — Rating: +++ = most effective, ++ = moderately effective, + = least effective, — = ineffective, ND= no data but needs to be evaluated. 1 Timing not exact; weather conditions determine need for treatment. 2 Apply until pit hardening 3 Treatment should be made before bud break and preferably before bud swell. 4 Dormant treatment with liquid lime sulfur. 5 Fall application before winter rains begin is the most important; additional spring sprays are seldom required but may be needed to

protect the fruit if heavy, persistent spring rains occur. Acknowledgment: Adaskaveg et al., 2017. Efficacy and Timing of Fungicides, Bactericides, and Biologicals for Deciduous Tree Fruit, Nut, Strawberry, and Vine Crops(PDF).


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FUNGICIDE RESISTANCE MANAGEMENT (6/17) Note: Not all indicated timings may be necessary for disease control. If treatments are needed based on weather monitoring or environmental monitoring models, suggested fungicide groups are listed for each timing. HOW TO USE THIS TABLE

1. Identify the disease(s) that need(s) to be managed. Know the disease history of the orchard especially from the previous season.

2. Select one of the suggested FRAC1 mode-of-action Group numbers. Numbers separated by slashes are premixtures, whereas numbers grouped by pluses are tank mixtures. If several diseases need to be managed, select a group that is effective against all diseases. Refer to GENERAL PROPERTIES OF FUNGICIDES table for fungicides belonging to each FRAC1 group. Group numbers are listed in numerical order within the suggested disease management program.

3. Rotate groups for each application within a season and, if possible, use each group only once per season, except for multi-site mode-of-action materials or natural products/biological controls (e.g., M2, NP/BC).

FRAC1 Group Numbers Suggested for Disease Management Program

Bloom 3-6 Weeks Preharvest Disease Dormant 20-40% 80-100% Postbloom 3 weeks 1 week

Brown rot ---- 13 2+oil 3, 3/7 3/11 9 9/11, 17, 19

13 2+oil 34, 3/7 3/11 7/11 9 9/11 17, 19

3 3/11 7/11 9/11 17

3 3/7, 3/11 7/11 9/11 17, 19

34 3/7, 3/11 7/11 9/11 17, 19

Powdery mildew

----/M22 13 2+oil 3, 3/7, 3/11

13 3, 3/7, 3/11 7/11

3, 7 3/7, 7/11 11, 19 M22 NP/BC5

---- ----

Leaf curl M1, M3 M5, M7

M3 M5, U12

---- ---- ---- ----

Rust M22 ---- ---- 13 3 7/11 11 M22

3 7/11 11 M22

----

Scab ---- 13 3 3/11 7/11 9/11 M3 M4 M7

13 3 3/11 7/11 9/11 M4 M5 M7

13 3 3/11 7/11 9/11 11 M22 M4, M7

---- ----

Shot hole M1 M3 M5 M7

2 M3 M4 M5 M7

2 7/11 M3 M4 M5

7/11 11 M4

---- ----

1 Group numbers are assigned by the Fungicide Resistance Action Committee (FRAC) according to different modes of actions (for more information, see http://www.frac.info/). Group numbers are listed in numerical order within the suggested disease management program. Fungicides with a different group number are suitable to alternate in a resistance management program. Refer to the fungicide efficacy table for fungicides belonging to each FRAC group.


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2 Efficacy of liquid lime sulfur in dormant applications has not been determined for powdery mildew. Use liquid lime sulfur in dormant applications and wettable sulfur at and after pre-bloom.

3 Strains of Monilinia fructicola resistant to Benlate (label withdrawn), Topsin-M, and T-Methyl are present in some California peach/nectarine orchards. Resistant strains of the jacket rot fungus, Botrytis cinerea, and powdery mildew fungi have been reported in California on crops other than almond and stone fruits and may have the potential to develop in peach/nectarine with overuse of fungicides with similar chemistry. Subpopulations of both Monilinia spp. have been shown to be resistant to AP (FRAC 9) fungicides on prune in CA.

4 Among the group 3 fungicides, only Elite/Tebuzol/Orius and Quash have some activity against Botrytis cinerea. 5 NP/BC = Natural Products/Biological Controls such as copper, sulfur, potassium bicarbonate (Kaligreen), Streptomyces lydicus (Actinovate AG), Bacillus

pumilus (Sonata), and Bacillus subtilis (Serenade) Acknowledgment: Adaskaveg et al., 2017. Efficacy and Timing of Fungicides, Bactericides, and Biologicals for Deciduous Tree Fruit, Nut, Strawberry, and Vine Crops(PDF.


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Insects and Mites (Section reviewed 6/10)

BLACK PEACH APHID (8/15) Scientific Name: Brachycaudus persicae DESCRIPTION OF THE PEST In California, this aphid is prevalent in the San Joaquin Valley. Winged and wingless adults of the black peach aphid are shiny black and about 0.1 inch long. The nymphs are reddish brown. Wingless forms overwinter on the roots of nectarine and other closely related trees. In early spring, some migrate from roots to new growth and start colonies on the young leaves. Several generations of female aphids are produced. In early summer, winged adults are produced and migration to other trees occurs. Aboveground colonies usually disappear by midsummer as wingless forms migrate to the roots to feed and overwinter. DAMAGE Injury consists of leaf curling, yellowing, and premature drop; the leaf curling is first evident at shoot terminals. If aphids are abundant, honeydew excretion may cause black sooty mold to appear on leaves and fruit. Ants may also become a problem, because they tend the aphids while they are on the roots. MANAGEMENT In spring when growth begins, look for colonies of this aphid when monitoring other pests. The multicolored Asian lady beetle, Harmonia axyridis, is a common predator of these aphids. This aphid is not particularly damaging, and populations may be managed by predators. If this aphid has presented problems in the past, take control measures in spring.


Amount per acre**

REI‡ (hours)

PHI‡ (days)

UPDATED 8/15 The following are ranked with the pesticides having the greatest IPM value listed first—the most effective and least harmful to natural enemies and honey bees, and the environment are at the top of the table. When choosing a pesticide, consider information relating to air and water quality, resistance management, and the pesticide's properties and application timing. Not all registered pesticides are listed. Always read the label of the product being used. A. IMIDACLOPRID (Admire Pro) 1.4–2.8 fl oz 12 0 MODE-OF-ACTION GROUP NUMBER1: 4A COMMENTS: Apply as foliar spray after pollination is complete and bees are no longer present in the orchard.

Thorough, uniform coverage is essential. B. ACETAMIPRID (Assail 70WP) 1.1–2.3 oz 12 7 MODE-OF-ACTION GROUP NUMBER1: 4A COMMENTS: Toxic to bees; do not spray directly or allow to drift onto blooming crops or weeds where bees are foraging.

** For dilute applications, rate is per 100 gal water to be applied in 300-500 gal water/acre, according to label; for concentrate applications, use 80-100 gal water/acre, or lower if the label allows.

‡ Restricted entry interval (REI) is the number of hours (unless otherwise noted) from treatment until the treated area can be safely entered without protective clothing. Preharvest interval (PHI) is the number of days from treatment to harvest. In some cases the REI exceeds the PHI The longer of two intervals is the minimum time that must elapse before harvest.

1 Rotate chemicals with a different mode-of-action Group number, and do not use products with the same mode-of-action Group number more than twice per season to help prevent the development of resistance. For example, the organophosphates have a Group number of 1B; chemicals with a 1B Group number should be alternated with chemicals that have a Group number other than 1B. Mode of action Group numbers are assigned by IRAC (Insecticide Resistance Action Committee). For additional information, see their Web site at http://www.irac-online.org/.


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BROWN MITE (8/15) Scientific Name: Bryobia rubrioculus DESCRIPTION OF THE PEST Brown mites can be recognized by their flattened bodies and long front legs. Adults are brownish green; nymphs are red at first. Brown mites overwinter as eggs on spurs and branches. Eggs are red and similar in appearance to European red mite eggs but lack a stipe. Eggs hatch in spring and the young move out to leaves where they feed but do not produce webbing. Brown mites feed only during the cool parts of the day and migrate off the leaves during midday. DAMAGE Brown mites feed by sucking the contents out of leaf cells. Such leaf damage reduces tree vitality and can adversely affect fruit size. Leaf injury caused by brown mites begins as a mottling and browning of leaves. Trees can tolerate low to moderate populations of brown mite, but heavy populations can remove almost all the chlorophyll from leaves and entire trees will take on a pale yellow appearance. MANAGEMENT Maintain mite predators in order to keep brown mite populations at low levels. Biological Control Several predaceous species feed on brown mite, including lacewings (Chrysoperla spp., Chrysopa spp., and Hemerobius sp), damsel bugs (Nabis sp.), lady beetles (Hippodamia convergens and Stethorus picipes), and minute pirate bug (Orius tristicolor). Organically Acceptable Methods Certain oil sprays and naturally occurring predators serve as organically acceptable management tools. Monitoring and Treatment Decisions Monitor for brown mite eggs along with other pests when taking the DORMANT SHOOT SAMPLE. Use dormant sprays with oils at the high rate to help control the overwintering eggs if 20% or more of the shoots have eggs. An insecticide can be added to control other pests. Miticides may be necessary in some orchards in spring or summer but only when mite populations begin damaging foliage. During the hot part of the day, brown mites will not be found on leaves, but they can be monitored using beating trays. Allowing low populations of brown mites in the orchard during spring enables mite predators to increase their population to levels that are more effective in controlling webspinning mites. Generally, hot weather and predators cause brown mite populations to decline in summer.


Amount to use** REI‡ (hours)

PHI‡ (days) (conc.) (dilute)

UPDATED 8/15 The following are ranked with the pesticides having the greatest IPM value listed first—the most effective and least harmful to natural enemies and honey bees, and the environment are at the top of the table. When choosing a pesticide, consider information relating to air and water quality, resistance management, and the pesticide's properties and application timing. Not all registered pesticides are listed. Always read the label of the product being used.

DORMANT OR DELAYED-DORMANT (PREFERRED TIMING) A. DORMANT OIL such as: DORMANT FLOWABLE EMULSION 6 gal 1.5 gal 12 0 NARROW RANGE OIL (440 or higher)# 6 gal 1.5 gal 12 0 MODE OF ACTION: Contact including smothering and barrier effects. COMMENTS: Choose a narrow range oil with a 50% distillation point of 440 or higher for dormant season use.

Always check with your certifier as to which oils are organically acceptable. With good coverage, oil will control European red mite and brown mite eggs and low infestations of San Jose scale. Use in conjunction with a bloom time spray of Bt to control peach twig borer.


(8/15) Brown Mite 16 Online with photos at http://www.ipm.ucanr.edu/PMG/selectnewpest.nectarine.html




UPDATED 8/15

SPRING AND SUMMER A. BIFENAZATE (Acramite 50WS) 0.75–1 lb/acre 12 3 MODE-OF-ACTION GROUP NUMBER1: un COMMENTS: Relatively safe for beneficial predaceous mites. Apply with ground equipment. Requires complete

coverage of both leaf surfaces for effective control. Toxic to bees; do not spray directly or allow to drift onto blooming crops or weeds where bees are foraging.

B. SPIRODICLOFEN (Envidor 2SC) 16–18 fl oz/acre 12 7 MODE-OF-ACTION GROUP NUMBER1: 23 COMMENTS: Apply with ground equipment. Requires complete coverage of both leaf surfaces for effective control. C. FENBUTATIN OXIDE* (Vendex 50WP) 1–2 lb/acre 48 14 MODE-OF-ACTION GROUP NUMBER1: 12B COMMENTS: Can be combined with oil. D. NARROW RANGE OIL# 2% 4% 12 0 MODE OF ACTION: Contact including smothering and barrier effects. COMMENTS: Oil used alone will only provide partial control. Always apply oils to well-watered trees and never

when trees are stressed by hot (above 90°F), windy, dry (relative humidity lower than 20%) conditions or when such conditions are likely to occur within a few days after application. Additional applications may be needed at 2-week intervals, which may increase the potential for phytotoxicity. Do not apply oil within 2 weeks of captan or sulfur.

E. CLOFENTEZINE (Apollo) 2–8 oz/acre 12 10 MODE-OF-ACTION GROUP NUMBER1: 10A COMMENTS: Kills eggs and young larval stages so it is best suited for an early season application if needed. Use

rates below 4 oz/acre only when adequate numbers of predators are present. Good coverage is a must; use a minimum of 50 gal water/acre for concentrate sprays and a maximum of 400 gal water/acre for dilute. To delay development of resistance, use only once per season.

F. HEXYTHIAZOX (Onager) 12–24 oz 3–6 oz 12 7 (Savey 50DF) 3–6 oz 0.75–1.5 oz 12 28 MODE-OF-ACTION GROUP NUMBER1: 10A COMMENTS: Apply after bloom but before adult mite buildup. Controls eggs and immatures that are sprayed or

move onto treated surfaces; does not kill adult mites but will kill eggs laid on treated surfaces. Do not make more than 1 application per year.


* Permit required from county agricultural commissioner for purchase or use. ‡ Restricted entry interval (REI) is the number of hours (unless otherwise noted) from treatment until the treated area can be

safely entered without protective clothing. Preharvest interval (PHI) is the number of days from treatment to harvest. In some cases the REI exceeds the PHI The longer of two intervals is the minimum time that must elapse before harvest.

# Acceptable for use on organically grown produce. 1 Rotate chemicals with a different mode-of-action Group number, and do not use products with the same mode-of-action

Group number more than twice per season to help prevent the development of resistance. For example, the organophosphates have a Group number of 1B; chemicals with a 1B Group number should be alternated with chemicals that have a Group number other than 1B. Mode of action Group numbers (“un" =unknown or uncertain mode of action) are assigned by IRAC (Insecticide Resistance Action Committee). For additional information, see their Web site at http://www.irac-online.org/.


(8/15) European Fruit Lecanium 17 Online with photos at http://www.ipm.ucanr.edu/PMG/selectnewpest.nectarine.html

EUROPEAN FRUIT LECANIUM (8/15) Scientific Name: Parthenolecanium corni DESCRIPTION OF THE PEST European fruit lecanium, also known as the brown apricot scale, occurs throughout the Central Valley, but is rarely a problem. The adult female's domed shell is shiny brown, about 0.4 inches in diameter. Eggs are laid in spring and hatch from May to July. The young develop through the remainder of the season and overwinter on twigs and small branches as partly grown crawlers. There is one generation each year. DAMAGE The chief injury is the production of honeydew that, in large amounts, can damage leaves and fruit. Sooty mold growing in the honeydew can cause blackened areas on leaves and fruit. MANAGEMENT Biological control is frequently effective; if treatment is needed, oil applied during dormancy or delayed dormancy is an effective way to reduce populations of this pest and the least disruptive of natural enemies. Increased populations of this scale may appear when dormant sprays are omitted. Biological Control Fruit lecanium is frequently kept under control by parasites including Aphytis spp., Coccophagus spp., Encarsia spp., and Metaphycus spp. and predators including lady beetles and lacewings. If present, ants will interfere with biological control; note their presence when monitoring. Organically Acceptable Methods Biological control and certain oil sprays are organically acceptable methods. Monitoring and Treatment Decisions To determine if a dormant or delayed-dormant treatment is warranted, follow sampling and treatment threshold guidelines in DORMANT SHOOT SAMPLING. Look for parasitized scale during the summer by lifting up scale covers as well as examining the covers for exit holes. If a large number of scales are parasitized, treatment may not be needed during the following dormant season.




UPDATED 8/15 The following are ranked with the pesticides having the greatest IPM value listed first—the most effective and least harmful to natural enemies and honey bees, and the environment are at the top of the table. When choosing a pesticide, consider information relating to air and water quality, resistance management, and the pesticide's properties and application timing. Not all registered pesticides are listed. Always read the label of the product being used. A. DORMANT OIL such as: DORMANT FLOWABLE EMULSION 6 gal 1–1.5 gal 12 0 NARROW RANGE OIL (440 or higher)# 4 gal 1.5 gal 12 0 MODE OF ACTION: Contact including smothering and barrier effects. COMMENTS: Choose a narrow range oil with a 50% distillation point of 440 or higher for dormant season use.

Always check with your certifier as to which oils are organically acceptable. Oil alone can control moderate populations of soft scales.


# Acceptable for use on organically grown produce. ‡ Restricted entry interval (REI) is the number of hours (unless otherwise noted) from treatment until the treated area can be



(8/15) European Red Mite 18 Online with photos at http://www.ipm.ucanr.edu/PMG/selectnewpest.nectarine.html

EUROPEAN RED MITE (8/15) Scientific Name: Panonychus ulmi DESCRIPTION OF THE PEST The female European red mite is about 0.02 inch long and has a brick red, globular body with long curved hairs that arise from white spots or tubercles on the back. Nymphs or unfed females may appear greenish. European red mite eggs are red, slightly flattened, and have a stipe protruding from the top. They overwinter in the egg stage on twigs and spurs. Eggs hatch in early spring just after the trees leaf out, and many generations (8–10) are produced before fall. Ordinarily European red mite populations build up slowly during spring and do not become apparent until large populations are present. DAMAGE European red mites remove the contents of the leaf cells as they feed, causing leaves to take on a finely mottled appearance. Rarely do European red mites cause leaf drop in nectarine trees. MANAGEMENT European red mites provide an early season food source for predatory mites and do little damage unless the orchard is heavily infested. Allowing low populations of European red mites in spring helps build predator mite populations to build, which can later help control the more damaging webspinning mites. Generally treatments for this mite are applied in the dormant to delayed-dormant season. Biological Control The same predators that feed on Pacific and twospotted mites will also feed on European red mites. While the western predatory mite can sustain itself on European red mites, it cannot break the shell of European red mite eggs. Thus it takes longer for this predator to bring a population of these mites under control. Cultural Control Culturally, little can be done to control European red mite, as it is generally more abundant in well-managed, vigorous orchards. Organically Acceptable Methods Biological control and sprays of certain narrow range oil are organically acceptable management tools. Monitoring and Treatment Decisions Monitor for European red mite eggs along with other pests when taking the DORMANT SHOOT SAMPLE. Examine leaf scars and growth rings on twigs for the presence of eggs. Use an oil spray during dormancy to help control the overwintering eggs if 20% or more of the shoots have eggs, but remember that low to moderate populations are beneficial because they provide food for predators. During summer, look for stippling or bronzing on leaves. No specific numbers have been developed to initiate treatment for European red mites.


Amount per acre** REI‡ (hours)



DORMANT AND DELAYED-DORMANT A. NARROW RANGE OIL# (440 or higher) 4–6 gal 1–1.5 gal 12 0 MODE OF ACTION: Contact including smothering and barrier effects. COMMENTS: Choose a narrow range oil with a 50% distillation point of 440 or higher for dormant season use.

Always check with your certifier as to which oils are organically acceptable. With good coverage, oil will control European red mite and brown mite eggs and low infestations of San Jose scale. Use in conjunction with a bloom time spray to control peach twig borer.


(8/15) European Red Mite 19 Online with photos at http://www.ipm.ucanr.edu/PMG/selectnewpest.nectarine.html




UPDATED 8/15

POSTBLOOM A. BIFENAZATE (Acramite 50WS) 0.75–1 lb/acre 12 3 MODE-OF-ACTION GROUP NUMBER1: un COMMENTS: Relatively safe for beneficial predaceous mites. Apply with ground equipment. Requires complete


B. SPIRODICLOFEN (Envidor 2SC) 16–18 fl oz/acre 12 7 MODE-OF-ACTION GROUP NUMBER1: 23 COMMENTS: Apply with ground equipment; need complete coverage of both leaf surfaces for good control. C. ABAMECTIN* (Agri-Mek SC) 2.25–4.25 fl oz 0.5–1 fl oz 12 21 MODE-OF-ACTION GROUP NUMBER1: 6 COMMENTS: May be combined with oil. Do not make more than 2 applications per growing season and allow at

least 21 days between treatments. Highly toxic to bees; do not spray directly or allow to drift onto blooming crops or weeds where bees are foraging. To avoid illegal residues, see label for required spray additives.

D. FENBUTATIN OXIDE* (Vendex 50WP) 1–2 lb/acre 48 14 MODE-OF-ACTION GROUP NUMBER1: 12B COMMENTS: Can be combined with oil. E. NARROW RANGE OIL# (Superior, Supreme) 4 gal 1–1.5 gal See label 0 MODE OF ACTION: Contact including smothering and barrier effects. COMMENTS: Do not apply during the same season as propargite. Will reduce mite populations by 50%. Multiple

applications may be necessary to keep populations below economic levels. F. CLOFENTEZINE (Apollo) 2–8 oz/acre 12 10 MODE-OF-ACTION GROUP NUMBER1: 10A COMMENTS: Kills eggs and young larval stages so it is best suited for an early season application if needed. Use

rates below 4 oz/acre only when adequate numbers of predators are present. Good coverage is a must; use a minimum of 50 gal water/acre for concentrate sprays and a maximum of 400 gal water/acre for dilute. To delay development of resistance, use only once per season.

G. HEXYTHIAZOX (Onager) 12–24 oz 3–6 oz 12 7 (Savey 50DF) 3–6 oz 0.75–1.5 oz 12 28 MODE-OF-ACTION GROUP NUMBER1: 10A COMMENTS: Apply after bloom but before adult mite buildup. Controls eggs and immatures that are sprayed or


** For dilute applications, rate is per 100 gal water to be applied in 300-500 gal water/acre, according to label; for concentrate applications, use 80-100 gal water/acre, or lower if label allows.






(8/15) Fruittree Leafroller 20 Online with photos at http://www.ipm.ucanr.edu/PMG/selectnewpest.nectarine.html

FRUITTREE LEAFROLLER (8/15) Scientific Name: Archips argyrospila DESCRIPTION OF THE PEST Adult fruittree leafroller moths are about 0.5 inch long, with rusty brown wings marked with areas of white and gold. When at rest the adults show the typical bell-shaped pattern common to the family Tortricidae. The eggs are laid in masses on limbs and twigs and are covered with a gray secretion that turns white upon aging. Larvae are green with a black head. The intensity of the green color varies from a light green in young larvae to a darker green as they mature. Fruittree leafroller larvae are difficult to distinguish from the more damaging obliquebanded leafroller larvae. The fruittree leafroller overwinters in the egg stage. Eggs usually hatch in early spring. Larvae feed within opening buds. As they mature they tie leaves together and feed on leaves, blossoms, and small fruit. Adults emerge in May or June. These adults then lay egg masses that overwinter. There is one generation per year. DAMAGE Fruittree leafroller damage consists of feeding on blossoms as well as leaves and developing fruit. Rarely are populations heavy enough to cause a reduction in the crop, but this pest can leave unsightly surface feeding scars on the fruit that increase in size as the fruit enlarges, causing it to be culled before packing. MANAGEMENT Delayed-dormant treatments and bloom time applications for other pests help keep leafroller populations under control. However, regular monitoring each season is important so that prompt action can be taken if damaging populations develop. In spring, watch for the presence of fruittree leafroller larvae while monitoring for other pests. This is especially important in orchards where bloom time sprays and pheromone confusion are used to control peach twig borer and oriental fruit moth. Biological Control A number of parasites, including species of Macrocentrus, Apanteles, and Exochus, attack leafroller larvae. General predators such as lacewings, assassin bugs, and minute pirate bugs may feed on eggs and larvae. Preservation of natural enemy populations is an important part of keeping leafroller numbers low. Use selective materials that are least disruptive of biological control when treating other pests. Organically Acceptable Methods Fruittree leafroller can be managed organically with certain oil sprays during the dormant season followed by bloom treatments of Bacillus thuringiensis or the Entrust formulation of spinosad. These treatments are also used to manage other leafrollers and peach twig borer. Always check with your certifier as to which oils are organically acceptable. Monitoring and Treatment Decisions Although a separate treatment for fruittree leafroller control is seldom needed, inspect orchards during the dormant period for unusually large numbers of egg masses. Egg masses are about the size of a thumbprint and laid on smooth wood. Also check flowers during bloom for the presence of the fruittree leafroller and other larvae (see EARLY-SEASON MONITORING for details). If damaging populations are observed, a number of environmentally friendly chemicals are effective in controlling this pest, including Bacillus thuringiensis, spinetoram (Delegate), spinosad (Entrust, Success), and methoxyfenozide (Intrepid). Take a fruit damage sample at harvest to assess the effectiveness of the current year's IPM program and to determine the needs of next year's program. (For procedures see FRUIT EVALUATION AT HARVEST.) Record results for harvest sample. (Example form available online)







DORMANT OR DELAYED-DORMANT A. NARROW RANGE OIL# (440 or higher) 4–6 gal 1–1.5 gal 12 0 MODE OF ACTION: Contact including smothering and barrier effects. COMMENTS: Choose a narrow range oil with a 50% distillation point of 440 or higher for dormant season use.

Always check with your certifier as to which oils are organically acceptable. Oil used alone will provide only partial control. Best when followed by an application of Bacillus thuringiensis or other environmentally sound insecticides at bloom.

B. NARROW RANGE OIL (440 or higher) 4–6 gal 1–1.5 gal 4 0 MODE OF ACTION: Contact including smothering and barrier effects. . . . PLUS . . . DIFLUBENZURON* (Dimilin 2L) 8–16 fl oz/acre 12 0 MODE-OF-ACTION GROUP NUMBER1: 15 COMMENTS: Apply in sufficient water to ensure good coverage. Choose a narrow range oil with a 50% distillation

point of 440 or higher for dormant season use. Apply with narrow range oil at 1.5% oil by volume. . . . or . . . SPINOSAD (Entrust)# 1.25–2.5 oz 0.42–0.83 oz 4 1 (Success) 4–8 oz 1.3–2.7 oz 4 1 MODE-OF-ACTION GROUP NUMBER1: 5 COMMENTS: Toxic to bees; do not spray directly or allow to drift onto blooming crops or weeds where bees are

foraging. . . . or . . . SPINETORAM (Delegate WG) 4.5–7 oz/acre 4 1 MODE-OF-ACTION GROUP NUMBER1: 5 COMMENTS: Toxic to bees; do not spray directly or allow to drift onto blooming crops or weeds where bees are

foraging.

BLOOM A. SPINOSAD (Entrust)# 1.25–2.5 oz 0.42–0.83 oz 4 1 (Success) 4–8 oz 1.3–2.7 oz 4 1 MODE-OF-ACTION GROUP NUMBER1: 5 COMMENTS: Most affective when applied at petal fall. This product is toxic to bees for 3 hours following treatment;

apply in the late evening after bees have stopped foraging. Do not apply more than 29 oz/acre per year of Success or 9 oz/acre per year of Entrust. Toxic to bees; do not spray directly or allow to drift onto blooming crops or weeds where bees are foraging.

B. METHOXYFENOZIDE (Intrepid 2F) 8–16 oz/acre 4 7 MODE-OF-ACTION GROUP NUMBER1: 18 COMMENTS: Apply at petal fall. Do not apply more than 16 fl oz/acre per application or 64 fl oz/acre per season. C. CHLORANTRANILIPROLE (Altacor) 3–4.5 oz/acre 4 10 MODE-OF-ACTION GROUP NUMBER1: 28 COMMENTS: Do not use more than 4.5 fl oz/acre per application or more than 9 fl oz/acre per season. D. SPINETORAM (Delegate WG) 4.5–7 oz 4 1 MODE-OF-ACTION GROUP NUMBER1: 5 COMMENTS: Toxic to bees; do not spray directly or allow to drift onto blooming crops or weeds where bees are

foraging.






UPDATED 8/15 E. BACILLUS THURINGIENSIS ssp. KURSTAKI# (various products) Label rates 4 0 MODE-OF-ACTION GROUP NUMBER1: 11A COMMENTS: Make two applications during bloom: the first between popcorn and the beginning of bloom and the

second 7–10 days later, but no later than petal fall. Compatible with fungicide sprays, and can be tank mixed with them. Good coverage is essential. Ground application using a concentrate rate (80–100 gal water maximum) is preferred. If aerial applications must be made because conditions do not permit ground application, a concentrate rate (5 gal or less) is preferred. Fly material on at a height of about 20 ft over the canopy using appropriate nozzles to allow better deposition on the treetops. Precede this treatment with an oil spray during the delayed-dormant season to control San Jose scale and European red mite eggs



* Permit required from county agricultural commissioner for purchase or use. # Acceptable for use on organically grown produce.

— Not recommended or not on label. 1 Rotate chemicals with a different mode-of-action Group number, and do not use products with the same mode-of-action

Group number more than twice per season to help prevent the development of resistance. For example, the organophosphates have a Group number of 1B; chemicals with a 1B Group number should be alternated with chemicals that have a Group number other than 1B. Mode of action Group numbers are assigned by IRAC (Insecticide Resistance Action Committee). For additional information, see their Web site at http://www.irac-online.org/.


(8/15) Katydids 23 Online with photos at http://www.ipm.ucanr.edu/PMG/selectnewpest.nectarine.html

KATYDIDS (8/15) Scientific Names: Angularwinged katydid: Microcentrum retinerve Forktailed bush katydid: Scudderia furcata DESCRIPTION OF THE PESTS Of the two species of katydids found in California stone fruit orchards, the forktailed katydid occurs most frequently. Both angularwinged nymphs and adults have a distinct humpbacked appearance. The forktailed bush katydid is smaller and not humpbacked. Nymphs of both species have very long antennae that are banded black and white. Katydids lay disc-shaped eggs in fall. The eggs of the angularwinged katydid are 0.125 to 0.15 inch long (3–6 mm), gray, and laid in two overlapping rows that form a long “tent" on the surface of twigs and branches. Forktailed bush katydid eggs are about 0.125 inch long (3 mm) and are inserted into the edges of leaves. Eggs of both species hatch in April and May. Adult katydids appear in midsummer and lay eggs from summer to fall. The angularwinged katydid emerges in May and has only one generation a year. Forktailed bush katydids emerge about a month earlier than the angularwinged species. Eggs are laid in June and July. Some of these eggs will hatch in July and August, whereas the rest will overwinter. DAMAGE Katydids often become damaging pests in orchards that have not been treated with broad-spectrum pesticides or where tillage is not used. High populations of these pests also occur in cycles, and they may cause damage one year and not the next. Nymphs feed on leaves or fruit. Katydid nymphs tend to feed on a small section of a fruit (about 0.5 inch wide and 0.25 inch deep) before moving on to another feeding site. Hence, a few katydids may damage a large number of fruit in a short time. Feeding wounds heal over and enlarge into corky patches as the fruit expands. Damage to a young fruit can cause it to become severely distorted as it develops. Nymphs and adults also chew holes in foliage. Smaller nymphs feed in the middle of the leaf, creating small holes, whereas larger nymphs and adults feed on the leaf edge. Damage to fruit and foliage can resemble that of green fruitworms. MANAGEMENT Look for katydid damage when monitoring for leafrollers in spring (see EARLY SEASON MONITORING). Also, use a sweep net to detect populations in the orchard cover crop. It is important to treat populations early in the season if they have been a problem in the past and are detected in the orchard. Adult katydids migrate readily from adjacent orchards, and late season fruit is particularly susceptible to feeding. From April to May, examine leaves on shoots in the center of the tree for feeding damage. Early in the season when katydids are small, they create small holes in the center of the leaf, whereas cutworms and other leaf feeders will be feeding on the leaf edge. Look at 50 trees throughout the orchard and examine each tree for 30 seconds. If you find feeding damage, look for nymphs by shaking foliage onto large beating sheets; nymphs can be difficult to see on the tree. Generally, treatment may be necessary if any of the foliage examined has feeding damage. Examine fruit on trees every week after color break (see PREHARVEST FRUIT SAMPLES) to detect any developing problems in the orchard. Take a fruit damage sample at harvest to assess the effectiveness of the current year's IPM program and to determine the needs of next year's program (see FRUIT EVALUATION AT HARVEST). Record results for harvest sample. (Example form available online)


(8/15) Katydids 24 Online with photos at http://www.ipm.ucanr.edu/PMG/selectnewpest.nectarine.html




UPDATED 8/15 The following are ranked with the pesticides having the greatest IPM value listed first—the most effective and least harmful to natural enemies and honey bees, and the environment are at the top of the table. When choosing a pesticide, consider information relating to air and water quality, resistance management, and the pesticide's properties and application timing. Not all registered pesticides are listed. Always read the label of the product being used. A. CHLORANTRANILIPROLE (Altacor) 3–4.5 oz/acre 4 10 MODE-OF-ACTION GROUP NUMBER1: 28 COMMENTS: For best results, apply in 100 to 150 gal water/acre. B. PHOSMET (Imidan 70-W) 2 1/8–4 ¼

lb ¾–1 lb 168 (7 days) 14

MODE-OF-ACTION GROUP NUMBER1: 1B COMMENTS: Effective against nymphs and adults. Highly toxic to bees; do not spray directly or allow to drift onto

blooming crops or weeds where bees are foraging. C. SPINETORAM (Delegate WG) 4.5–7 oz/acre 4 1 MODE-OF-ACTION GROUP NUMBER1: 5 COMMENTS: Toxic to bees; do not spray directly or allow to drift onto blooming crops or weeds where bees are

foraging. D. INDOXACARB (Avaunt) 6 oz — 12 14 MODE-OF-ACTION GROUP NUMBER1: 22A COMMENTS: Apply in no more than 200 gal/acre. Highly toxic to bees; do not spray directly or allow to drift onto

blooming crops or weeds where bees are foraging. E. SPINOSAD (Entrust)# 1.25–2 oz 0.42–0.83 oz 4 1 (Success) 4–8 oz 1.3–2.7 oz 4 1 MODE-OF-ACTION GROUP NUMBER1: 5 COMMENTS: Apply to young nymphs (1st and 2nd instars). Not as effective on adults. Toxic to bees; do not spray

directly or allow to drift onto blooming crops or weeds where bees are foraging. F. AZADIRACHTIN# (Neemix 4.5) 0.25–1 pt 4 0 MODE-OF-ACTION GROUP NUMBER1: un COMMENTS: Moderately effective on immature katydids. Must be contacted by spray so good coverage is essential.



# Acceptable for use on organically grown produce. — Not recommended or not on label.

1 Rotate chemicals with a different mode-of-action Group number, and do not use products with the same mode-of-action Group number more than twice per season to help prevent the development of resistance. For example, the organophosphates have a Group number of 1B; chemicals with a 1B Group number should be alternated with chemicals that have a Group number other than 1B. Mode of action Group numbers (“un" =unknown or uncertain mode of action) are assigned by IRAC (Insecticide Resistance Action Committee). For additional information, see their Web site at http://www.irac-online.org/.


(8/15) Obliquebanded Leafroller 25 Online with photos at http://www.ipm.ucanr.edu/PMG/selectnewpest.nectarine.html

OBLIQUEBANDED LEAFROLLER (8/15) Scientific Name: Choristoneura rosaceana DESCRIPTION OF THE PEST Obliquebanded leafroller overwinter as third-instar larvae under bud scales. The overwintered larvae pupate in spring, and the first generation of adults emerges in late April or May. Larvae are yellowish green with brown to black heads. As they mature, larvae construct tubular shelters from a single leaf. Adults are reddish brown moths with dark brown bands on the wings. There are usually two generations a year in the Sacramento Valley and up to three in the San Joaquin Valley. DAMAGE Infestations of obliquebanded leafroller can occasionally reach damaging levels in nectarines. Larvae feed on flower parts and on fruit early in the season, causing deep depressions that eventually become rough and russeted by harvest and might be mistaken for flower thrips damage. Because of the high cyanide content of nectarine leaves, larvae generally concentrate their feeding on fruit; consequently, lower numbers of larvae may cause more damage in nectarines than in other crops. This leafroller is more damaging than fruittree leafrollers because it has one to two summer generations. MANAGEMENT Delayed-dormant treatments and bloom time applications for other pests help keep leafroller populations under control. However, regular monitoring each season is important so that prompt action can be taken if damaging populations develop. Throughout the season, watch for leafrollers while monitoring for other pests. This is especially important in orchards where bloom time sprays and pheromone confusion are used to control peach twig borer and oriental fruit moth. Degree-days For assistance in calculating degree-days, see the Obliquebanded Leafroller model on the UC IPM Web site at http://www.ipm.ucanr.edu/WEATHER/. Biological Control A number of parasites, including species of Macrocentrus, Cotesia (=Apanteles), and Exochus, attack leafroller larvae. General predators such as lacewings, assassin bugs, and minute pirate bugs may feed on eggs and larvae. Preservation of natural enemy populations is an important part of keeping leafroller numbers low. Use selective materials that are least disruptive of biological control when treating other pests. Organically Acceptable Methods Organically acceptable management tools include biological control and sprays of Bacillus thuringiensis or the Entrust formulation of spinosad. Monitoring and Treatment Decisions Check the orchard in early spring (March–April) for the presence of larvae and feeding damage on flowers (see EARLY SEASON MONITORING). If damaging populations are observed, a number of environmentally friendly insecticides are effective in controlling this pest, including Bacillus thuringiensis, spinetoram (Delegate), spinosad (Entrust, Success), and methoxyfenozide (Intrepid). The best timing for control of overwintering larvae is at full bloom or early petal fall. Pheromone traps placed in the orchard in mid-April (see PHEROMONE TRAPS) will help to monitor the population levels of this insect and provide information for management of the summer generations. Based on research done in California pistachio orchards, begin accumulating degree-days as soon as traps begin to catch moths using a lower threshold of 43°F and an upper threshold of 94°F. Make treatments between 600 and 1,000 DD. Examine fruit on trees every week after color break (see PREHARVEST FRUIT SAMPLES) to detect any developing problems in the orchard, and take a fruit damage sample at harvest to assess the effectiveness of the current year's IPM program and to determine the needs of next year's program (see FRUIT EVALUATION AT HARVEST). Record results for harvest sample. (Example form available online)







DELAYED-DORMANT A. NARROW RANGE OIL (440 or higher) 4–6 gal 1.5–2 gal 4 0 MODE OFACTION: Contact including smothering and barrier effects. . . . PLUS . . . SPINOSAD (Entrust)# 1.25–2.5 oz 0.42–0.83 oz 4 1 (Success) 4–8 oz 1.3–2.7 oz 4 1 MODE-OF-ACTION GROUP NUMBER1: 5 COMMENTS: Choose a narrow range oil with a 50% distillation point of 440 or higher for dormant season use.

Always check with your certifier as to which oils are organically acceptable. Toxic to bees; do not spray directly or allow to drift onto blooming crops or weeds where bees are foraging.

. . . or . . . SPINETORAM (Delegate WG) 4.5–7 oz/acre 4 1 MODE-OF-ACTION GROUP NUMBER1: 5 COMMENTS: Toxic to bees; do not spray directly or allow to drift onto blooming crops or weeds where bees are

foraging.

BLOOM A. SPINOSAD (Entrust)# 1.25–2.5 oz 0.42–0.83 oz 4 1 (Success) 4–8 oz 1.3–2.7 oz 4 1 MODE-OF-ACTION GROUP NUMBER1: 5 COMMENTS: Most effective when applied at petal fall. This product is toxic to bees for 3 hours following treatment;


B. CHLORANTRANILIPROLE (Altacor) 3–4.5 oz/acre 4 10 MODE-OF-ACTION GROUP NUMBER1: 28 COMMENTS: For best results, apply in 100 to 150 gal water/acre. C. METHOXYFENOZIDE (Intrepid 2F) 8–16 oz/acre 4 7 MODE-OF-ACTION GROUP NUMBER1: 18 COMMENTS: Apply at petal fall. Do not apply more than 16 fl oz/acre per application or 64 fl oz/acre per season. D. SPINETORAM (Delegate WG) 4.5–7 oz/acre 4 1 MODE-OF-ACTION GROUP NUMBER1: 5 COMMENTS: Toxic to bees; do not spray directly or allow to drift onto blooming crops or weeds where bees are foraging. E. BACILLUS THURINGIENSIS SSP. KURSTAKI# (various products) Label rates 4 0 MODE-OF-ACTION GROUP NUMBER1: 11A COMMENTS: Make two applications during bloom: the first between popcorn and the beginning of bloom and the

second 7–10 days later, but no later than petal fall. Compatible with fungicide sprays, and can be tank mixed with them. Good coverage is essential. Ground application using a concentrate rate (80–100 gal water maximum) is preferred. If aerial applications must be made because conditions do not permit ground application, a concentrate rate (5 gal or less) is preferred. Fly material on at a height of about 20 ft over the canopy using appropriate nozzles to allow better deposition on the treetops. Precede this treatment with an oil spray during the delayed-dormant season to control San Jose scale and European red mite eggs.






UPDATED 8/15

AFTER BLOOM A. SPINOSAD (Entrust)# 1.25–2.5 oz 0.42–0.83 oz 4 1 (Success) 4–8 oz 1.3–2.7 oz 4 1 MODE-OF-ACTION GROUP NUMBER1: 5 COMMENTS: Most affective when applied at petal fall. This product is toxic to bees for 3 hours following treatment;


B. METHOXYFENOZIDE (Intrepid 2F) 8–16 oz/acre 4 7 MODE-OF-ACTION GROUP NUMBER1: 18 COMMENTS: Apply at petal fall. Do not apply more than 16 fl oz/acre per application or 64 fl oz/acre per season. C. CHLORANTRANILIPROLE (Altacor) 3–4.5 oz/acre 4 10 MODE-OF-ACTION GROUP NUMBER1: 28 COMMENTS: For best results, apply in 100 to 150 gal water/acre. D. SPINETORAM (Delegate WG) 4.5–7 oz/acre 4 1 MODE-OF-ACTION GROUP NUMBER1: 5 COMMENTS: Toxic to bees; do not spray directly or allow to drift onto blooming crops or weeds where bees are

foraging. E. BACILLUS THURINGIENSIS ssp. KURSTAKI# (various products) Label rates — 4 0 MODE-OF-ACTION GROUP NUMBER1: 11A COMMENTS: Bt is a stomach poison and must be consumed by the leafroller; therefore, it is most effective when

applied during warm, dry weather when larvae are actively feeing. Most effective against young larvae. Requires more than one treatment; apply second application 7 to 10 days after first.

F. CARBARYL* (Sevin XLR Plus) 3–4 qt/acre 12 1 MODE-OF-ACTION GROUP NUMBER1: 1A COMMENTS: May cause increased spider mite problems; best used late in the season. Do not apply more than 14

qt/acre per season. Highly toxic to bees; do not spray directly or allow to drift onto blooming crops or weeds where bees are foraging.

G. PHOSMET (Imidan 70-W) 2 1/8–4 1/4

lb 3/4–1 lb 168 (7 days) 14

MODE-OF-ACTION GROUP NUMBER1: 1B COMMENTS: Highly toxic to bees; do not spray directly or allow to drift onto blooming crops or weeds where bees

are foraging.






UPDATED 8/15







(8/15) Omnivorous Leafroller 29 Online with photos at http://www.ipm.ucanr.edu/PMG/selectnewpest.nectarine.html

OMNIVOROUS LEAFROLLER (8/15) Scientific Name: Platynota stultana DESCRIPTION OF THE PEST Omnivorous leafroller is primarily a pest of nectarines in the San Joaquin Valley. It occurs in the Sacramento Valley but seldom causes damage. Omnivorous leafroller overwinters as immature larvae in mummy fruit or on winter weeds and does not enter a true dormancy. Larvae are light colored with dark brown or black heads. When mature they are about 0.6 inch long and have two slightly raised, oblong whitish spots on the upper surface of each abdominal segment. Abdominal segments may have a greenish brown tinge. They pupate inside a webbed shelter. Adults of the overwintering generation emerge by March 1. They are small, dark brown moths, 0.5 to 0.375 inch long with a dark band on the wing and a long snout. Eggs are laid in overlapping rows that resemble fish scales. The first generation of eggs usually is laid on weed hosts, but can also be found on early maturing nectarine cultivars causing moderate damage. Adults from this generation emerge in May or June to lay second-generation eggs in orchards on leaves and fruit. Larvae that hatch from this second generation of eggs can cause damage in stone fruits. Like fruittree leafroller and obliquebanded leafroller, they have the characteristic behavior of wriggling backward when disturbed and dropping from a silk thread attached to the leaf or fruit surface. DAMAGE Omnivorous leafroller larvae often web leaves into rolled protective shelters while feeding. They feed on leaves and on the surface of fruit, sometimes webbing one or more leaves to the fruit for protection. They chew shallow holes or grooves in the fruit surface, often near the stem end, and webbing is usually present on fruit. Damage results from fruit feeding. Young fruit may be destroyed, and scars on older fruit will cause them to be culled or downgraded at harvest. Feeding injury also may increase the incidence of brown rot and other fruit decays. MANAGEMENT Omnivorous leafrollers can be found in orchards in the spring, but the majority of damage occurs during the summer. Regular monitoring each season is important so that prompt action can be taken if damaging populations develop. Throughout the season, watch for the presence of leafroller larvae while monitoring. Degree-days For assistance in calculating degree-days, see the Omnivorous Leafroller model on the UC IPM Web site at http://www.ipm.ucanr.edu/WEATHER/. Biological Control A number of parasites, including species of Macrocentrus, Cotesia (Apanteles), and Exochus, attack omnivorous leafroller larvae. General predators such as lacewings, Phytocoris bugs, assassin bugs, and minute pirate bugs may feed on eggs and larvae. Preservation of natural enemy populations is an important part of keeping leafroller numbers low. Use selective pesticides that are least disruptive of biological control when treating other pests. Cultural Control Remove and destroy fruit mummies; also destroy potential overwintering weed hosts, such as horseweed, common lambsquarters, little mallow, curly dock, and legumes, by clean cultivation. Organically Acceptable Methods Biological and cultural control along with applications of Bacillus thuringiensis and the Entrust formulation of spinosad are organically acceptable tools. Monitoring and Treatment Decisions Begin monitoring by placing pheromone monitoring traps in the orchard by February 20 in the San Joaquin Valley and check twice weekly to establish the biofix for the first flight (overwintering generation), which should occur around March 1; biofix is the first night moths are consistently caught in traps over a period of several nights (see PHEROMONE TRAPS). From the first biofix, accumulate degree-days (DD) to estimate when to apply



a treatment. Use a lower threshold of 48°F and an upper threshold of 87°F. Optimum treatment timing is between 700 and 900 DD after the first biofix. Estimate the onset of the second flight (first generation adults) by accumulating degree-days from the first biofix. The second flight begins approximately 1168 DD after the first biofix, because this is how long it takes the omnivorous leafroller to develop from egg to adult. As the start of the second flight nears, be sure to have fresh trap liners and lures in place. When the second flight biofix is determined by trap catches, begin accumulating degree-days. If necessary, apply an insecticide for the second larval generation between 700 and 900 DD after the start of the second flight biofix. Monitor the fruit closely for signs of damage. No treatment threshold values are available. Examine fruit on trees every week after color break (see PREHARVEST FRUIT SAMPLES) to detect any developing problems in the orchard. Take a fruit damage sample at harvest to assess the effectiveness of the current year's IPM program and to determine the needs of next year's program (see FRUIT EVALUATION AT HARVEST). Record results for harvest sample. (Example form available online)




UPDATED 8/15 The following are ranked with the pesticides having the greatest IPM value listed first—the most effective and least harmful to natural enemies and honey bees, and the environment are at the top of the table. When choosing a pesticide, consider information relating to air and water quality, resistance management, and the pesticide's properties and application timing. Not all registered pesticides are listed. Always read the label of the product being used. A. SPINOSAD (Entrust)# 1.25–2.5 oz 0.42–0.83 oz 4 1 (Success) 4–8 oz 1.3–2.7 oz 4 1 MODE-OF-ACTION GROUP NUMBER1: 5 COMMENTS: Do not apply more than 29 oz/acre per year of Success or 9 oz/acre per year of Entrust. Toxic to bees;

do not spray directly or allow to drift onto blooming crops or weeds where bees are foraging. B. CHLORANTRANILIPROLE (Altacor) 3–4.5 oz/acre 4 10 MODE-OF-ACTION GROUP NUMBER1: 28 COMMENTS: For best results, apply in 100 to 150 gal water/acre. C. METHOXYFENOZIDE (Intrepid 2F) 8–16 oz/acre 4 7 MODE-OF-ACTION GROUP NUMBER1: 18 COMMENTS: Do not apply more than 16 fl oz/acre per application or 64 fl oz/acre per season. D. SPINETORAM (Delegate WG) 4.5–7 oz/acre 4 1 MODE-OF-ACTION GROUP NUMBER1: 5 COMMENTS: Toxic to bees; do not spray directly or allow to drift onto blooming crops or weeds where bees are

foraging. E. BACILLUS THURINGIENSIS ssp. KURSTAKI# (various products) Label rates 4 0 MODE-OF-ACTION GROUP NUMBER1: 11A COMMENTS: Good coverage is essential. Ground application using a concentrate rate (80–100 gal water maximum)

is preferred. If aerial applications must be made because conditions do not permit ground application, a concentrate rate (5 gal or less) is preferred. Fly material on at a height of about 20 ft over the canopy using appropriate nozzles to allow better deposition on the treetops.






UPDATED 8/15

** For dilute applications, rate is per 100 gal water to be applied in 300-500 gal water/acre, according to label; for concentrate applications, use 80–100 gal water/acre, or lower if label allows.

‡ Preharvest interval. Do not apply within this many days of harvest. # Acceptable for use on organically grown produce.

— Not recommended or not on label. 1 Rotate chemicals with a different mode-of-action Group number, and do not use products with the same mode-of-action



(8/15) Oriental Fruit Moth 32 Online with photos at http://www.ipm.ucanr.edu/PMG/selectnewpest.nectarine.html

ORIENTAL FRUIT MOTH (8/15) Scientific Name: Grapholitha molesta DESCRIPTION OF THE PEST Adult oriental fruit moths are small, grayish moths about 0.4 inches long. These moths normally fly in the evenings just after sunset, or occasionally between daybreak and sunrise. Eggs are laid usually on the top of leaves and are disk-shaped, white to creamy in color when first laid, and about 0.03 inch in diameter. Just before hatching, the black head of the developing larva becomes visible. Larvae are white with a black head when first hatched. As they mature, they gradually turn pink with a brown head. Mature larvae are about 0.5 inch long. Use a hand lens to detect the presence of an anal comb under the last abdominal sclerite, which helps distinguish oriental fruit moth from other white or pink worms, such as codling moth, that may be found in stone fruits. There are usually five generations per year in California, although a sixth-generation has been observed in years with warm weather in early spring and late fall. Oriental fruit moths overwinter as mature, diapausing larvae inside tightly woven cocoons in protected places on the tree or in the trash near the base of the tree. In early spring, pupation takes place inside the cocoon and adults begin emerging in February or early March. Eggs are deposited on newly emerged shoots and the larva feed in terminals where they complete their development. Second-generation larvae feed in shoots, but fruit of some of the earlier-maturing nectarine cultivars may also be attacked. Subsequent generations may attack shoot terminals and green fruit, but as fruit matures it becomes the preferred site of attack by this pest. Generally oriental fruit moth larvae bore deeper into the shoot than peach twig borer larvae do, and push granular frass out of the tunnel where it can often be seen. If the larvae are still present, cut strikes open and look for larvae to determine if the infestation is oriental fruit moth or peach twig borer. DAMAGE Larvae damage developing shoots and fruit. Feeding on shoots kills the tip of the shoot, causing typical shoot strikes or flagging. However, the most severe damage occurs where larvae feed on fruit, causing it to be rated offgrade. Small larvae generally enter the fruit at the stem end, although entry can be made anywhere on the fruit, particularly where two fruits touch. Larvae immediately bore to the center of the fruit and feed around the pit. After reaching maturity, they exit from the fruit and pupate. MANAGEMENT Use of mating disruptants is the preferred management strategy for oriental fruit moth. Alternatively, insecticide sprays timed according to degree-day accumulations can be used. There are many newly registered, less disruptive and very effective insecticides that can be well integrated into an IPM Program. Careful monitoring is critical to the success of management tools. Degree-days For assistance in calculating degree-days, see the Oriental Fruit Moth model on the UC IPM Web site at http://www.ipm.ucanr.edu/WEATHER/. Biological Control The parasite Macrocentrus ancylivorus is a common parasite of oriental fruit moth larvae and peach twig borer larvae. In orchards when broad-spectrum insecticides are not used, parasitism can reach levels of 80 to 90% by August and September and help to provide long-term control of this pest. Preliminary studies indicate that growing a small (0.3-0.5 acre) plot of sunflowers can provide Macrocentrus with an overwintering host, the sunflower moth Homoeosoma electellum, which allow its populations to build more rapidly in the orchard the following season. Planting sunflowers in a staggered planting in April and again in late May has proven to be a useful strategy. Organically Acceptable Methods Mating disruptant dispensers and sprays of the Entrust formulation of spinosad are organically acceptable; sprayable pheromones and puffers may not be accepted by certifiers.



Monitoring and Treatment Decisions Mating Disruption Orchards Mating disruption is very effective for the first two generations and into the third-generation. (Later generations are controlled, but not as consistently.) In most cases mating disruption can eliminate the need for insecticide sprays. To control oriental fruit moth by disrupting mating, put pheromone traps in the orchard by February 15 to detect the first moth emergence (see PHEROMONE TRAPS). As soon as moths have emerged, put out the mating disruption pheromone dispensers. (In orchards where mating disruption was used the previous year, be sure to place new dispensers in the orchard no later than March 5. In some cases pheromone traps may fail to catch the first moth if dispensers from the previous year are still emitting pheromones.) Depending on the duration of effectiveness for the dispensers, a second application of pheromone is needed in late July to early August for later-maturing varieties. (Sprayable pheromones may either be used for the first flight or substituted for the second application of pheromones dispensers.) In orchards with high populations of the parasite, Macrocentrus ancylivorus, a second application of pheromone dispensers may not even be necessary. This parasite, however, will not be abundant in orchards where a broad-spectrum insecticide has been used. Pheromone-treated orchards must be carefully monitored for peach twig borer, oriental fruit moth, and other pests that can move in from neighboring stone fruit and almond orchards. Use pheromone traps as a backup to detect how well mating disruption is working. When no moths are caught in pheromone traps, it is a good indication that mating is being disrupted. However, also monitor shoot strikes to ensure the effectiveness of mating disruption. Monitor shoot strikes (see SHOOT STRIKE MONITORING) in late April, mid-June, and mid-July, and sample fruit every week (with an emphasis on the final 4 weeks before harvest) (see PREHARVEST FRUIT SAMPLES). If an orchard has more than an average of three shoot strikes per tree or if you find any larvae in the fruit, plan to treat the succeeding generation with an insecticide. Conventional Orchards If you choose to manage oriental fruit moth with insecticides, use pheromone traps to monitor emergence of the second flight (late April to early May) to get a biofix. (Generally no insecticide treatment is applied to the first generation, except where populations are excessive, because of the erratic emergence and oviposition caused by variable weather conditions.) Use SHOOT STRIKE MONITORING and FRUIT MONITORING to determine need for treatment. Put pheromone traps in the orchard by February 15 to detect when moths emerge for the first flight (see PHEROMONE TRAPS). Once the first moth is trapped, accumulate degree-days (DD) to estimate when the onset of the second flight will occur. Use a lower threshold of 45°F and an upper threshold of 90°F. The second flight should begin about 920 to 1,010 DD from the beginning of the initial flight; in some areas, however, the second flight may be seen as early as 800 DD. Once the second flight has started, usually in May, accumulate degree-days. If a spray of methoxyfenozide (Intrepid) or chlorantraniliprole (Altacor) is planned, treat at 400 DD from the first trapped moth, otherwise, apply treatments from 500 to 600 DD. Treat at 400 to 500 DD for the third or fourth flight as fruit ripens. Monitor moths until the crop is harvested in order to detect late-season peaks or migrations of moths from adjacent orchards. In orchards with heavy infestations, additional sprays will be needed to prevent fruit damage at harvest. Sprays must be carefully timed to kill newly hatched larvae before they bore into shoots or fruit. If treatments are needed for the third and fourth flights, spray at 400 to 500 DD after the start of the flight. Also, monitor fruit for the presence of worms. Generally fruit is most heavily attacked in the tops of the trees, so fruit samples should be picked and examined from that area. Although green fruit can be attacked, fruit is most susceptible to attack by oriental fruit moth after color break. Treat if larvae are found in fruit. All Orchards Examine fruit on trees every week after color break (see PREHARVEST FRUIT SAMPLES) to detect any developing problems in the orchard, and take a fruit damage sample at harvest to assess the effectiveness of the current year's IPM program and to determine the needs of next year's program (see FRUIT EVALUATION AT HARVEST). Record results for harvest sample. (Example form available online)



The following are ranked with the pesticides having the greatest IPM value listed first—the most effective and least harmful to natural enemies and honey bees, and the environment are at the top of the table. When choosing a pesticide, consider information relating to air and water quality, resistance management, and the pesticide's properties and application timing. Not all registered pesticides are listed. Always read the label of the product being used. UPDATED 8/15 Common name (Example trade name) Dispensers per acre**

General Duration of Effectiveness (days)2

A. MATING DISRUPTANTS (Checkmate OFM Dispenser)# 100–200 dispensers (1/tree) 90 (Checkmate OFM–O Puffer)# 40 acres (1–2/acre)

< 40 acres (2/acre) 200

(Checkmate OFM-F) 1.32–2.93 fl oz/acre 14–30 (Checkmate OFM-SL‡)# 100–250 dispensers/acre 180 (Checkmate SF) 150–200 dispensers/acre 90 (Isomate M Rosso)# 100–200 dispensers/acre 150 (Isomate OFM TT)# 100 dispensers/acre 180 COMMENTS: Apply just before or at first moth emergence in spring. Place dispensers in upper one-third of the tree

canopy and apply extra dispensers to trees on the orchard's perimeter. Replace at the beginning of the second flight or in 3 months for 90-day products, whichever occurs first. Apply flowable every 30 days and more frequently in hot weather; apply with Nu-Film P sticker. (Flowable pheromone is not organically acceptable.) Check with certifier to determine which products are organically acceptable.




UPDATED 8/15 B. CHLORANTRANILIPROLE (Altacor) 3–4.5 oz/acre 4 10 MODE-OF-ACTION GROUP NUMBER1: 28 COMMENTS: Because it impacts egg hatch, apply 400 DD after first trap catch. Do not use more than 4.5 fl oz/acre

per application or more than 9 fl oz/acre per season or apply in more than 200 gal/acre. C. METHOXYFENOZIDE (Intrepid 2F) 10–16 fl oz/acre 4 7 MODE-OF-ACTION GROUP NUMBER1: 18 COMMENTS: Because it impacts egg hatch, apply 400 DD after first trap catch. Do not used more than 16 fl oz/acre

per application or more than 64 fl oz/acre per season. D. SPINETORAM (Delegate WG) 6–7 oz/acre 4 1 MODE-OF-ACTION GROUP NUMBER1: 5 COMMENTS: Toxic to bees; do not spray directly or allow to drift onto blooming crops or weeds where bees are

foraging. E. PHOSMET (Imidan 70-W) 2.125–4.25 lb 0.75–1 lb 168 (7 days) 14 MODE-OF-ACTION GROUP NUMBER1: 1B COMMENTS: Highly toxic to bees; do not spray directly or allow to drift onto blooming crops or weeds where bees

are foraging.






UPDATED 8/15 F. INDOXACARB (Avaunt) 6 oz /acre 12 14 MODE-OF-ACTION GROUP NUMBER1: 22A COMMENTS: Also controls katydids and small plant bugs. Do not apply in more than 200 gal/acre. Highly toxic to

bees; do not spray directly or allow to drift onto blooming crops or weeds where bees are foraging. G. ESFENVALERATE* (Asana XL) 4.8–14.5 fl oz 2–5.8 fl oz 12 14 MODE-OF-ACTION GROUP NUMBER1: 3A COMMENTS: The use of esfenvalerate is not generally recommended on perennial crops in the San Joaquin Valley

because high label rates can cause outbreaks of secondary pests. While low label rates reduce the potential for secondary outbreaks in the Sacramento Valley, they should only be used where resistance to organophosphates has not become a problem and other methods such as mating disruption are not feasible. Highly toxic to bees; do not spray directly or allow to drift onto blooming crops or weeds where bees are foraging.

H. SPINOSAD (Entrust)# 1.25–2.5 oz 0.42–0.83 oz 4 1 (Success) 4–8 oz 1.3–2.7 oz 4 1 MODE-OF-ACTION GROUP NUMBER1: 5 COMMENTS: Works well as a supplement in a mating disruption program. This product is toxic to bees for 3 hours

following treatment; apply in the late evening after bees have stopped foraging. Do not apply more than 29 oz/acre per year of Success or 9oz/acre per year of Entrust.

I. CARBARYL* (Sevin XLR Plus) 3–4 qt/acre 12 1 MODE-OF-ACTION GROUP NUMBER1: 1A COMMENTS: May cause increased spider mite problems; best used late in the season. Not recommended for routine

use, especially early in the season. Do not apply more than 14 qt/acre per season. Highly toxic to bees; do not spray directly or allow to drift onto blooming crops or weeds where bees are foraging.





Group number more than twice per season to help prevent the development of resistance. For example, the organophosphates have a Group number of1B; chemicals with a 1B Group number should be alternated with chemicals that have a Group number other than 1B. Mode of action Group numbers are assigned by IRAC (Insecticide Resistance Action Committee). For additional information, see their Web site at http://www.irac-online.org/.

2 Actual length of effectiveness can vary depending on environmental conditions and insect populations.


(8/15) Pacific Flatheaded Borer 36 Online with photos at http://www.ipm.ucanr.edu/PMG/selectnewpest.nectarine.html

PACIFIC FLATHEADED BORER (8/15) Scientific Name: Chrysobothris mali DESCRIPTION OF THE PEST The Pacific flatheaded borer overwinters in the prepupal stage. Pupation occurs in spring, and beetles begin to emerge in April. Adult beetles are flattened and vary in length from 0.5 to 0.75 inch. They are dark bronze with coppery spots on the wing covers, giving a coppery sheen to the elytra. The head and thorax are almost as wide as the abdomen, forming a wedge shape. Adult emergence continues until July, which accounts for the various- size larvae found during summer. After emergence, female beetles mate and lay eggs on the bark, usually in sites exposed to the sun or weakened limbs. Eggs are circular, flattened, whitish, and about 0.04 inch in diameter. Upon hatching, larvae bore through the bottom of the egg directly into the bark. Almost all of the larval period is spent feeding in the cambium layer of the bark. When the larva reaches maturity, it either bores into the xylem and constructs an oval pupal chamber or pupates just under the bark where it stays in the prepupal stage until the following spring. Mature larvae are about 0.75 inch long and whitish in color. The body is flattened, and the head is amber colored. The larvae have a broad flat area behind the head, and the body tapers toward the posterior. The typical beetle like pupa is also quite flat. It is creamy white when first formed but darkens as the time approaches for emergence to an adult. DAMAGE The Pacific flatheaded borer prefers weak or injured trees. Newly planted or grafted trees are particularly susceptible to attack because of the stress caused by planting and the possibility of sunburn on the bark and at the bud union. The larvae feed in the cambium and can completely girdle and kill young or newly grafted trees in a short period of time. Limbs of older trees (particularly if sunburned) are also attacked, but they rarely die from flatheaded borer attack. However, older limbs can be weakened to such an extent that other borers such as the shothole borer can attack successfully. MANAGEMENT Maintaining healthy trees and preventing sunburn are the keys to preventing damage by Pacific flatheaded borer. Painting the trees with white wash or a 50:50 mixture of white interior latex paint and water will help prevent sunburn and possibly inhibit egg laying. Avoid pruning during summer, and prune trees so that scaffolds are shaded to prevent sunburn. Remove horizontal scaffolds when pruning or thinning young trees. Protect newly planted or newly grafted trees from sunburn by painting the trunk and graft with white interior latex paint or using tree wrappers around the trunk. If paint is used, be sure to mix it with water; undiluted latex paint can kill young trees. Thin the latex paint to a mixture of one-half water and one-half latex paint and paint the trunk from 2 inches below ground level to 2 feet above. In older orchards, monitor for flatheaded borers by looking for water soaked areas on the bark. As injury progresses, the bark will split, exposing the frass-filled feeding galleries. Paint the exposed upper sides of scaffolds particularly on the north and east side of older trees to prevent sunburn and subsequent flatheaded borer attack.


Amount to use

UPDATED 8/15 The following are ranked with the pesticides having the greatest IPM value listed first—the most effective and least harmful to natural enemies and honey bees, and the environment are at the top of the table. When choosing a pesticide, consider information relating to air and water quality, resistance management, and the pesticide's properties and application timing. Not all registered pesticides are listed. Always read the label of the product being used. A. WHITE LATEX PAINT# 50% paint and water mixture COMMENTS: Paint trees at time of planting. Be sure paint extends below ground level. This treatment will prevent

sunburn, which can reduce attack by flatheaded borer.

# Acceptable for use on organically grown produce.


(8/15) Peach Silver Mite 37 Illustrated version athttp://www.ipm.ucanr.edu/PMG/selectnewpest.nectarine.html

PEACH SILVER MITE (8/15) Scientific Name: Aculus cornutus DESCRIPTION OF THE PEST Peach silver mites are tiny, four-legged eriophyid mites, yellow to pinkish white, and somewhat wedge shaped, being broadest just behind the anterior end. Because they are so tiny, they are difficult to see without a hand lens of at least 10X power. Peach silver mites overwinter as females in bark crevices, around buds, and under bud scales. They move to leaves soon after budbreak in spring. These mites can also be found on small fruit, often inhabiting the area between the calyx and the fruit. Later in the season they are found primarily on the lower leaf surface. Before leaf fall, females move to overwintering sites. Many generations are produced during the season. DAMAGE On rare occasions when very high populations of peach silver mite survive the winter, they produce symptoms on the unfolding leaves. Symptoms consist of minute, yellow spots and a tendency for the leaf edges to curl toward the midrib. Ordinarily, however, most injury is not noticed until mid- to late summer when heavily infested leaves take on a silvery appearance. MANAGEMENT Treatments applied specifically for control of peach silver mite are rarely needed and should be avoided because peach silver mites serve as early season food for predaceous mites, which in turn aid in reducing populations of other pest mites. The use of broad-spectrum insecticides for other pests can cause high infestations of peach silver mite. Organically Acceptable Methods Sulfur sprays are acceptable for organically certified crops, but will reduce predator mite populations. Monitoring and Treatment Decisions If heavy populations (200–300 per leaf) of peach silver mite are present and causing damage, consider applying sulfur or miticides used for control of other mite species. Some insecticides applied for control of other pests eliminate peach silver mites as well.




UPDATED 8/15 The following are ranked with the pesticides having the greatest IPM value listed first—the most effective and least harmful to natural enemies and honey bees, and the environment are at the top of the table. When choosing a pesticide, consider information relating to air and water quality, resistance management, and the pesticide's properties and application timing. Not all registered pesticides are listed. Always read the label of the product being used. A. WETTABLE SULFUR# — 5 lb 24 0 MODE OF ACTION: Unknown. An inorganic miticide. COMMENTS: Do not apply within 2 weeks of oil spray. May reduce predator mite populations.





(8/15) Peach Twig Borer 38 Online with photos at http://www.ipm.ucanr.edu/PMG/selectnewpest.nectarine.html

PEACH TWIG BORER (8/15) Scientific Name: Anarsia lineatella DESCRIPTION OF THE PEST Small peach twig borer larvae are almost white with a distinct black head. As larvae mature they become chocolate brown with alternating dark and light bands around the abdomen. The light, intersegmental membranes contrasted with the brown body distinguishes peach twig borer from other larvae found in stone fruits. Mature larvae are about 0.5 inch long. Pupae are 0.25 to 0.4 inch long, brown in color and lack a cocoon. Pupation takes place in protected places on the tree and occasionally in the stem cavity of infested fruit. Adult peach twig borer moths are 0.3 to 0.4 inch long with steel gray, mottled forewings. The long, narrow forewings are lightly fringed; the lighter gray hindwings are more heavily fringed. Prominent palpi on the head give the appearance of a snout. The bluntly oval eggs are yellowish to orange and are laid on twigs, leaves, or on the fruit surface. Peach twig borer overwinters on the tree as a first- or second-instar larva within a tiny cell, called a hibernaculum, that is located in crotches of 1- to 3-year-old wood, in pruning wounds, or in deep cracks in bark. The overwintering site is marked by a chimney of frass and is especially noticeable when first constructed or before winter rains set in. Larvae emerge in early spring, usually just before and during bloom, and migrate up twigs and branches where they attack newly emerged leaves, blossoms, and shoots. As shoots elongate, larvae mine the inside, causing the terminals to die back. Dead shoots are known as shoot strikes or flags. Adults from the overwintered generation usually begin emerging in April or early May. First-generation larvae usually develop in twigs during May and June and give rise to the next flight of moths in late June or early July. Larvae from this and subsequent generations may attack either twigs or fruit depending on fruit maturity and population density. DAMAGE Peach twig borer can damage stone fruits by feeding in shoots and causing shoot strikes, or by feeding directly on the fruit. Shoot damage is most severe on the vigorous growth of young, developing trees because feeding kills the terminal growth and can result in undesirable lateral branching. As fruit matures, it becomes highly susceptible to attack; damage is most likely to occur from color break to harvest. Twig borer larvae generally enter fruit at the stem end or along the suture and usually feed just under the skin. MANAGEMENT Within an IPM program, the preferred management strategy for peach twig borer is well-timed treatments of environmentally sound insecticides around bloom time. These include Bacillus thuringiensis, spinosad (Entrust, Success), methoxyfenozide (Intrepid), and diflubenzuron (Dimilin). Bloom time applications integrate well with brown rot treatment, thus helping to cut application costs. Bloom sprays are preferred over in-season sprays in an IPM program because they have less adverse impact on beneficials and nontarget organisms. Alternatively, peach twig borer can be controlled with a spray in the delayed-dormant season to kill overwintering larvae in the hibernacula. Organophosphates and pyrethroid insecticides have traditionally been used but these should be avoided because they pose surface water quality concerns and may pose some risks to raptors, aquatic invertebrates, beneficials, and other nontarget organisms. Dormant sprays of oil plus spinetoram (Delegate) spinosad (Entrust, Success) or diflubenzuron (Dimilin) do not present these environmental problems. Dormant sprays of oil alone or oil combined with an insecticide, however, have the advantage of controlling some other stone fruit pests, especially mites and San Jose scale. (Oil alone does not control peach twig borer.) Mating disruption during the growing season can also be used to supplement dormant sprays. Degree-days For assistance in calculating degree-days, see the Peach Twig Borer model on the UC IPM Web site at http://www.ipm.ucanr.edu/WEATHER/.



Mating Disruption Mating disruption with sex pheromones can be used to supplement dormant or bloom time sprays. The main practical use for mating disruption is postbloom treatment in organic systems where other materials are not available. Mating disruption has not been reliable against peach twig borer when used alone. It is most effective in orchards with low moth populations that are not close to other untreated peach twig borer hosts or almond orchards. Efficacy is reduced by small orchard size, uneven terrain, reduced pheromone application rates, applying too low in the tree, improper timing, and high insect pressure. Follow timing guidelines given in the treatment table below. Biological Control Peach twig borer has about 30 species of natural enemies. The gray field ant, Formica aerata, preys on peach twig borer during spring and summer. In some years these natural enemies destroy a significant portion of larvae, but by themselves they generally do not reduce twig borer populations below economically damaging levels. Other commonly found natural enemies in California are the chalcid wasps, Copidosoma (=Paralitomastix) varicornis and Hyperteles lividus, the braconid wasp Macrocentrus ancylivorus, and the grain or itch mite, Pyemotes ventricosus. Organically Acceptable Method Bloom time Bacillus thuringiensis sprays, sprays of the Entrust formulation of spinosad, and mating disruption are organically acceptable methods for peach twig borer management. Monitoring and Treatment Decisions Bloom Monitor for peach twig borer larvae and its damage during bloom (see EARLY SEASON MONITORING) when shoots are emerging, to determine if the pest is active. When emerging shoots are about 1 inch long, look for wilted leaf shoots and feeding at the base of flowers. If larvae or their damage are observed at this time, a single treatment of diflubenzuron (Dimilin), spinetoram (Delegate), spinosad (Entrust, Success), methoxyfenozide (Intrepid), or chlorantraniliprole (Altacor) can be applied or two sprays of Bt. Shoot Strike Monitoring Monitor all orchards from bloom onward for shoot strikes at the end of each generation. Shoot strikes first appear when the degree-day accumulation from moths in traps approaches 400 DD but more will be evident around 700-800 DD. Treatment threshold is three strikes per tree. (See SHOOT STRIKE MONITORING for additional information.) Pheromone Traps and Degree-day Accumulation Install pheromone traps in orchards by March 20 (see PHEROMONE TRAPS). If in-season sprays are necessary (as determined by the shoot strike sample in the previous generation), you will need results from trap catches and degree-day accumulations to time them. Once the first moth has been trapped, begin accumulating degree-days (DD) using a lower threshold of 50°F and an upper threshold of 88°F. Research has shown that best control can be achieved when treatments are applied about 400 DD from the beginning of the flight if the fruit is still green; if fruit has begun to color, however, treat at 300 DD. If Bacillus thuringiensis is used, two sprays should be applied: one at 300-350 DD and the other at 450-500 DD. If Intrepid or Altacor is used, a single application is effective and should be applied at 300 DD. Fruit Samples Examine fruit on trees every other week after color break (see PREHARVEST FRUIT SAMPLES) to detect any developing problems in the orchard and take a fruit damage sample at harvest to assess the effectiveness of the current year's IPM program and to determine the needs of next year's program, (see FRUIT EVALUATION AT HARVEST). Record results for harvest sample. (Example form available online)




UPDATED 8/15 The following are ranked with the pesticides having the greatest IPM value listed first—the most effective and least harmful to natural enemies and honey bees, and the environment are at the top of the table. When choosing a pesticide,






UPDATED 8/15 consider information relating to air and water quality, resistance management, and the pesticide's properties and application timing. Not all registered pesticides are listed. Always read the label of the product being used.

DELAYED-DORMANT A. NARROW RANGE OIL (440 or higher) 4–6 gal 1–1.5 gal 4 0 MODE OF ACTION: Contact including smothering and barrier effects. COMMENTS: Choose a narrow range oil with a 50% distillation point of 440 or higher for dormant season use. . . . PLUS . . . SPINOSAD (Entrust)# 1.25–2.5 oz 0.42–0.83 oz 4 1 (Success) 4–8 oz 1.3–2.7 oz 4 1 MODE-OF-ACTION GROUP NUMBER1: 5 COMMENTS: Apply with a narrow range oil to suppress overwintering mite and scale populations. For organic

produce, check with your certifier to determine which narrow range oils are organically acceptable. Toxic to bees; do not spray directly or allow to drift onto blooming crops or weeds where bees are foraging.

. . . or . . . DIFLUBENZURON* (Dimilin 2L) 12–16 fl oz/acre 12 0 MODE-OF-ACTION GROUP NUMBER1: 15 COMMENTS: Apply in sufficient water to ensure good coverage. Apply with narrow range oil at 1.5% oil by volume. . . . or . . . METHOXYFENOZIDE (Intrepid 2F) 8–16 oz/acre 4 7 MODE-OF-ACTION GROUP NUMBER1: 18 COMMENTS: Do not apply more than 16 fl oz/acre per application or 64 fl oz/acre per season. . . . or . . . SPINETORAM (Delegate WG) 3–7 oz/acre 4 1 MODE-OF-ACTION GROUP NUMBER1: 5 COMMENTS: Toxic to bees; do not spray directly or allow to drift onto blooming crops or weeds where bees are

foraging. . . . or . . . ESFENVALERATE* (Asana XL) Label rates 12 14 MODE-OF-ACTION GROUP NUMBER1: 3A COMMENTS: An alternative to diazinon if resistance is suspected. Use when populations of peach twig borer are

high. Use of this material during the dormant season may be detrimental to natural enemies of mites and result in mite outbreaks during the growing season. Highly toxic to bees; do not spray directly or allow to drift onto blooming crops or weeds where bees are foraging.

. . . or . . . PERMETHRIN* (Pounce) Label rates 12 14 MODE-OF-ACTION GROUP NUMBER1: 3A COMMENTS: An alternative to diazinon if resistance is suspected. Use when populations of peach twig borer are

high. Use of this material during the dormant season may be detrimental to natural enemies of mites and result in mite outbreaks during the growing season. Highly toxic to bees; do not spray directly or allow to drift onto blooming crops or weeds where bees are foraging.

BLOOM A. DIFLUBENZURON* (Dimilin 2L) 12–16 oz/acre 12 0 MODE-OF-ACTION GROUP NUMBER1: 15 COMMENTS: Include vegetable oil at the rate of 1 qt/acre. Do not apply after petal fall. Do not exceed 2 applications

in any given season. B. METHOXYFENOZIDE (Intrepid 2F) 8–16 oz/acre 4 7 MODE-OF-ACTION GROUP NUMBER1: 18






UPDATED 8/15 COMMENTS: Apply at petal fall. Do not apply more than 16 fl oz/acre per application or 64 fl oz/acre per season. C. SPINOSAD (Entrust)# 1.25–2.5 oz 0.42–0.83 oz 4 1 (Success) 4–8 fl oz 1.3–2.7 fl oz 4 1 MODE-OF-ACTION GROUP NUMBER1: 5 COMMENTS: Do not apply more than 29 oz/acre per year of Success or 9 oz/acre per year of Entrust. Most effective

when applied at petal fall. This product is toxic to bees for 3 hours following treatment; apply in late evening after bees have stopped foraging.

D. CHLORANTRANILIPROLE (Altacor) 3–4.5 oz/acre 4 10 MODE-OF-ACTION GROUP NUMBER1: 28 COMMENTS: Do not used more than 4.5 fl oz/acre per application or more than 9 fl oz/acre per season. E. SPINETORAM (Delegate WG) 3–7 oz/acre 4 1 MODE-OF-ACTION GROUP NUMBER1: 5 COMMENTS: This product is toxic to bees for 3 hours following treatment; apply in late evening after bees have

stopped foraging. F. BACILLUS THURINGIENSIS ssp. KURSTAKI# (various products) Label rates — 4 0 MODE-OF-ACTION GROUP NUMBER1: 11A COMMENTS: Treatments are timed by examining larval emergence from hibernacula. Treat when larval activity is

detected by bud feeding or emergence from hibernacula and again 7-10 days later. This usually coincides with an application at the beginning of bloom and the second 7–10 days later, often full bloom to petal fall. In years when peach twig borer emergence is extended, make the second at petal fall. Compatible with fungicide sprays and can be tank mixed with them. Good coverage is essential. Ground application using a concentrate rate (80–100 gal water maximum) is preferred. If aerial applications must be made because conditions do not permit ground application, a concentrate rate (5 gal or less) is preferred. Fly material on at a height of about 20 ft over the canopy using appropriate nozzles to allow better deposition on the treetops. Precede this treatment with an oil spray during the delayed-dormant season to control San Jose scale and European red mite eggs.

POSTBLOOM A. CHLORANTRANILIPROLE (Altacor) 3–4.5 oz/acre 4 10 MODE-OF-ACTION GROUP NUMBER1: 28 COMMENTS: Do not used more than 4.5 fl oz/acre per application or more than 9 fl oz/acre per season.






UPDATED 8/15 B. METHOXYFENOZIDE (Intrepid 2F) 8–16 oz/acre 4 7 MODE-OF-ACTION GROUP NUMBER1: 18 COMMENTS: Do not apply more than 16 fl oz/acre per application or 64 fl oz/acre per season. C. SPINETORAM (Delegate WG) 3–7 oz/acre 4 1 MODE-OF-ACTION GROUP NUMBER1: 5 COMMENTS: Toxic to bees; do not spray directly or allow to drift onto blooming crops or weeds where bees are

foraging. D. SPINOSAD (Entrust)# 1.25–2.5 oz 0.42–0.83 oz 4 1 (Success) 4–8 oz 1.3–2.7 oz 4 1 MODE-OF-ACTION GROUP NUMBER1: 5 COMMENTS: Do not apply more than 29 oz/acre per year of Success or 9 oz/acre per year of Entrust. Most effective

when applied at petal fall. Toxic to bees; do not spray directly or allow to drift onto blooming crops or weeds where bees are foraging.

E. PHOSMET (Imidan 70-W) 2 1/8–4 ¼ lb ¾–1 lb 168 (7

days) 14


are foraging. F. ESFENVALERATE* (Asana XL) 8–14.5 fl oz 3.1–5.8 fl oz 12 14 MODE-OF-ACTION GROUP NUMBER1: 3A COMMENTS: Use is not generally recommended on perennial crops in the San Joaquin Valley because high label

rates can cause outbreaks of secondary pests. While low label rates reduce the potential for secondary outbreaks in the Sacramento Valley, they should only be used where resistance to organophosphates has not become a problem and other methods such as mating disruption are not feasible. Highly toxic to bees; do not spray directly or allow to drift onto blooming crops or weeds where bees are foraging.

G. BACILLUS THURINGIENSIS ssp. KURSTAKI# (various products) Label rates — 4 0 MODE-OF-ACTION GROUP NUMBER1: 11A COMMENTS: Make two applications: one at 300-350 DD from biofix and the other at 450-500 DD. Compatible with

fungicide sprays and can be tank mixed with them. Good coverage is essential. Ground application using a concentrate rate (80–100 gal water maximum) is preferred.

H. MATING DISRUPTANTS (CheckMate PTB-XL) Label rates 0 0 (CheckMate SF) 150-200 dispensers/acre 0 0 COMMENTS: Mating disruptants have not provided reliable control when used alone. Used primarily in organic

orchards to supplement bloom sprays. Check with certifier to determine which products are organically acceptable. Place pheromone dispensers in orchards when you begin to catch the first moths in pheromone traps usually in April to May, depending on your location in the state. Apply in top one-third of canopy. Follow the manufacturer's recommendations for placement, the number of dispensers to use, and replacement intervals. Reapply the pheromones at the recommended timing for later varieties. If you are catching more than 5 moths per pheromone trap per week within one generation of harvest, however, treat with an insecticide rather than replacing dispensers. When using mating disruption, monitor the orchard regularly for shoots strikes at the end of each generation to verify that the technique is effective. Also monitor fruit from the tops of trees regularly for signs of larvae or damage; monitor more frequently during the final 4 weeks before harvest. Treat with insecticide if there are more than an average of 3 to 5 shoot strikes per tree after the first moth flight or if larvae are found in green fruit.






UPDATED 8/15







(8/15) Peachtree Borer 44 Online with photos at http://www.ipm.ucanr.edu/PMG/selectnewpest.nectarine.html

PEACHTREE BORER (8/15) Scientific Name: Synanthedon exitiosa DESCRIPTION OF THE PEST Gum exuding from around the base of the trunk is evidence of peachtree borer. Larvae of the peachtree borer, found mainly in coastal areas and in the northern San Joaquin Valley, are white with brown heads. Adults are clear-winged moths with blue-black bodies having yellow or orange bands across the abdomen. The adult peachtree borer may be found from May to September, with larvae present in the tree the rest of the year. There is only one generation each year. DAMAGE This wood-boring insect can successfully attack healthy trees. The larval stage bores into the crown and trunk of the tree and mines the cambial layer. If this occurs for several years, the tree may eventually become girdled and die. MANAGEMENT Apply insecticides when adults emerge in May and again 6 weeks later. Pheromone traps are available to monitor adult emergence. Insecticides are not likely to kill larvae within the tree but will protect against reinfestation as emerged adults lay new eggs on the trunk. Results may not be evident until the following season.




UPDATED 8/15 The following are ranked with the pesticides having the greatest IPM value listed first—the most effective and least harmful to natural enemies and honey bees, and the environment are at the top of the table. When choosing a pesticide, consider information relating to air and water quality, resistance management, and the pesticide's properties and application timing. Not all registered pesticides are listed. Always read the label of the product being used. A. ESFENVALERATE* (Asana XL) 4.8–14.5 fl oz 2–5.8 fl oz 12 14 MODE-OF-ACTION GROUP NUMBER1: 3A COMMENTS: Apply as a directed trunk and scaffold limb spray. Thorough coverage of trunk and scaffolds is

required. In dilute application, do not apply more than 200 gal water/acre at the 5.8 fl oz rate. Highly toxic to bees; do not spray directly or allow to drift onto blooming crops or weeds where bees are foraging.







(8/15) Plant Bugs 45 Online with photos at http://www.ipm.ucanr.edu/PMG/selectnewpest.nectarine.html

PLANT BUGS (8/15) Scientific Names: Lygus hesperus, Lygus elisus, and Calocoris norvegicus DESCRIPTION OF THE PESTS Adult lygus bugs are somewhat variable in color and size. In general the adults are about 0.20 to 0.25 inch long. Lygus hesperus adults vary from yellowish to reddish brown and the adults of Lygus elisus are pale or yellowish green. A distinctive yellow triangle is located in the middle of the back. Overwintering males of both species are mahogany colored, while the females are reddish. Eggs are slightly curved, elongated, flattened on one end, and inserted into plant tissue. Nymphs are pale green in color. Later instar nymphs have circular, black spots on the dorsum. Lygus bugs overwinter as adults in plant debris, in the crown of plants on the orchard floor, and in uncultivated areas outside the orchard. As temperatures rise, females begin laying eggs on a wide range of plants, especially mustards. As plants begin to dry up in uncultivated areas, lygus adults migrate to irrigated areas where mating occurs. It is believed adults are chiefly responsible for damage to fruit orchards, as nymphs are rarely found in trees. There may be as many as 6 to10 overlapping generations per year. Calocoris adults are about 0.25 inch in length with a green-colored body. The wings have a reddish brown tint and are black where they overlap. There are also two black dots on the thorax. Calocoris is usually found on mustard, wild radish, and vetch hosts and is most common in the northern San Joaquin and Sacramento valleys. Populations of Calocoris may build up on cover crops, especially purple vetch. There is only one generation a year so late season problems do not occur with this pest. Adult Calocoris can be distinguished from lygus bugs by the presence of two black dots on the back just behind the head. Calocoris nymphs do not have red-tipped antennae and black spots on the back as do lygus nymphs. Calocoris nymphs tend to be longer and narrower than lygus nymphs and have fine black hairs on the body. DAMAGE Damage to rapidly growing shoot tips can begin as early as mid-May in most years, when adult plant bugs begin laying eggs and feeding in the soft tissue at the tips of the shoots. They can also insert eggs in fruit at this time. Severely damaged terminals may resemble peach twig borer and oriental fruit moth shoot strike, but there is no tunneling in the shoot tips and damage generally occurs lower in the tree. Affected growing tips may die, causing lateral buds to push and shoots to become bushy. Plant bug feeding on green fruit may result in gumming, but gum is usually absent on nearly ripe and ripe fruit. On green fruit, feeding stings cause the outermost cortical cells of nectarine flesh to die, resulting in small, bluish green spots. The skin then develops a small, dead area that often splits as the fruit grows, frequently causing it to be misshapen. On nearly ripe fruit, feeding is characterized by small, dead areas where a small cavity has developed beneath the skin. Fruit damage is sporadic and doesn't occur every year; however, in some years severe economic losses can occur. In general, plant bug populations are highest in years where there is lots of lush vegetation growing in and around the orchard. MANAGEMENT Generally speaking, plant bug damage is worse in orchards planted near wild or uncultivated areas or in orchards near a host such as alfalfa, cotton, safflower, or tomatoes. Damage is often heavier on outside rows or in areas of the orchard that are nearest to a source of migrating adults. Anticipate migrating adults as other hosts begin to dry or are cut or harvested. Cultural Control In orchards located away from an outside plant bug source, clean cultivation or a weed-free orchard floor will aid in suppressing these pests. Where hard-to-kill broadleaf perennials are present, treat the orchard floor with an insecticide when sweep net counts indicate a potentially damaging population is present in the weeds. Where migration is a problem, destroy as many surrounding hosts as possible in early spring before first-generation nymphs complete their development. If you own or manage the adjacent fields, another alternative is to treat these areas with pesticides, although there may be hazards to foraging bees.



New orchards that are planted next to weedy areas are especially susceptible to damage from both plant bugs and thrips as the weeds dry out. If an orchard is near an alfalfa field, strip-cutting the alfalfa or leaving a strip uncut nearest to the orchard will help prevent migration out of the alfalfa. Organically Acceptable Methods Cultural controls are organically acceptable methods for controlling these pests. Monitoring and Treatment Decisions Plant bugs may be present in the orchard, but they may not move up to feed on fruit in trees, so monitoring only indicates whether they are present in the orchard and not whether a treatment needs to be applied. Use a sweep net to detect the presence of bugs in the orchard. Orchards with ground covers are likely to harbor plant bug populations. If plant bugs are present, cultivate or mow closely before green fruit are present. Examine fruit on trees every other week after color break (see PREHARVEST FRUIT SAMPLES) to detect any developing problems in the orchard and take a fruit damage sample at harvest to assess the effectiveness of the current year's IPM program and to determine the needs of next year's program (see FRUIT EVALUATION AT HARVEST). Record results for harvest sample. (Example form available online)




UPDATED 8/15 The following are ranked with the pesticides having the greatest IPM value listed first—the most effective and least harmful to natural enemies and honey bees, and the environment are at the top of the table. When choosing a pesticide, consider information relating to air and water quality, resistance management, and the pesticide's properties and application timing. Not all registered pesticides are listed. Always read the label of the product being used. A. ESFENVALERATE* (Asana XL) 4.8–14.5 fl oz 2–5.8 fl oz 12 14 MODE-OF-ACTION GROUP NUMBER1: 3A COMMENTS: The use of esfenvalerate is not generally recommended on perennial crops in the San Joaquin Valley

because high label rates can cause outbreaks of secondary pests. While low label rates reduce the potential for secondary outbreaks in the Sacramento Valley, they should only be used where resistance to organophosphates has not become a problem and other methods such as mating disruption are not feasible. Highly toxic to bees; do not spray directly or allow to drift onto blooming crops or weeds where bees are foraging.

B. BETA-CYFLUTHRIN+IMIDACLOPRID* (Leverage 360) 2.4–2.8 fl oz 12 7 MODE-OF-ACTION GROUP NUMBER1: 3A + 4A COMMENTS: Use allowed under a Supplemental Label. Highly toxic to bees; do not spray directly or allow to drift onto

blooming crops or weeds where bees are foraging. C. PHOSMET (Imidan 70-W) 2 1/8–4 ¼ lb ¾–1 lb per 168 (7

days) 14


are foraging. E. INDOXACARB (Avaunt) 6 oz/acre 12 14 MODE-OF-ACTION GROUP NUMBER1: 22A COMMENTS: Also controls katydids and Oriental fruit moth. Do not apply in more than 200 gal water/acre. Highly

toxic to bees; do not spray directly or allow to drift onto blooming crops or weeds where bees are foraging. F. IMIDACLOPRID (Admire Pro) 1.4–2.8 fl oz 12 0 MODE-OF-ACTION GROUP NUMBER1: 4A COMMENTS: Highly toxic to bees; do not spray directly or allow to drift onto blooming crops or weeds where bees are foraging. G. METHOMYL* (Lannate LV) 3 pt 0.75 pt 3 days 1 MODE-OF-ACTION GROUP NUMBER1: 1A






UPDATED 8/15 ** For dilute applications, rate is per 100 gal water to be applied in 300-500 gal water/acre, according to label; for concentrate

applications, use 80-100 gal water/acre, or lower if label allows. * Permit required from county agricultural commissioner for purchase or use. ‡ Restricted entry interval (REI) is the number of hours (unless otherwise noted) from treatment until the treated area can be




(8/15) Prune Limb Borer and American Plum Borer 48 Online with photos at http://www.ipm.ucanr.edu/PMG/selectnewpest.nectarine.html

PRUNE LIMB BORER and AMERICAN PLUM BORER (8/15) Scientific Names: Prune limb borer: Bondia comonana American plum borer: Euzophera semifuneralis DESCRIPTION OF THE PESTS Prune limb borer and American plum borer are sporadic pests in young stone fruit orchards from Tehama County to Kern County. Young larvae are white with a large, dark brown head; when mature, larvae are about 1 inch long with a dull white or pinkish body. The larva overwinters in a cocoon within the tree. Adult moths emerge in April and May. Females lay eggs on callus tissue near pruning wounds, in scaffold crotches of young trees, near graft unions, or on crown galls. The forewings of the moth are gray with brown and black marks and have a wingspan of about 0.75 inch. DAMAGE Larvae bore into the tree leaving reddish orange frass and gum pockets. The boring is most damaging to the scaffold crotches or graft unions of young trees. Vigorous trees will heal over, but with heavy, prolonged infestations, scaffolds may break with wind or a heavy crop. MANAGEMENT Monitor young orchards in spring and summer for frass and gum pockets, which tend to be very visible if present. If larvae are present, spray trees from 1 foot above the scaffold crotch to 1 foot below, two to three times during the growing season. Make the first application from mid- to late April and subsequent applications at 6-week intervals.


Amount to use REI‡ (hours)

PHI‡ (days)

UPDATED 8/15 The following are ranked with the pesticides having the greatest IPM value listed first—the most effective and least harmful to natural enemies and honey bees, and the environment are at the top of the table. When choosing a pesticide, consider information relating to air and water quality, resistance management, and the pesticide's properties and application timing. Not all registered pesticides are listed. Always read the label of the product being used. A. CARBARYL* (Sevin XLR Plus) 3–4 qt/acre 12 1 MODE-OF-ACTION GROUP NUMBER1: 1A COMMENTS: Use a hand-held sprayer. Do not apply more than 14 qt/acre per season. Highly toxic to bees; do not

spray directly or allow to drift onto blooming crops or weeds where bees are foraging. B. DIAZINON* (Diazinon 50WP) 0.21 lb/gal water 5 days 21 MODE-OF-ACTION GROUP NUMBER1: 1B COMMENTS: For in-season use only. Use a hand-held sprayer. Apply 1 pint per tree; do not apply more than 4 lb

product/acre per application.Highlytoxictobees;donotspraydirectlyorallowtodriftontobloomingcropsorweedswherebeesareforaging.


* Permit required from county agricultural commissioner for purchase or use. 1 Rotate chemicals with a different mode-of-action Group number, and do not use products with the same mode-of-action



(8/15) San Jose Scale 49 Online with photos at http://www.ipm.ucanr.edu/PMG/selectnewpest.nectarine.html

SAN JOSE SCALE (8/15) Scientific Name: Diaspidiotus (= Quadraspidiotus) perniciosus DESCRIPTION OF THE PEST Female San Jose scale lay eggs that hatch immediately and the young emerge from under the edge of the adult scale covering. These tiny, yellow crawlers wander in a random fashion until they find a suitable place to settle. Immediately upon settling, the crawlers insert their mouthparts into the host plant and begin feeding and secreting a white, waxy material (white cap stage); eventually the waxy covering turns black (black cap stage). San Jose scales overwinter predominantly (80%) in the black cap stage, although in mild years some adult females may also survive. In late January, nymphs resume their growth, molting two or three times before becoming adults in March. Immature male and female scales are indistinguishable until after the first molt when the body of the male begins to elongate. Males molt a total of four times after which yellowish, winged adult males emerge to mate with females. The adult female San Jose scale remains under its shell, which is gray and circular; the body under the shell covering is yellow. After mating, females produce eggs, which remain within the female body and hatch there. The crawlers emerge from the female. Crawlers from the overwintering females begin hatching in April, with their peak emergence usually in early May. There are usually four to five generations per year. Crawlers may be present throughout the summer and fall. DAMAGE San Jose scales cause injury by feeding on twigs, branches, and fruit; they may also inject salivary toxins while feeding. Heavy populations on the bark can cause gumming and kill twigs, branches, and entire trees if left uncontrolled. A characteristic, red halo like discoloration often forms around the insect on small twigs or infested fruit. Fruit with haloes will be culled because of its unsightly appearance. MANAGEMENT San Jose scale has many natural enemies that can frequently keep the pest under control if not disrupted by application of broad-spectrum insecticides. Many orchards that have not used broad-spectrum sprays for 2 or 3 years do not have San Jose scale problems. The best time to spray is during the dormant season when low-to-moderate populations can be managed with oil sprays, which don't destroy the scale parasites. The scale is monitored as part of the shoot sample during the dormant season and with pheromone traps in spring. Degree-days For assistance in calculating degree-days, see the San Jose Scale model on the UC IPM Web site at http://www.ipm.ucanr.edu/WEATHER/. Biological Control Natural enemies that feed on San Jose scale include two predaceous beetles: the twicestabbed lady beetle, Chilocorus orbus, and another small beetle Cybocephalus californicus. A number of small chalcid and aphelinid wasps, including Aphytis spp. and Encarsia (Prospaltella) sp., parasitize this scale. These predators and parasites are helpful in reducing scale populations, but broad-spectrum insecticides used during the growing season for other pests disrupt this natural control, and scale populations can build as a result. Low winter mortality due to mild temperatures will also permit a buildup of scale populations. Organically Acceptable Methods Biological control and a properly applied oil spray during the delayed-dormant period are organically acceptable management practices for this pest. Monitoring and Treatment Decisions in the Dormant Season Monitor San Jose scale during the dormant season by collecting shoots and examining them for live scale and for tiny emergence holes that indicate parasite activity. For details on dormant shoot sampling and treatment thresholds (see DORMANT SHOOT SAMPLING) and record results on a monitoring form (available online).



Because of the damage potential of this pest, annual oil sprays during the dormant or delayed-dormant period are recommended in most areas. For large-scale populations, a properly applied dormant spray with good coverage is the most effective timing and will eliminate the spring flight and suppress the infestation throughout the growing season. The following table gives a guideline for making treatment choices based on levels of infestation on dormant shoot samples: DORMANT TREATMENT DECISION TABLE (% infested shoots)

Treatment threshold Treatment Harvested before June 15 Harvested after June 15

below 20% below 5% no treatment 20-60% 5-10% oil at 6 gal/acre

over 60% over 10% oil at 2-6 gal/acre

plus insect growth regulator1

1 Using oil at the 4–6 gal rate will help prevent development of resistance to the IGR. If oil is used at the 2 gal rate, do not use the IGR in consecutive years to prevent resistance development.

Oil alone can be effective in controlling low-to-moderate populations (apply before the third week of January). If populations are high, include an insect growth regulator (pyriproxyfen-Esteem, Seize; buprofezin-Centaur) with the oil. Organophosphates are available but are associated with environmental problems and should be avoided. When the dormant organophosphate and oil spray is first omitted, San Jose scale populations may increase the first year but by the second and third year parasite populations have increased to levels where they reduce San Jose scale populations and maintain them at low levels. If you notice parasitized scale in your dormant sample, be sure to only use an insect growth regulator during the growing season. Monitoring and Treatment Decisions in the Growing Season • Monitoring with pheromone traps from late bloom until petal fall will help you keep track of the appearance

and development of scale populations as well as the level of parasitism (Aphytis and Encarsia) but does not tell you if treatment is needed.

• Need for treatment is better assessed during the dormant season and delayed-dormant sprays are the preferred timing for treatment.

• If inadequate control is achieved with the dormant spray or the dormant spray is not applied, treatment is also effective when applied soon after the emergence of crawlers in May.

• Late season sprays to control San Jose scale are not recommended. Monitoring With Traps Monitor scales by putting up pheromone traps around February 25 (see PHEROMONE TRAPS) and placing sticky tape in the trees in April. Place pheromone traps well within the canopy to keep them out of the wind. San Jose scale pheromone traps also attract both male San Jose scale and scale parasites (Aphytis melinus and Encarsia perniciosi). Adult male scale can be distinguished from parasites by the presence of a dark line across their thorax where the wings attach. (View photos of San Jose scale and parasites online) Degree-day Accumulation When the traps begin to catch males consistently, start accumulating degree-days using a 51°F lower threshold and a 90°F upper threshold. If it is needed, apply a treatment for crawlers 600 to 700 DD after you catch the first males. Confirm the presence of crawlers by checking sticky tape traps. Be aware that the traps may fail to catch any adults if weather is cold, rainy, or windy. Total generation time for San Jose scale is 1,050 DD. May Sprays If May sprays are required, use a high-volume (dilute) application at 400 gallons or more per acre for best coverage; do not use a low-volume application. Fruit Samples Examine fruit on trees every other week after color break (see PREHARVEST FRUIT SAMPLES) to detect any developing problems in the orchard and take a fruit damage sample at harvest to assess the effectiveness of the current year's IPM program and to determine the needs of next year's program (see FRUIT EVALUATION AT HARVEST). Record results for harvest sample. (Example form available online)






UPDATED 8/15 The following are ranked with the pesticides having the greatest IPM value listed first—the most effective and least harmful to natural enemies and honey bees, and the environment are at the top of the table. When choosing a pesticide, consider information relating to air and water quality, resistance management, and the pesticide's properties and application timing. Not all registered pesticides are listed. Always read the label of the product being used. If San Jose scale is a problem in the orchard, use a high-volume (dilute) application at 400 gallons or more per acre for best coverage.

DORMANT A. NARROW RANGE OIL# (440 or higher) — 1.5 gal 12 0 MODE OF ACTION: Contact including smothering and barrier effects. COMMENTS: Apply in a dilute application, using a total of 6–8 gallons of oil/acre. Choose a narrow range oil

with a 50% distillation point of 440 or higher for dormant season use. Always check with your certifier as to which oils are organically acceptable. Provides about 80% control; use for light to moderate infestations. Apply before late January when most of the scales are in black cap stage. An option for orchards where bloom sprays of Bacillus thuringiensis or other selective larvicide are planned for control of caterpillars and no broad-spectrum pesticides are used in the orchard, thus allowing beneficials to keep scale at low levels.

DELAYED-DORMANT A. NARROW RANGE OIL (440 or higher) 3–6 gal 0.5–1.5 gal 4 0 MODE OFACTION: Contact including smothering and barrier effects. COMMENTS: Choose a narrow range oil with a 50% distillation point of 440 or higher for dormant season use.

Using oil at the higher rates (4-6 gal/acre) will help prevent the development of resistance to the IGRs. If oil is used at the 2 gal/acre rate, do not use IGRs in consecutive years to prevent resistance development.

. . . PLUS . . . PYRIPROXYFEN (Seize 35WP) 4–5 oz/acre 12 14 MODE-OF-ACTION GROUP NUMBER1: 7C COMMENTS: An insect growth regulator that targets egg hatch. Good coverage is essential for good control. Do

not apply more than three applications per growing season. Use allowed under a supplemental label. . . . or . . . BUPROFEZIN (Centaur) 34.5 oz/acre 12 14 MODE-OF-ACTION GROUP NUMBER1: 16 COMMENTS: An insect growth regulator that is effective against nymphal stages. Good coverage is essential. Do

not apply more than 69 oz/acre per year.

SPRING A. PYRIPROXYFEN (Seize 35WP) 4–5 oz/acre 12 14 MODE-OF-ACTION GROUP NUMBER1: 7C COMMENTS: An insect growth regulator; apply when scale crawlers first emerge. Do not apply more than three

applications per growing season closer than 14 days apart. Good coverage is essential for good control. B. BUPROFEZIN (Centaur) 34.5 oz/acre 12 14 MODEOF-ACTION GROUP NUMBER1: 16 COMMENTS: An insect growth regulator that is effective against nymphal stages. Good coverage is essential. Do

not apply more than 69 oz/acre per year.






UPDATED 8/15 C. DIAZINON* (Diazinon 50W) 3–4 lb 1 lb 5 days 21 MODE-OF-ACTION GROUP NUMBER1: 1B COMMENTS: Not allowable for use by many canneries. Avoid drift and tailwater runoff into surface waters.

Where nectarines are grown adjacent to waterways, do not use this material. Apply with oil to reduce the risk of resistance development.

D. CARBARYL* (Sevin XLR Plus) 3–4 qt/acre 12 1 MODE-OF-ACTION GROUP NUMBER1: 1A COMMENTS: Will cause mite outbreaks. Not recommended for routine use, especially early in the season.

Apply with oil. Highly toxic to bees; do not spray directly or allow to drift onto blooming crops or weeds where bees are foraging.


* Permit required from county agricultural commissioner for purchase or use. ‡ Restricted entry interval (REI) is the number of hours (unless otherwise noted) from treatment until the treated area can

be safely entered without protective clothing. Preharvest interval (PHI) is the number of days from treatment to harvest. In some cases the REI exceeds the PHI The longer of two intervals is the minimum time that must elapse before harvest.




(8/15) Shothole Borer 53 Online with photos at http://www.ipm.ucanr.edu/PMG/selectnewpest.nectarine.html

SHOTHOLE BORER (8/15) Scientific Name: Scolytus rugulosus DESCRIPTION OF THE PEST Shothole borers are tiny brown or black beetles; their white legless grubs mine the tree's cambium layer (sapwood). Adult females bore tiny holes in the bark and lay eggs in the cambium layer of the tree. When the eggs hatch, young larvae feed and excavate secondary galleries at right angles to the egg gallery. The outline of the gallery system resembles a centipede. There are from one to three generations each year. DAMAGE Normally a number of shothole borer adults invade a tree at the same time. Healthy trees exude resin, which usually kills the insects. If the tree has injured or weakened areas, this resin buildup does not develop and the invasion is successful. Ultimately larvae can girdle the tree, causing tree or branch death. MANAGEMENT Maintaining healthy trees and preventing sunburn are the keys to preventing damage by shothole borer. Painting the trees with white wash or a 50:50 mixture of white interior latex paint and water will help prevent sunburn and possibly inhibit egg laying. Avoid pruning during summer, and prune trees so that scaffolds are shaded to prevent sunburn. Remove horizontal scaffolds when pruning/thinning young trees. Protect newly planted or newly grafted trees from sunburn by painting the trunk and graft with white interior latex paint or using tree wrappers around the trunk. If paint is used, be sure to mix it with water; undiluted latex paint can kill young trees. Thin the latex paint to a mixture of one-half water and one-half latex paint and paint the trunk from 2 inches below ground level to 2 feet above. Prune to eliminate areas in older trees infested with shothole borer. Remove severely infested trees. Burn or remove all infested wood from the orchard before the growing season starts. Do not leave pruned limbs or stumps (healthy or infested) near orchards (for example, in woodpiles) as populations can emerge from these materials before they dry out, and beetles will then migrate into orchards. There are no insecticide treatments recommended for this insect.


Amount to use

UPDATED 8/15 A. WHITE LATEX PAINT# 50% paint and water mixture COMMENTS: Paint trees at time of planting. Be sure paint extends below ground level. This treatment will prevent

sunburn, which can reduce attack by shothole borer.

# Acceptable for use on organically grown produce.


(8/15) Stink Bugs 54 Online with photos at http://www.ipm.ucanr.edu/PMG/selectnewpest.nectarine.html

STINK BUGS (8/15) Scientific Names: Redshouldered stink bug: Thyanta pallidovirens Uhler's stink bug Chlorochroa uhleri Green stink bug: Acrosternum hilare Consperse stink bug: Euschistus conspersus Say's stink bug: Chlorochroa sayi DESCRIPTION OF THE PESTS Several kinds of stink bugs feed in nectarine orchards, but they are not pests in every orchard every year. Outbreaks appear to be cyclical. The different species of stink bugs all have similar life histories. They overwinter as adults under leaves and trash, in the crowns of plants, and in clumps of grass on the orchard floor. They also may be found outside the orchard in the crowns of plants such as blackberry or in other protected places such as box piles and buildings. After mating, if suitable host plants are not present in the orchard, adults move out of the orchard to suitable host plants. Most of the species remain on weeds and ground cover plants at this time, but the green stink bug may move into the trees. Adults have shield-shaped bodies that are about 0.5 inch long and either brown or green with red, pink, or yellow markings. Barrel-shaped eggs are laid in clusters of about 14 on leaves of broadleaf plants. Eggs are pearly white when first laid, later turning cream colored or pinkish just before hatching. For consperse stink bugs, a row of spines encircle the top of the eggs; the other species have concentric black rings on top of the eggs. Early nymphal stages have various markings and patterns and no wings but resemble adults in shape. Nymphs develop prominent wing pads in the fourth and fifth instars. In early June, adults may migrate to trees where they deposit eggs on the foliage. Adults from this generation also feed on developing fruit. Second-generation adults begin appearing in late July-August and can cause severe damage to unharvested fruit. Second-generation adults feed until the onset of cool weather when they migrate back to protected sites or overwintering hosts. The rough shield bug, Brochymena sulcata, is a beneficial insect and should not be confused with harmful stink bug species. This stink bug is common in Central Valley orchards; adults are 0.5 to 0.66 inches long, brownish or gray, with a very rough and angular shape. Both nymphs and adults feed on caterpillars and other insects. DAMAGE Stink bugs insert their needlelike mouthparts into fruit and feed on plant juices. Initially the feeding sites are small, translucent, blue-green spots. Damaged flesh under the skin later turns into gray or whitish pithy areas. Gum may exude from feeding areas on green nectarines. Because frost damage can also cause the nectarine to exude gum, examine the flesh of the fruit for needlelike stains caused by stink bug feeding. Damaged areas will fail to grow, and fruit attacked early in the season develops irregular, depressed areas or dimples. On nearly ripe fruit, exterior symptoms resemble a bruise and if the fruit is peeled, white corky or pithy areas will be found. One bug may feed on many fruit, thus a rather low population can cause severe damage. On nectarines, the damage resembles that caused by rust; look for the presence of stink bugs to confirm the cause of the damage. MANAGEMENT Focus your stink bug management program on keeping damaging populations from moving into the fruit trees. Monitor the orchard in spring to detect their presence. Monitoring and Treatment Decisions Using a sweep net, begin monitoring after the weather has warmed up in March and look for overwintering bugs feeding on curly dock, common mullein, Russian thistle (especially the base of the plant), or other broad-leaved plants. Sample the orchard and adjacent weedy areas. If bugs are found, apply spot treatments to kill adults before they can move to other locations. Orchards with ground covers are likely to harbor stink bug populations. If stink bugs are present, cultivate or mow closely before green fruit appear. Monitor fruit beginning in early June every other week. Adult bugs often hide on the opposite side of the limb as they are approached, making them difficult to see. Look for sappy exudate on fruit, blue-green spots, or gum that


(8/15) Stink Bugs 55 Online with photos at http://www.ipm.ucanr.edu/PMG/selectnewpest.nectarine.html

may exude from feeding sites. Some fruit should also be peeled to detect the presence of white pithy or corky areas, or the trees can be sampled with a beating tray. Double cone traps that are baited with an aggregation pheromone are also available for monitoring the consperse stink bug but will not attract other species of stink bugs. Place these traps in tree crotches near the orchard's border to detect the presence of adult consperse stink bugs. Consider treating if damaged fruit is common or if adult bugs are seen. Apply a full coverage spray to trees in affected areas of the orchard. Clean cultivation of orchards in fall will discourage overwintering bugs. Examine fruit on trees every week after color break (see PREHARVEST FRUIT SAMPLES) to detect any developing problems in the orchard, and take a fruit damage sample at harvest to assess the effectiveness of the current year's IPM program and to determine the needs of next year's program (see FRUIT EVALUATION AT HARVEST). Record results for harvest sample. (Example form available online)




UPDATED 8/15 The following are ranked with the pesticides having the greatest IPM value listed first—the most effective and least harmful to natural enemies and honey bees, and the environment are at the top of the table. When choosing a pesticide, consider information relating to air and water quality, resistance management, and the pesticide's properties and application timing. Not all registered pesticides are listed. Always read the label of the product being used. A. INDOXACARB (Avaunt) 6 oz/acre 12 14 MODE-OF-ACTION GROUP NUMBER1: 22A COMMENTS: Also controls katydids and Oriental fruit moth. Do not apply in more than 200 gal/acre. Highly toxic

to bees; do not spray directly or allow to drift onto blooming crops or weeds where bees are foraging. B. CARBARYL* (Sevin XLR Plus) 3–4 qt/acre 12 1 MODE OF ACTION GROUP NUMBER1: 1A COMMENTS: May cause increased spider mite problems; best used late in the season. Do not apply more than 14

qt/acre per season. Highly toxic to bees; do not spray directly or allow to drift onto blooming crops or weeds where bees are foraging.

C. ESFENVALERATE* (Asana XL) 4.8–14.5 fl oz 2–5.8 fl oz 12 14 MODE-OF-ACTION GROUP NUMBER1: 3A COMMENTS: Based on research in California pistachio orchards, this material effectively controls stink bugs. For

dilute applications, do not apply in more than 200 gal water/acre at the 5.8 oz rate. Highly toxic to bees; do not spray directly or allow to drift onto blooming crops or weeds where bees are foraging.






(8/15) Webspinning Spider Mites 56 Online with photos at http://www.ipm.ucanr.edu/PMG/selectnewpest.nectarine.html

WEBSPINNING SPIDER MITES (8/15) Scientific Names: Twospotted spider mite: Tetranychus urticae Pacific spider mite: Tetranychus pacificus DESCRIPTION OF THE PESTS Pacific and twospotted spider mites overwinter as adult females in protected places on the tree or in the litter, trash, and weeds on the orchard floor. The overwintering forms of both species are reddish orange. The mites become active in early spring soon after trees leaf out and begin feeding on weeds or in the lower part of the trees. Both species are favored by hot, dry conditions, and as the weather becomes warmer, they increase in numbers and move up the center of the tree until the entire tree is infested. Adult females are about 0.03 inch long. Active summer females are greenish or pale yellow with large dark spots on each side of the body. The Pacific mite may also have a second pair of spots near the posterior end of the body, which help distinguish it from the twospotted mite. Females can complete a generation in as little as 10 days during the hot part of summer. Eggs are spherical and almost translucent when first laid. They are generally deposited on the underside of leaves. As heavy populations build up, eggs may be deposited on both surfaces. There may be from 8 to 18 generations per year depending on temperature. DAMAGE Stone fruits can tolerate some mite damage, particularly on water sprouts in the center of trees. Twospotted mites generally feed on the lower leaf surface, but Pacific mites may be found on both leaf surfaces. Feeding by both species causes a mottling of the leaves, and under severe conditions, can cause heavy leaf drop. Both species produce heavy webbing. If defoliation happens early in the season, fruit fails to size properly, and limbs and fruit may be exposed to sunburn. MANAGEMENT Successful mite management requires regular monitoring both for pest mites and predators as well as good cultural practices to maintain healthy trees that are not stressed for water. In many orchards with adequate predator populations, no treatments for spider mites are necessary. It is especially important to monitor mites, however, in orchards where insecticides (e.g. pyrethroids, organophosphates, and carbamates) that destroy mite predators are used during the growing season. In all orchards, use timed searches from May through August to assess the need for treatment. Biological Control Predators are very important in regulating pest mite populations in orchards. The most dependable predator is the western predatory mite, Galendromus occidentalis. This mite is about the same size as a spider mite and is generally translucent, but may be shaded in various colors of red to brown, depending on its food source. Galendromus occidentalis is pear shaped, somewhat shiny, and generally moves faster than plant-feeding mites. Under optimum conditions, this predator can produce a generation in 7 days, which allows it to build up rapidly and in many cases control plant-feeding mites. Sixspotted thrips, Scolothrips sexmaculatus, are often responsible for the sudden disappearance of Pacific and twospotted mite populations. Adult sixspotted thrips are tiny, brownish, slender insects characterized by three dark spots on each forewing. Both the adults and small yellowish larvae are predaceous on mites. If sixspotted thrips are present on most mite-infested leaves, a treatment is rarely needed. The spider mite destroyer, Stethorus picipes, is a small lady beetle that feeds on spider mites. Adults are about the size of a pinhead, jet black, with inconspicuous silver hairs covering the body. The hairs can be seen with a hand lens. The elongated larvae are small, dull black, and covered with numerous hairs, giving them a velvety appearance. Plant-feeding mite populations sometimes increase to damaging levels before Stethorus brings the populations under control; however, they are voracious feeders and can control populations quickly once they become abundant. The above predators are adversely affected by certain materials applied for control of other pests such as oriental fruit moth and thrips. Every effort should be made to use pesticides that have the least adverse effect on these predators.



Cultural Control Management of twospotted and Pacific mites depends on a number of factors. Mite buildups are encouraged by hot, dry, and dusty conditions, so keep orchards well irrigated, and treat orchard roads, if necessary, to keep dust to a minimum. Proper pruning and adequate amounts of fertilizer to maintain tree vigor will also discourage twospotted and Pacific mites. Organically Acceptable Methods Biological controls, including predator releases, and cultural controls and various types of oil sprays are organically acceptable management tools. Monitoring and Treatment Decisions From May through August, monitor for mites at least weekly. If the orchard has problem areas such as trees along roads or water-stressed trees, monitor every few days. Before July 1, focus monitoring on hot spots—i.e., areas that develop mites first; these are often dusty or water stressed areas of the orchard. Once the treatment threshold has been reached in these areas, sample the remainder of the orchard to determine if a spot treatment is sufficient or the entire orchard requires treatment. After July 1, monitor the whole orchard, dividing it into sampling areas that could be treated separately. Populations begin to decline after August 15, and treatments are generally not needed after this point. How to Monitor:

1. In each orchard up to 40 acres, conduct a 5-minute search in two separate areas of the orchard, for a total sampling time of 10 minutes.

2. For each 5-minute search, examine at least 2 to 3 leaves on 10 trees. Note presence or absence of spider mites or predators. Sample leaves from both inside and outside the tree.

3. If mite population is spotty, continue to do two 5-minute searches throughout the summer. If you determine the mite population is consistent throughout orchard, one 5-minute search is adequate.

4. Keep records of sample results on the monitoring form on the online version of this publication. 5. Use the guidelines below to determine need for treatment.

Mite Ratings (percent of leaves with one or more mites): • low (1-20%) = an occasional mite on occasional leaf; hard to find. • low to moderate (21-39%) = mites easier to find but no colonies or webbing and few eggs. • moderate (40-60%) = some leaves without mites, other leaves with small colonies; eggs easy to find but very

little webbing. • moderate to high (61-79%) = mites on most leaves, colonies with eggs, and webbing on some leaves. • high (80-100%) = lots of mites on most leaves; eggs and webbing abundant.

Predator Ratings: • low = hard to find; less than one predator per six leaves (only a few leaves will have predators). • moderate = easier to find; one predator per three leaves (about half the leaves will have predators). • high = one or more predators per leaf (most leaves will have predators).

Treatment Decisions (Treat if the rating from at least one 5-minute search indicates): • low to moderate mite rating with low to moderate predator rating, or • moderate to high mite rating with moderate to high predator rating






UPDATED 8/15 The following are ranked with the pesticides having the greatest IPM value listed first—the most effective and least harmful to natural enemies and honey bees, and the environment are at the top of the table. When choosing a pesticide, consider information relating to air and water quality, resistance management, and the pesticide's properties and application timing. Not all registered pesticides are listed. Always read the label of the product being used. A. BIFENAZATE (Acramite 50WS) 0.75–1 lb/acre 12 3 MODE-OF-ACTION GROUP NUMBER1: un COMMENTS: Relatively safe for beneficial predaceous mites. Apply with ground equipment. Requires complete


B. SPIRODICLOFEN (Envidor 2SC) 16–18 fl oz/acre 12 7 MODE-OF-ACTION GROUP NUMBER1: 23 COMMENTS: Relatively safe for beneficial predaceous mites. Apply with ground equipment. Requires complete

coverage of both leaf surfaces for effective control. C. ABAMECTIN* (Agri-Mek SC) 2.25–4.25 fl oz 0.5–1 fl oz 12 21 MODE-OF-ACTION GROUP NUMBER1: 6 COMMENTS: May be combined with oil. Do not make more than 2 applications per growing season and allow at


D. NARROW RANGE OIL# (Superior, Supreme) 4 gal 1–1.5 gal See label 0 MODE-OF-ACTION: Contact including smothering and barrier effects. COMMENTS: Always check with your certifier to determine which narrow range oils are organically acceptable. E. CLOFENTEZINE (Apollo SC) 2–8 oz/acre 12 10 MODE-OF-ACTION GROUP NUMBER1: 10A COMMENTS: This material is more effective in the early part of the year; apply after sampling indicates pest mites

are increasing but before significant damage or webbing is present. Use low rate (below 4 oz) only when predators are present. Kills eggs and young larval stages. Good coverage is a must; use a minimum of 50 gal water/acre for concentrate and a maximum of 400 gal water/acre for dilute. To delay development of resistance, use only once per season.

F. HEXYTHIAZOX (Onager) 12–24 oz 3–6 oz 12 7 (Savey 50DF) 3–6 oz 0.75–1.5 oz 12 28 MODE-OF-ACTION GROUP NUMBER1: 10A COMMENTS: Apply after bloom but before adult mite buildup. Controls eggs and immatures that are sprayed or


G. FENBUTATIN OXIDE* (Vendex 50WP) 1–2 lb/acre 48 14 MODE-OF-ACTION GROUP NUMBER1: 12B COMMENTS: Don't mix with materials other than oil. Control has been variable with this product. H. PYRIDABEN (Nexter) 8.8–10.67 oz/acre 12 7 MODE-OF-ACTION GROUP NUMBER1: 21A COMMENTS: This is not as selective as other miticides, so it is best not to use it for early season control. Highly toxic

to bees; do not spray directly or allow to drift onto blooming crops or weeds where bees are foraging. I. GALENDROMUS OCCIDENTALIS# COMMENTS: Predatory mites can be released to establish or to augment resident populations. If an acaricide is

needed and predators are present, be sure to use a selective material. Useful to help reduce pest mite populations.






UPDATED 8/15







(8/15) Western Flower Thrips 60 Online with photos at http://www.ipm.ucanr.edu/PMG/selectnewpest.nectarine.html

WESTERN FLOWER THRIPS (8/15) Scientific Name: Frankliniella occidentalis DESCRIPTION OF THE PEST Western flower thrips adults are minute insects, about 0.03 inch long, with two pairs of fringed wings. The adult has three color forms that vary in abundance depending on the time of year. There is a pale form that is white and yellow, except for slight brown spots or blemishes on the top of the abdomen; an intermediate color form with an orange thorax and brown abdomen; and a dark form that is dark brown. The intermediate form is present throughout the year, but in spring the dark form predominates while the pale form is most abundant at other times throughout the year. First-instar nymphs are opaque or light yellow, turning to golden yellow after the first molt. The nymphal stage lasts from 5 to 20 days. DAMAGE Nymphs hatch and feed in numbers on tiny fruit, often under the drying calyx or flower parts. Their feeding scars the surface of the fruit. These scars enlarge as the fruit grows, and may cause fruit deformity. Thrips can also cause silvering just before nectarine fruits mature. Although some feeding does take place on blossoms, little damage results until fruit forms. Thrips can damage terminal shoots and cause them to stop growing. Usually one to two small dead leaves cling to the terminal. Buds just below the terminal grow, giving the branch a bushy appearance. MANAGEMENT Western flower thrips over winter as adults in weeds, grasses, alfalfa, and other hosts, either in the orchard floor or nearby. In early spring, if overwintering sites are disturbed or dry up, thrips migrate to flowering trees and plants and deposit eggs in the tender portions of the host plant (e.g. shoots, buds, and flower parts). Cultural Control Thrips are often attracted to weeds blooming on the orchard floor. To prevent driving thrips into the trees, do not disc the cover crop when trees are in bloom. Open, weedy land adjacent to orchards should be disced as early as possible to prevent thrips development and migration of adults into orchards. Organically Acceptable Methods Cultural controls, clean cultivation, and sprays of the Entrust formulation of spinosad are organically acceptable tools. Monitoring and Treatment Decisions Begin monitoring thrips as individual blocks begin to bloom (see EARLY SEASON MONITORING). Monitor for thrips by examining blossoms from trees by slapping a shoot with five to ten blossoms against a yellow card or look for the immature stages within the blossoms. Often nymphs are not dislodged by the slapping method so also dissect individual flowers and examine them with a hand lens for nymphs. First instar nymphs are white in color and often difficult to see, so be sure to check carefully. Check a minimum of 50 trees per orchard for nymphs. In warm springs, adults will often migrate in and out of a block without being detected so it is important to always sample for nymphs. If two or more adult thrips are present or if any nymphs are found, a treatment is warranted. If a treatment is applied, make it before the calyx becomes tight around the developing ovary. If nymphs are found under the jacket after it tightens around the fruit, use methomyl. Highly colored varieties can be damaged by thrips feeding just before harvest. Monitor orchards 2 to 3 weeks before harvest when fruit begins to color (see PREHARVEST FRUIT SAMPLES). If fruit starts showing damage, a treatment is necessary.


(8/15) Western Flower Thrips 61 Online with photos at http://www.ipm.ucanr.edu/PMG/selectnewpest.nectarine.html

Sample fruit at harvest (FRUIT EVALUATION AT HARVEST) to assess the effectiveness of the current year's IPM program and to determine the needs of next year's program. Record results for harvest sample. (Example form available online)




UPDATED 8/15 The following are ranked with the pesticides having the greatest IPM value listed first—the most effective and least harmful to natural enemies and honey bees, and the environment are at the top of the table. When choosing a pesticide, consider information relating to air and water quality, resistance management, and the pesticide's properties and application timing. Not all registered pesticides are listed. Always read the label of the product being used. A. SPINOSAD (Entrust)# 1.25–2.5 oz 0.42–0.83 oz 4 1 (Success) 4–8 oz 1.3–2.7 oz 4 1 MODE-OF-ACTION GROUP NUMBER1: 5 COMMENTS: Do not apply more than 29 oz/acre per year of Success or 9 oz/acre per year of Entrust. To avoid

development of insect resistance, do not treat successive generations of the same pest with the same product. Control may be improved by addition of an adjuvant. Toxic to bees; do not spray directly or allow to drift onto blooming crops or weeds where bees are foraging.

B. SPINETORAM (Delegate WG) 4.5–7 oz/acre 4 1 MODE-OF-ACTION GROUP NUMBER1: 5 COMMENTS: Toxic to bees; do not spray directly or allow to drift onto blooming crops or weeds where bees are

foraging. C. METHOMYL* (Lannate SP) 0.5–1 lb/acre 3 days 1 MODE OF ACTION GROUP NUMBER1: 1A COMMENTS: The use of this material causes mite problems. D. ABAMECTIN* (Agri-Mek SC) 2.25–4.25 fl oz 0.5–1 fl oz 12 21 MODE-OF-ACTION GROUP NUMBER1: 6 COMMENTS: May be combined with oil. Do not make more than 2 applications per growing season and allow at



* Permit required from county agricultural commissioner for purchase or use. ‡ Preharvest interval. Do not apply within this many days of harvest.

— Not recommended or not on label.


(8/15) Armillaria Root Rot (Oak Root Fungus) 62 Online with photos at http://www.ipm.ucanr.edu/PMG/selectnewpest.nectarine.html

Diseases (Section reviewed 6/10)

ARMILLARIA ROOT ROT (OAK ROOT FUNGUS) (8/15) Pathogen: Armillaria mellea SYMPTOMS AND SIGNS Roots infected with Armillaria mellea have white to yellowish, fan-shaped mycelial mats between the bark and the wood. Dark brown to black rhizomorphs sometimes can be seen on the root surface. All stone fruit rootstocks are susceptible sometimes to Armillaria root rot. The plum rootstock Marianna 2624 has some tolerance and may be useful in some situations. COMMENTS ON THE DISEASE The fungus survives within dead and living roots and as rhizomorphs in the soil. MANAGEMENT Avoid planting nectarine orchards where forest or oak woodland has recently been cleared or where there is a history of Armillaria root rot. All rootstocks can be attacked by Armillaria mellea but some are less affected than others. Maintain the vigor of the trees to help resist Armillaria attack. Infested sites can be fumigated, but often this procedure will not prevent recurrence of the disease. Physical barriers to contain infection centers have been used successfully in orchards. Four-foot trenches are dug around the infection center and plastic tarp is laid inside the trench wall from bottom to top before the soil is replaced. The tarp prevents healthy roots from coming in contact with diseased ones, thus preventing spread of the disease. Cultural Control Research on other tree crops has indicated that exposing an infected crown and upper root area of a tree infected with Armillaria mellea may help to slow the development of the fungus into the crown area. In spring, remove soil from around the base of the tree to a depth of 9 to 12 inches. Leave the trunk exposed for the remainder of the growing season. During the spring, summer, and fall, keep the upper roots and crown area as dry as possible. During winter, provide drainage if necessary so that rain doesn't collect in the hole. Recheck the hole every few years to make sure it has not filled in with leaves, soil, and other matter; the hole must be kept open and the crown and upper roots exposed. Organically Acceptable Methods Cultural controls are acceptable for use in an organically certified crop. Chemical Control Before fumigating, remove all infected trees, stumps, and as many roots greater than 1 inch in diameter as possible. Healthy-appearing trees adjacent to those showing symptoms are often infected also. Removal of these adjacent trees and inclusion of that ground in the soil fumigation may be advisable. Infected trees, stumps, and roots should be burned at the site or disposed of in areas where flood waters cannot wash them to agricultural lands. Complete eradication is rarely achieved, and retreatment may be necessary in localized areas. If the soil is wet or if it has extensive clay layers to the depths reached by the roots, fumigant treatment may not be successful. The greatest opportunity for eradication occurs on shallow soils less than 5 feet in depth. Fumigate from late summer to early fall.


(8/15) Armillaria Root Rot (Oak Root Fungus) 63 Online with photos at http://www.ipm.ucanr.edu/PMG/selectnewpest.nectarine.html


Amount per acre

REI‡ (hours)

PHI‡ (days)

UPDATED 8/15 When choosing a pesticide, consider its usefulness in an IPM program by reviewing the pesticide’s properties, efficacy, application timing, and information relating to resistance management, honey bees, andenvironmental impact. Not all registered pesticides are listed. Always read the label of the product being used. A. METHYL BROMIDE* Label rates See label See label COMMENTS: Must be applied under a Critical Use Exemption. For preplant fumigation. Before fumigating, dry soil

by withholding water during summer and using cover crops such as sudangrass or safflower. The drier the soil the better for deep penetration. Deep-till the area after drying. If the soil is dusty, wait for an early rain before ripping and fumigation. Ripping a dry soil that is silty can result in large clods on the surface. Inject methyl bromide 18–30 inches deep with chisels and cover with gas-proof cover. Increasing the dose tends to increase the depth of penetration, but it cannot be relied upon to penetrate wet soils, especially if soils are high in clay. Do not remove the cover for at least 2 weeks and aerate 1 month before planting. Fumigants such as methyl bromide are a source of volatile organic compounds (VOCs) but are not reactive with other air contaminants that form ozone; methyl bromide depletes ozone.

B. CHLOROPICRIN* Label rates See label See label




(8/15) Bacterial Canker 64 Online with photos at http://www.ipm.ucanr.edu/PMG/selectnewpest.nectarine.html

BACTERIAL CANKER (8/15) Pathogen: Pseudomonas syringae SYMPTOMS AND SIGNS Symptoms are most obvious in spring and include limb dieback with rough cankers and amber-colored gum. There may also be leaf spot and blast of young flowers and shoots. The sour-sap phase of bacterial canker may not show gum and cankers, but the inner bark is brown, fermented, and sour smelling. Flecks and pockets of bacterial invasion in bark occur outside canker margins. Frequently, trees sucker from near ground level; cankers do not extend below ground. COMMENTS ON THE DISEASE Pseudomonas syringae is a ubiquitous bacterium that survives in or on plant surfaces, is spread by splashing rain, and is favored by high moisture and low temperatures in spring. The disease is worse in low or sandy spots in the orchard. Vigorous trees are less susceptible to bacterial canker, while young trees, 2 to 8 years old, are most affected. The disease complex rarely occurs in the first year of planting and is highly uncommon in nurseries. It is a frequent problem in replant situations; however, the severity of bacterial canker in an orchard is highly correlated with the presence of ring nematode in the soil. MANAGEMENT The key to managing bacterial canker is keeping the trees as tolerant as possible to the disease rather than trying to kill the bacterial pathogen. Problems with bacterial canker can be minimized at planting by carefully selecting the planting site, choosing the least susceptible rootstocks, and following recommended cultural practices regarding pruning and fertilizing. Bacterial canker tends to mostly affect weak trees, so any management practice that improves tree vigor (e.g., lighter, more frequent irrigation, improved tree nutrition, nematode management, etc.) will help to reduce the incidence of this disease. Delayed pruning may help. Lovell peach and Viking rootstocks are usually more tolerant than Nemaguard. In light, sandy soils and in some heavy soils, control has been achieved with preplant fumigation for ring nematodes. Applications of copper are not effective against bacterial canker. Organically Acceptable Methods Cultural controls are acceptable for use in an organically certified crop. Chemical Control Bactericide applications have no reliable effect on bacterial canker and their use is not recommended. Preplant fumigation for nematode control reduces the severity of bacterial canker in newly planted orchards. Ring nematodes stress trees, which predispose them to bacterial canker. The benefits of preplant soil fumigation for control of bacterial canker usually last only a few years, and in some areas only limited improvements in disease control occur following soil fumigation. Following planting, if bacterial canker occurs in an orchard, apply nematicide around all trees in the affected area of the orchard on a yearly basis until the trees are 8 years old.


(8/15) Bacterial Canker 65 Online with photos at http://www.ipm.ucanr.edu/PMG/selectnewpest.nectarine.html


Amount per acre

REI‡ (hours)

PHI‡ (days)

UPDATED 8/15

When choosing a pesticide, consider its usefulness in an IPM program by reviewing the pesticide’s properties, efficacy, application timing, and information relating to resistance management, honey bees, andenvironmental impact. Not all registered pesticides are listed. Always read the label of the product being used.

PREPLANT A. METHYL BROMIDE* Label rates See label See label COMMENTS: Must be applied under a Critical Use Exemption. Use higher rates for fine-textured soils. Fumigants

such as methyl bromide are a source of volatile organic compounds (VOCs) but are not reactive with other air contaminants that form ozone; methyl bromide depletes ozone. Fumigate only as a last resort when other management strategies have not been successful or are not available.

B. 1,3-DICHLOROPROPENE* (Telone II) 27–35 gal 5 days NA COMMENTS: This restricted-use product is applied only by professional fumigation companies.. In California the

applications must be applied to soils having a moist surface; this task is difficult to achieve without use of sprinklers unless there is a fortunate rainfall. Do not flood irrigate prepared lands to achieve this surface moisture requirement. Broadcast apply where nematode resistance is unavailable for prevailing nematodes. Fumigants such as 1,3-dichloropropene are a source of volatile organic compounds (VOCs) but are minimally reactive with other air contaminants that form ozone. Fumigate only as a last resort when other management strategies have not been successful or are not available.


* Permit required from county agricultural commissioner for purchase or use. NA Not applicable.


(8/15) Brown Rot Blossom and Twig Blight 66 Online with photos at http://www.ipm.ucanr.edu/PMG/selectnewpest.nectarine.html

BROWN ROT BLOSSOM and TWIG BLIGHT (8/15) Pathogens: Monilinia fructicola, occasionally Monilinia laxa SYMPTOMS AND SIGNS Young blossom spurs and associated leaves collapse to form shoot blight. Gum exudes at base of infected flowers. Cankers on blighted twigs have tan centers with dark margins. Gray brown spore masses form on diseased flower parts and twig cankers under high humidity. Monilinia fructicola overwinters on mummified fruit that either fall to the ground in late fall or early winter, or remain in the trees. In spring, apothecia form on mummies that are on the ground; these apothecia release ascospores at the same time as the trees bloom. Ascospores serve as primary inoculum for brown rot in many orchards. Mummies in the trees as well as those on the ground may also produce conidia, which may serve as the primary source of inoculum in some years. Twig lesions apparently do not produce spores. COMMENTS ON THE DISEASE Although all flower parts except the sepals are susceptible to infection by M. fructicola, only infection of the stamens leads to the development of blossom and twig blight. MANAGEMENT Bloom sprays to reduce blossom and twig blight help minimize loss to ripe fruit rot at harvest. Removal of fruit remaining on trees soon after harvest and before they become mummies may help prevent reinfection of blossoms the following bloom. Chemical Control Make a treatment at 20 to 40% bloom and again at 80 to 100% bloom on susceptible varieties or if heavy rainfall and other conditions are occurring that result in high susceptibility to infection. Early season varieties, especially the low-chilling ones, only need a single spray. Aerial applications are generally not as effective as properly applied ground sprays but may be necessary when the orchard floor is wet. To help reduce development of resistance to fungicides, be sure to rotate chemicals that have different mode of action Group numbers.


Amount per acre

REI‡ (hours)

PHI‡ (days)

UPDATED 8/15

When choosing a pesticide, consider its usefulness in an IPM program by reviewing the pesticide’s properties, efficacy, application timing, and information relating to resistance management, honey bees, andenvironmental impact. Not all registered pesticides are listed. Always read the label of the product being used. A. TEBUCONAZOLE+TRIFLOXYSTROBIN (Adament 50WG) 4–8 oz 5 days 1 MODE-OF-ACTION GROUP NAME (NUMBER1): Demethylation inhibitor (3) and Quinone outside inhibitor (11) B. PROPICONAZOLE (Bumper, Tilt) 4 oz 12 0 MODE-OF-ACTION GROUP NAME (NUMBER1): Demethylation inhibitor (3) C. TEBUCONAZOLE (Elite 45WP) 4–8 oz 5 days 0 MODE-OF-ACTION GROUP NAME (NUMBER1): Demethylation inhibitor (3) COMMENTS: Do not apply more than 3 lb/acre per season. D. FENBUCONAZOLE (Indar 2F) 6 oz 12 0 MODE-OF-ACTION GROUP NAME (NUMBER1): Demethylation inhibitor (3) COMMENTS: Do not apply more than 1 lb/acre per season. E. IPRODIONE


(8/15) Brown Rot Blossom and Twig Blight 67 Online with photos at http://www.ipm.ucanr.edu/PMG/selectnewpest.nectarine.html


Amount per acre

REI‡ (hours)

PHI‡ (days)

UPDATED 8/15 (Rovral 4) 1–2 pt 24 See comments MODE-OF-ACTION GROUP NAME (NUMBER1): Dicarboximide (2) COMMENTS: Addition of a narrow range oil (superior, supreme) at 1–2% increases the effectiveness of this material.

May not be used after petal fall. F. METCONAZOLE (Quash) 2.5–3.5 oz 12 14 MODE-OF-ACTION GROUP NAME (NUMBER1): Demethylation inhibitor (3) COMMENTS: Do not make more than 3 applications per season. G. PYRACLOSTROBIN+BOSCALID (Pristine) 10.5–14.5 oz 12 0 MODE-OF-ACTION GROUP NAME (NUMBER1): Quinone outside inhibitor (11) and Carboxamide (7) H. THIOPHANATE METHYL (Topsin-M 70WP) 1 ½ lb 12 1 MODE-OF-ACTION GROUP NAME (NUMBER1): Methyl benzimidazole (1) COMMENTS: Strains of Monilinia fructicola resistant to thiophanate methyl are common, especially in the Sacramento

and northern San Joaquin Valleys. If resistance has occurred in your orchard, do not use this fungicide; otherwise, one application at early bloom is usually sufficient. If brown rot is severe, or an extended bloom period is accompanied by rainfall, make a second application using a fungicide with a different group number.

I. CYPRODINIL (Vangard WG) 10 oz 12 2 MODE-OF-ACTION GROUP NAME (NUMBER1): Anilinopyrimidine (9) COMMENTS: Do not apply more than 10 oz/acre per year. J. PYRIMETHANIL (Scala SC) 18 fl oz 12 2 MODE-OF-ACTION GROUP NAME (NUMBER1): Anilinopyrimidine (9) COMMENTS: Do not apply within 2 days of fruit harvest or make more than 2 applications of a Group 9 fungicide

within 30 days of harvest. K. FENHEXAMID (Elevate 50WDG) 1–1.5 lb 12 0 MODE-OF-ACTION GROUP NAME (NUMBER1): Hydroxyanilide (17) COMMENTS: Do not apply more than 6 lb/acre per season and avoid making more than 2 consecutive applications

with this material.

L. MYCLOBUTANIL (Rally 40W) 2.5–6 oz 24 0 MODE-OF-ACTION GROUP NAME (NUMBER1): Demethylation inhibitor (3) COMMENTS: Do not apply more than 3.25 lb/acre per season.


1 Group numbers are assigned by the Fungicide Resistance Action Committee (FRAC) according to different modes of actions (for more information, see http://www.frac.info/). Fungicides with a different group number are suitable to alternate in a resistance management program. In California, make no more than one application of fungicides with mode of action Group numbers 1,4,9,11, or 17 before rotating to a fungicide with a different mode of action Group number; for fungicides with other Group numbers, make no more than two consecutive applications before rotating to a fungicide with a different mode of action Group number.


(8/15) Crown Gall 68 Online with photos at http://www.ipm.ucanr.edu/PMG/selectnewpest.nectarine.html

CROWN GALL (8/15) Pathogen: Agrobacterium tumefaciens SYMPTOMS Crown gall appears as rough, abnormal galls on roots or trunk. Galls are soft and spongy. The center of older galls decay. Young trees become stunted; older trees often develop secondary wood rots. COMMENTS ON THE DISEASE The bacteria survive in gall tissue and in soil. Crown gall is most damaging to young trees, either in the nursery or new orchard plantings. All nectarine rootstocks are susceptible to crown gall. MANAGEMENT The incidence of crown gall can be reduced by planting noninfected, “clean" trees. It is also important to carefully handle trees to avoid injury as much as possible, both at planting and during the life of the tree in the orchard. Preplant, preventive dips or sprays with a biological control agent are available and may be helpful in some orchards. Generally, by the time crown gall is evident in a nectarine orchard, it is usually best to tolerate the problem for the few remaining years of orchard life, which is about 12-15 years, or just remove the orchard and start anew. When replanting a previously affected site, remove as many of the old tree roots as possible, grow a grass rotation crop to help degrade leftover host material and reduce pathogen levels, and offset the new trees from the previous tree spacing to minimize contact of healthy new roots with any infested roots that may remain.


Amount per acre

REI‡ (hours)

PHI‡ (days)

UPDATED 8/15

When choosing a pesticide, consider its usefulness in an IPM program by reviewing the pesticide’s properties, efficacy, application timing, and information relating to resistance management, honey bees, andenvironmental impact. Not all registered pesticides are listed. Always read the label of the product being used. A. AGROBACTERIUM TUMEFACIENS-84# (Galltrol-A) Label rates 12 0 COMMENTS: Preventive preplant treatment only. B. GALLEX Label rates 0 0 COMMENTS: For removal of existing galls, apply winter through spring.

# Acceptable for use on organically grown produce. ‡ Restricted entry interval (REI) is the number of hours (unless otherwise noted) from treatment until the treated area can be



(8/15) Jacket Rot 69 Online with photos at http://www.ipm.ucanr.edu/PMG/selectnewpest.nectarine.html

JACKET ROT (8/15) Pathogens: Botrytis cinerea, Sclerotinia sclerotiorum, Monilinia laxa, and Monilinia fructicola SYMPTOMS AND SIGNS Jacket rot occurs during the jacket stage when remnants of the flower parts are still attached to the fruit. The disease causes a brown discoloration on the fruit under the jacket. The young fruit withers and falls off the tree within a few weeks. COMMENTS ON THE DISEASE Development of jacket rot is favored by wet weather and frost during the bloom and jacket stage. MANAGEMENT One fungicide application at full bloom is generally effective. Fungicides applied during the jacket stage are generally much less effective. Treat at full bloom or shortly thereafter but before petal fall. The final bloom spray for blossom brown rot often provides jacket rot control if appropriate fungicides (e.g., iprodione, thiophanate-methyl, pyraclostrobin + boscalid, cyprodinil, etc.) are chosen.


Amount per acre

REI‡ (hours)

PHI‡ (days)

UPDATED 8/15

When choosing a pesticide, consider its usefulness in an IPM program by reviewing the pesticide’s properties, efficacy, application timing, and information relating to resistance management, honey bees, andenvironmental impact. Not all registered pesticides are listed. Always read the label of the product being used. A. TEBUCONAZOLE+TRIFLOXYSTROBIN (Adament 50WG) 4–8 oz 5 days 1 MODE-OF-ACTION GROUP NAME (NUMBER1): Demethylation inhibitor (3) and Quinone outside inhibitor (11) B. PROPICONAZOLE (Bumper, Tilt) 4 oz 12 0 MODE-OF-ACTION GROUP NAME (NUMBER1): Demethylation inhibitor (3) C. TEBUCONAZOLE (Elite 45WP) 4–8 oz 5 days 0 MODE-OF-ACTION GROUP NAME (NUMBER1): Demethylation inhibitor (3) COMMENTS: Do not apply more than 3 lb/acre per season. D. FENBUCONAZOLE (Indar 2F) 6 oz 12 0 MODE-OF-ACTION GROUP NAME (NUMBER1): Demethylation inhibitor (3) COMMENTS: Do not apply more than 1 lb/acre per season. E. IPRODIONE (Rovral 4) 1–2 pt 24 See comments MODE-OF-ACTION GROUP NAME (NUMBER1): Dicarboximide (2) COMMENTS: Addition of a narrow range oil (superior, supreme) at 1–2% increases the effectiveness of this material.

Do not use after petal fall. F. THIOPHANATE-METHYL (Topsin-M 70WP) 1 ½ lb 12 1 MODE-OF-ACTION GROUP NAME (NUMBER1): Methyl benzimidazole (1) COMMENTS: A benzimidazole fungicide. Apply thiophanate methyl in combination with another fungicide of

different chemistry. G. PYRACLOSTROBIN+BOSCALID (Pristine) 10.5–14.5 oz 12 0 MODE-OF-ACTION GROUP NAME (NUMBER1): Quinone outside inhibitor (11) and Carboxamide (7) COMMENTS: A strobilurin and carboxyanilide fungicide. To reduce the potential for the development of resistance,

do not make more than five applications per season of Pristine or other strobilurin or carboxyanilide fungicides.


(8/15) Jacket Rot 70 Online with photos at http://www.ipm.ucanr.edu/PMG/selectnewpest.nectarine.html


Amount per acre

REI‡ (hours)

PHI‡ (days)

UPDATED 8/15 H. CYPRODINIL (Vangard WG) 10 oz 12 2 MODE-OF-ACTION GROUP NAME (NUMBER1): Anilinopyrimidine (9) COMMENTS: Anilinopyrimidine fungicide. I. FENHEXAMID (Elevate 50WDG) 1–1.5 lb 12 0 MODE OF ACTION GROUP NAME (NUMBER1): Hydroxyanilide (17) COMMENTS: A hydroxyanilide fungicide. Do not apply more than 6 lb/acre per season and avoid making more

than 2 consecutive applications with this material. J. DICLORAN (Botran 75-W) 2 lb 12 10 MODE-OF-ACTION GROUP NAME (NUMBER1): Aromatic hydrocarbon (14) COMMENTS: An aromatic hydrocarbon fungicide. K. CHLOROTHALONIL (Echo 720) 3.125–4.125 pt 12 See comments (Bravo Ultrex) 2.8–3.8 lb 12 See comments (Bravo Weather Stik) 3 1/8 – 4 1/8 pt 12 See comments MODE-OF-ACTION GROUP NAME (NUMBER1): Multi-site contact (M5) COMMENTS: An aromatic nitrile fungicide. May cause an allergic skin reaction in some people. Do not use with or

closely following oil sprays. Do not apply after jacket (shuck) split. L. CAPTAN (Captan 50WP) 4–8 lb 24 See comments MODE-OF-ACTION GROUP NAME (NUMBER1): Multi-site contact (M4) COMMENTS: A phthalamide fungicide. Do not apply in combination with, immediately before, or closely following

oil sprays. Do not apply after 75% petal fall.




(8/15) Peach Leaf Curl 71 Online with photos at http://www.ipm.ucanr.edu/PMG/selectnewpest.nectarine.html

PEACH LEAF CURL (8/15) Pathogen: Taphrina deformans SYMPTOMS AND SIGNS Leaves produced in spring are thickened, curled, and colored red or yellow instead of normal green. Severely affected shoots die. Irregular, reddish lesions are sometimes seen on fruit. Badly diseased leaves fall by early summer, and repeated infections debilitate trees and kill branches. After fall and winter rains, spores (blastospores) of the fungus may be observed as a white bloom on the surface of leaves and be found on twigs, buds, and in between bud scales. COMMENTS ON THE DISEASE Taphrina deformans survives on tree surfaces and buds and is favored by cool wet weather during spring. The pathogen most likely survives the warm, dry summer period as ascospores. With fall and winter rains, the ascospores germinate and form numerous budding blastospores. Tree to tree spread of the pathogen occurs by airborne ascospores, which can move longer distances or by blastospores that are disseminated in splashing water. Leaves and the occasional fruit infections occur only on young plant tissue. MANAGEMENT Peach leaf curl can be a serious problem, especially on many of the low-chilling varieties and when spring weather is unusually wet. Annual management is recommended. To successfully control the disease, treatment timing is crucial. This disease is usually kept under control with a dormant fungicide application, but in wet years more than one spray application may be needed. Organically Acceptable Methods Spraying with Bordeaux mixture or copper is acceptable in an organically certified crop. Chemical Control Most copper products have long residual activity, even during prolonged wetness. Therefore, one application in the dormant/delayed-dormant period is sufficient except in areas of high rainfall or where leaf curl has become an increasing problem. In such cases, an added application at delayed dormancy in late winter or before bud swell is recommended. Recently, formulations of fixed coppers have been developed with reduced metallic copper equivalent (MCE). Residual activity is very important to control peach leaf curl and these products, when lower rates are used (e.g. 1.2 to 2.1 lbs per acre MCE for reduced MCE fixed coppers, compared to 3 to 5 lbs per acre MCE for fixed coppers or even 8 to 10 lb per acre MCE for basic copper sulfate), have not been as efficacious over long rainy winter seasons. If using the newer reduced-MCE products: • always use the upper label rate, • consider using a sticker or winter oil as an adjuvant to increase persistence, and • plan to make two applications.

Several other fungicides that are equivalent or even more effective than copper for managing peach leaf curl are Ziram, chlorothalonil (Echo or Bravo), and dodine (Syllit) when applied at the optimal time. Ziram is most effective.

1. Apply in late November or early December after most leaves have fallen from trees to ensure excellent coverage of branches, stems, and buds and before significant late fall and winter rainfall occurs. (This spray will also control shot hole disease, caused by, Wilsonomyces carpophilus).

2. Apply an additional January or early February treatment if high rainfall occurs in December and early January.

3. In addition to January or early February treatments, apply during pre-bloom (at bud swell or two weeks before bloom) if high rainfall occurs in February.

To increase fungicide persistence of the materials, use an adjuvant such as an oil or a sticker.


(8/15) Peach Leaf Curl 72 Online with photos at http://www.ipm.ucanr.edu/PMG/selectnewpest.nectarine.html


Amount per acre

REI‡ (hours)

PHI‡ (days)

UPDATED 8/15

When choosing a pesticide, consider its usefulness in an IPM program by reviewing the pesticide’s properties, efficacy, application timing, and information relating to resistance management, honey bees, andenvironmental impact. Not all registered pesticides are listed. Always read the label of the product being used. A. ZIRAM (Ziram 76DF) 8–10 lb 48 30 MODE-OF-ACTION GROUP NAME (NUMBER1): Multi-site contact, Dithiocarbamates (M3) COMMENTS: While not a preferred timing, if heavy rains are occurring as leaves are emerging in spring or disease

symptoms are present, an application of Ziram can be beneficial in helping to reduce the spread of the fungus. Apply treatments at a minimum of 100 gals water/acre. Higher gallonage (120-150 gals/acre) generally improves coverage.

B. FIXED COPPER# (various products) Label rates See label See label MODE-OF-ACTION GROUP NAME (NUMBER1): Multi-site contact, Inorganic metal (M1) COMMENTS: Not all copper compounds are approved for use in organic production; check product. C. CHLOROTHALONIL (Echo 720) 3.125–4.125 pt 12 See comments (Bravo Ultrex) 2.8–3.8 lb 12 See comments (Bravo Weather Stik) 3 1/8 – 4 1/8 pt 12 See comments MODE-OF-ACTION GROUP NAME (NUMBER1): Multi-site contact, isophthalonitriles (M5) COMMENTS: Do not use with or closely following oil sprays. Plan to make at least two applications in northern

nectarine production areas of California where higher rainfall occurs. A single application may be sufficient in southern nectarine growing districts of California. Apply treatments at a minimum of 100 gals water/acre. Higher gallonage (120-150 gals/acre) generally improves coverage. Do not apply after jacket (shuck) split.

D. BORDEAUX MIXTURE# 10:10:100 Label rates See label See label MODE-OF-ACTION GROUP NAME (NUMBER1): Multi-site contact, Inorganic metal (M1) COMMENTS: For information on making Bordeaux mixture, see UC IPM Pest Note: Bordeaux Mixture, ANR

Publication 7481, available online. Check copper label to determine if organically acceptable.


# Acceptable for use on organically grown produce. 1 Group numbers are assigned by the Fungicide Resistance Action Committee (FRAC) according to different modes of actions

(for more information, see http://www.frac.info/). Fungicides with a different group number are suitable to alternate in a resistance management program. In California, make no more than one application of fungicides with mode of action Group numbers 1,4,9,11, or 17 before rotating to a fungicide with a different mode of action Group number; for fungicides with other Group numbers, make no more than two consecutive applications before rotating to a fungicide with a different mode of action Group number.

NA Not applicable.


(8/15) Phytophthora Root and Crown Rot 73 Online with photos at http://www.ipm.ucanr.edu/PMG/selectnewpest.nectarine.html

PHYTOPHTHORA ROOT and CROWN ROT (8/15) Pathogen: Phytophthora spp. SYMPTOMS AND SIGNS Symptom expression depends upon how much of the root or crown tissues are affected and how quickly they are destroyed. Generally, crown rots advance rapidly and trees collapse and die soon after the first warm weather of spring. Leaves of such trees wilt, dry, and remain attached to the tree. Chronic infections, usually in the roots, cause reduction in growth and early senescence and leaf fall; leaf tissue or veins often turn red. These trees may be unthrifty for several years before succumbing to the disease. Phytophthora infections typically kill young trees because their root systems and crown areas are small compared to those of mature trees. COMMENTS ON THE DISEASE Periods of 24 hours or more of saturated soil favor Phytophthora infections. Conversely, good soil drainage and more frequent but shorter irrigations reduce the risk of root and crown rot. Rootstocks vary in susceptibility to the different Phytophthora species; none are resistant to all pathogenic species of the fungus. Thus, the success of a rootstock may depend in part upon the species of Phytophthora present in the orchard. MANAGEMENT The most effective ways to manage Phytophthora root and crown rot are to select a good planting site, select an appropriate rootstock, and properly manage irrigation water. Planting on raised berms can help in managing this disease. Avoid over irrigating, especially in spring and fall when soil temperatures are most conducive to disease development and water use by the tree is low. Chemical Control Fungicides are available to treat soil around newly planted trees. If there is a history of Phytophthora root rot in the orchards and problems are anticipated, treatments may be warranted. Common name (Example trade name)

Amount to use

REI‡ (hours)

PHI‡ (days)

UPDATED 8/15 When choosing a pesticide, consider its usefulness in an IPM program by reviewing the pesticide’s properties, efficacy, application timing, and information relating to resistance management, honey bees, andenvironmental impact. Not all registered pesticides are listed. Always read the label of the product being used. A. FOSETYL-AL (Aliette WDG) 5 lb/100 gal 12 NA MODE-OF-ACTION GROUP NAME (NUMBER1): Phosphonate (33) COMMENTS: NONBEARING TREES ONLY. Foliar spray, 60-day interval. Do not apply more than 5 lbs Aliette/acre

per application. B. PHOSPHORUS ACID (Fosphite) 1–3 qt/acre 4 0 MODE-OF-ACTION GROUP NAME (NUMBER1): Phosphonate (33) COMMENTS: Allow 10 days before applying a copper-based compound following an application of Fosphite. Allow

20 days before applying Fosphite following a treatment with a copper product. Do not apply with copper-based fungicides or fertilizers.

C. MEFENOXAM (Ridomil Gold) Varies with method of

application and size of tree 0 0

MODE-OF-ACTION GROUP NAME (NUMBER1): Phenylamide (4) COMMENTS: Applications made in early spring and fall.


(8/15) Phytophthora Root and Crown Rot 74 Online with photos at http://www.ipm.ucanr.edu/PMG/selectnewpest.nectarine.html


Amount to use

REI‡ (hours)

PHI‡ (days)

UPDATED 8/15



NA Not applicable.


(8/15) Powdery Mildew 75 Online with photos at http://www.ipm.ucanr.edu/PMG/selectnewpest.nectarine.html

POWDERY MILDEW (8/15) Pathogens: Sphaerotheca pannosa and Podosphaera leucotricha SYMPTOMS AND SIGNS Symptoms of powdery mildew can be seen on the terminal leaves of shoots, which are covered in powdery, white fungal growth. Leaves become misshapen and puckered, and fruits develop powdery white spots that cause scars on mature fruit. COMMENTS ON THE DISEASE Sphaerotheca pannosa survives as mycelium in bud scales and as cleistothecia. Growth of the pathogen is favored by cool, moist nights and warm days. Generally, fruit is susceptible only up to time of pit hardening, but later infections can occur. Certain cultivars are more susceptible. Occasionally the apple powdery mildew fungus, Podosphaera leucotricha, will attack nectarine fruit. Inoculum is produced only in apple orchards. MANAGEMENT Management of powdery mildew on nectarines focuses on protecting fruit from infections. Watch for the disease during routine monitoring. Avoid growing nectarines near apple varieties that are highly susceptible to powdery mildew, such as Jonathan, Gravenstein, and Rome Beauty. If nearby apples are expected to cause mildew problems on nectarines, control the disease on apples or apply a fungicide to nectarines at jacket split. Organically Acceptable Methods Sulfur sprays are acceptable for use in an organically certified crop. Chemical Control Apply one of the fungicides listed below from bloom until pit hardening or later when necessary. Up to three applications may be necessary in seasons when nights are cool and moist and daytime temperatures are warm. Early treatments are the most important and most effective. It is important to alternate materials of a different chemistry to prevent the development of resistance to a fungicide.


Amount per acre

REI‡ (hours)

PHI‡ (days)

UPDATED 8/15 When choosing a pesticide, consider its usefulness in an IPM program by reviewing the pesticide’s properties, efficacy, application timing, and information relating to resistance management, honey bees, andenvironmental impact. Not all registered pesticides are listed. Always read the label of the product being used. A. MYCLOBUTANIL (Rally 40WSP) 2.5–6 oz 24 0 MODE-OF-ACTION GROUP NAME (NUMBER1): Demethylation inhibitor (3) B. QUINOXYFEN (Quintec) 7 fl oz 12 7 MODE-OF-ACTION GROUP NAME (NUMBER1): Quinoline (13) COMMENTS: Re-treat at 10 to 14 day interval if necessary. C. SULFUR DUST# 50 lb See label See label MODE-OF-ACTION GROUP NAME (NUMBER1): Multi-site contact (M2) COMMENTS: Do not apply within 3 weeks of an oil application. D. WETTABLE SULFUR# 5–10 lb/100 gal water See label See label MODE-OF-ACTION GROUP NAME (NUMBER1): Multi-site contact (M2) COMMENTS: Do not apply within 3 weeks of an oil application. E. WETTABLE SULFUR# . . . PLUS . . . LIQUID LIME SULFUR# Label rates See label See label


(8/15) Powdery Mildew 76 Online with photos at http://www.ipm.ucanr.edu/PMG/selectnewpest.nectarine.html


Amount per acre

REI‡ (hours)

PHI‡ (days)

UPDATED 8/15 MODE-OF-ACTION GROUP NAME (NUMBER1): Multi-site contact (M2) COMMENTS: Do not apply within 3 weeks of an oil application. F. TEBUCONAZOLE+TRIFLOXYSTROBIN (Adament 50WG) 4–8 oz 5 days 1 MODE-OF-ACTION GROUP NAME (NUMBER1): Demethylation inhibitor (3) and Quinone outside inhibitor (11) G. TEBUCONAZOLE (Elite 45WP) 4–8 oz 5 days 0 MODE-OF-ACTION GROUP NAME (NUMBER1): Demethylation inhibitor (3) COMMENTS: Do not apply more than 3 lb/acre per season. H. PROPICONAZOLE (Bumper, Tilt) 4 oz 12 0 MODE-OF-ACTION GROUP NAME (NUMBER1): Demethylation inhibitor (3) I. FENBUCONAZOLE (Indar 2F) 6 oz 12 0 MODE-OF-ACTION GROUP NAME (NUMBER1): Demethylation inhibitor (3) COMMENTS: Do not apply more than 1 lb/acre per season. J. METCONAZOLE (Quash) 3.5–4 oz 12 14 MODE OF ACTION GROUP NAME (NUMBER1): Demethylation inhibitor (3) COMMENTS: Do not make more than 3 applications per season. K. PYRACLOSTROBIN+BOSCALID (Pristine) 10.5–14.5 oz 12 0 MODE-OF-ACTION GROUP NAME (NUMBER1): Quinone outside inhibitor (11) and Carboxamide (7) COMMENTS: To reduce the potential for resistance, do not make more than 5 applications of this or other Group 11

or 7 fungicides per season. Do not make more than 2 sequential applications of this product. L. THIOPHANATE METHYL (Topsin-M 70WP) 1 ½ lb 12 1 MODE-OF-ACTION GROUP NAME (NUMBER1): Methyl benzimidazole (1)





(8/15) Ripe Fruit Rot 77 Online with photos at http://www.ipm.ucanr.edu/PMG/selectnewpest.nectarine.html

RIPE FRUIT ROT (8/15) Pathogens: Monilinia fructicola, Botrytis cinerea, Rhizopus spp. SYMPTOMS AND SIGNS Ripe fruit rot caused by Monilinia or Botrytis results in firm, circular spots that spread rapidly over fruit. Monilinia causes dark brown lesions on fruit that eventually turn black from the development of pseudosclerotia (fungal tissue), whereas Botrytis causes light tan to grayish lesions with gray spores. Spore masses may grow on the rotted areas. Fruit becomes more susceptible as it ripens. Botrytis-diseased fruit usually do not remain on the tree until next season, but they are present as inoculum sources for the current season's crop. When Monilinia-diseased fruit remain on the tree, they are known as mummies. Rhizopus rot is a postharvest storage problem. The decaying fruit tissue is watery and soft; the fungus is identified by masses of white mycelium with tiny black sporangia that form most abundantly on fruit near the edge of containers. COMMENTS ON THE DISEASE Monilinia and Botrytis can infect uninjured ripening fruit and cause green fruit rot and incipient infections of young fruit. Wetness, either rain or dew, and injury or fruit cracking increases preharvest infection and subsequent rot. Rhizopus spp. invades only ripe fruit that have been injured and the decay is a postharvest concern only. MANAGEMENT Fruit rot is managed by controlling blossom and twig blight in spring, removing blighted twigs when possible, using appropriate levels of nitrogen fertilizer and water, removing or turning under thinned fruit, controlling fruit-feeding insects such as peach twig borer and oriental fruit moth, and making preharvest treatments when necessary. Early maturing cultivars typically have little trouble with ripe fruit rot. Take fruit samples every other week after color break (see PREHARVEST FRUIT SAMPLES) to detect any developing problems in the orchard and a fruit damage sample at harvest to assess the effectiveness of the current year's IPM program and to determine the needs of next year's program (see FRUIT EVALUATION AT HARVEST). Record results for harvest sample. (Example form available online) Organically Acceptable Methods Treatments of sulfur dust are acceptable for use in an organically certified crop. Chemical Control Fungicides are preventive, not eradicative; they must be applied to uninjured fruit before infections occur. Injured fruit cannot be protected from Monilinia or Botrytis rot by preharvest sprays. Preharvest sprays for Monilinia should be applied as needed during the last 4 weeks before harvest. Where Rhizopus fruit rot is a problem, treat 10 days to 1 day before harvest. After harvest, Rhizopus can be controlled by storing the crop at temperatures below 40°F.


Amount per acre

REI‡ (hours)

PHI‡ (days)

UPDATED 8/15

When choosing a pesticide, consider its usefulness in an IPM program by reviewing the pesticide’s properties, efficacy, application timing, and information relating to resistance management, honey bees, andenvironmental impact. Not all registered pesticides are listed. Always read the label of the product being used. A. TEBUCONAZOLE+TRIFLOXYSTROBIN (Adament 50WG) 4–8 oz 5 days 1 MODE-OF-ACTION GROUP NAME (NUMBER1): Demethylation inhibitor (3) and Quinone outside inhibitor (11) B. PROPICONAZOLE (Bumper, Tilt) 4 oz 12 0 MODE-OF-ACTION GROUP NAME (NUMBER1): Demethylation inhibitor (3) COMMENTS: Maximum of 2 preharvest sprays.


(8/15) Ripe Fruit Rot 78 Online with photos at http://www.ipm.ucanr.edu/PMG/selectnewpest.nectarine.html


Amount per acre

REI‡ (hours)

PHI‡ (days)

UPDATED 8/15 C. TEBUCONAZOLE (Elite 45WP) 4–8 oz 5 days 0 MODE-OF-ACTION GROUP NAME (NUMBER1): Demethylation inhibitor (3) COMMENTS: Do not apply more than 3 lb/acre per season. D. FENBUCONAZOLE (Indar 2F) 6 oz 12 0 MODE-OF-ACTION GROUP NAME (NUMBER1): Demethylation inhibitor (3) COMMENTS: Do not apply more than 1 lb/acre per season. E. THIOPHANATE METHYL (Topsin-M 70W) 1 ½ lb 12 1 MODE-OF-ACTION GROUP NAME (NUMBER1): Methyl benzimidazole (1) COMMENTS: One application only per season and always apply with a companion fungicide with a different mode

of action group number. Strains of brown rot resistant to thiophanate methyl have been found in California. If resistance has occurred in your orchard, do not use this fungicide.

F. PYRACLOSTROBIN+BOSCALID (Pristine) 10.5–14.5 oz 12 0 MODE-OF-ACTION GROUP NAME (NUMBER1): Quinone outside inhibitor (11) and Carboxamide (7) G. FENHEXAMID (Elevate 50WDG) 1–1.5 lb 12 0 MODE-OF-ACTION GROUP NAME (NUMBER1): Hydroxyanilide (17) COMMENTS: Do not apply more than 6 lb/acre per season and avoid making more than 2 consecutive applications

of this material. H. MYCLOBUTANIL (Rally 40WSP) 2.5–6 oz 24 0 MODE-OF-ACTION GROUP NAME (NUMBER1): Demethylation inhibitor (3) I. CAPTAN (Captan 50WP) 4–8 lb 24 0 MODE-OF-ACTION GROUP NAME (NUMBER1): Multi-site contact (M4) COMMENTS: Do not apply in combination with, immediately before, or closely following oil sprays. J. SULFUR DUST# 50 lb See label See label MODE-OF-ACTION GROUP NAME (NUMBER1): Multi-site contact (M2) COMMENTS: Do not apply within 3 weeks of an oil application.

POSTHARVEST A. FLUDIOXONIL (Scholar) 8–16 oz/100 gal water NA NA MODE-OF-ACTION GROUP NAME (NUMBER1): Phenylpyrrole (12) COMMENTS: Treats 200,000 lb fruit using a spray-application system.




NA Not applicable.


(8/15) Rust 79 Online with photos at http://www.ipm.ucanr.edu/PMG/selectnewpest.nectarine.html

RUST (8/15) Pathogen: Transchelia discolor SYMPTOMS AND SIGNS Infections of young twigs and leaves are the most common symptoms of rust, but in California, fruit infections may be a major component of the disease as well. Twig Cankers Twig cankers are the first symptoms of the disease in spring. Cankers develop after petal fall on 1-year-old fruiting wood. They appear as blisters and longitudinal splits in the bark about 0.12 to 0.25 inches long. They can most easily be seen using a 20X hand lens. Leaf Lesions Leaf lesions usually develop after cankers form in spring and may continue to develop through summer and into fall. The lesions appear as bright yellow, angular spots on the upper surface of leaves. The lower surface of the leaves contains brown spore masses. A high incidence of early leaf infections may cause midseason defoliation and numerous fruit infections at harvest. Early and severe defoliation also may reduce yields and stimulate the production of new leaves and buds late in the growing season. Fruit Lesions Fruit lesions may develop during the growing season after leaf symptoms. They first develop as small, brownish spots (0.1 inch) with green halos on mature, yellow fruit. When fruit reddens, lesion halos become greenish yellow. The lesions are sunken and extend several millimeters into the fruit. COMMENTS ON THE DISEASE Transchelia discolor survives in twig cankers or on other host parts, and airborne spores depend on wetness for infection. Fruit symptoms may resemble damage caused by stink bugs; confirm rust by the presence of rust spores within the fruit lesion or by leaf or twig symptoms. MANAGEMENT In orchards where rust develops it is managed with a fungicide treatment in spring. If the problem was severe the previous year, several fungicide treatments may be necessary in spring as soon as the trees leaf out. Because damp conditions favor rust development, angle sprinklers to avoid wetting the foliage. Drip irrigation is the least favorable to development of this disease because it doesn't increase the humidity in the orchard as much as flood or furrow irrigation. Take fruit samples every other week after color break (see PREHARVEST FRUIT SAMPLES) to detect any developing problems in the orchard and a fruit damage sample at harvest to assess the effectiveness of the current year's IPM program and to determine the needs of next year's program (see FRUIT EVALUATION AT HARVEST). Record results for harvest sample. (Example form available online) Organically Acceptable Methods Sulfur treatments are acceptable for use in an organically certified crop. Chemical Control To be effective, treatments must be applied before rust symptoms appear on leaves. Examine one-year-old fruiting wood for small blisters or longitudinal splits. If twig cankers are found and rain is forecasted, make a treatment. If wet weather persists, additional applications may be necessary in late May or early June. Disease severity in the preceding year is an important factor in determining potential of disease during current year. Treatment with sulfur is both cost-effective and efficacious. The sterol inhibitors are also efficacious but more expensive than the sulfurs.


(8/15) Rust 80 Online with photos at http://www.ipm.ucanr.edu/PMG/selectnewpest.nectarine.html


Amount per acre

REI‡ (hours)

PHI‡ (days)

UPDATED 8/15


SULFUR TREATMENTS A. WETTABLE SULFUR# 18 lb/100 gal water See label See label MODE-OF-ACTION GROUP NAME (NUMBER1): Multi-site contact (M2) COMMENTS: Do not apply within 3 weeks of an oil application. B. WETTABLE SULFUR+LIQUID LIME SULFUR# Label rates See label See label MODE-OF-ACTION GROUP NAME (NUMBER1): Multi-site contact (M2) COMMENTS: Do not apply within 3 weeks of an oil application. C. LIQUID LIME SULFUR# 6 gal/100 gal water See label See label MODE-OF-ACTION GROUP NAME (NUMBER1): Multi-site contact (M2) COMMENTS: Do not apply within 3 weeks of an oil application. D. SULFUR DUST# 50 lb See label See label MODE-OF-ACTION GROUP NAME (NUMBER1): Multi-site contact (M2) COMMENTS: Do not apply within 3 weeks of an oil application.

STEROL INHIBITOR FUNGICIDES A. TEBUCONAZOLE (Elite 45WP) 5–8 oz 5 days 0 MODE-OF-ACTION GROUP NAME (NUMBER1): Demethylation inhibitor (3) COMMENTS: Do not apply more than 3 lb/acre per season. B. PROPICONAZOLE (Bumper, Tilt) 4 oz 12 0 MODE-OF-ACTION GROUP NAME (NUMBER1): Demethylation inhibitor (3) COMMENTS: Maximum of 2 preharvest sprays. C. METCONAZOLE (Quash) 3.5–4 oz 12 14 MODE-OF-ACTION GROUP NAME (NUMBER1): Demethylation inhibitor (3) COMMENTS: Do not make more than 3 applications per season.

STROBILURIN FUNGICIDE A. AZOXYSTROBIN (Abound) 12–15.5 fl oz 4 0 MODE-OF-ACTION GROUP NAME (NUMBER1): Quinone outside inhibitor (11) COMMENTS: Do not apply more than two applications before alternating with a fungicide that has a different mode

of action group number. B. TRIFLOXYSTROBIN (Gem 500 SC) 4–8 oz 12 1 MODE-OF-ACTION GROUP NAME (NUMBER1): QUINONE OUTSIDE INHIBITOR (11)


# Acceptable for use on organically grown produce. 1 Group numbers are assigned by the Fungicide Resistance Action Committee (FRAC) according to different modes of actions (for

more information, see http://www.frac.info/). Fungicides with a different group number are suitable to alternate in a resistance management program. In California, make no more than one application of fungicides with mode of action Group numbers 1,4,9,11, or 17 before rotating to a fungicide with a different mode of action Group number; for fungicides with other Group numbers, make no more than two consecutive applications before rotating to a fungicide with a different mode of action Group number.


(8/15) Scab 81 Online with photos at http://www.ipm.ucanr.edu/PMG/selectnewpest.nectarine.html

SCAB (8/15) Pathogen: Cladosporium carpophilum SYMPTOMS AND SIGNS Scab affects foliage, young shoots, and fruit, but damage is the result of fruit infections. Fruit infections appear as dark lesions on ripening fruit, most commonly on the upper surface, and may grow together to form large blotches. Lesions may have green or yellowish blotches that turn grayish when spores are produced. COMMENTS ON THE DISEASE Primarily a problem on nectarines in the northern San Joaquin Valley during wet spring weather. The fungus that causes scab overwinters in lesions on first-year twigs. Spores are produce in these lesions when humidity exceeds 70% beginning at bloom and lasting several weeks. Spores are spread by air movement and splashing water and will infect developing fruit, although it may take several weeks for lesions to appear. MANAGEMENT In orchards with a history of scab, applications of a fungicide within 3 weeks after full bloom, and again at 5 weeks if disease was severe the previous year, will reduce fruit infection. Fungicides applied during bloom for brown rot and at petal fall to control shot hole will also reduce the spread of scab if appropriate fungicides are chosen. Take a fruit damage sample at harvest to assess the effectiveness of the current year's IPM program and to determine the needs of next year's program (see FRUIT EVALUATION AT HARVEST). Record results for harvest sample. (Example form available online)


Amount per acre

REI‡ (hours)

PHI‡ (days)

UPDATED 8/15

When choosing a pesticide, consider its usefulness in an IPM program by reviewing the pesticide’s properties, efficacy, application timing, and information relating to resistance management, honey bees, andenvironmental impact. Not all registered pesticides are listed. Always read the label of the product being used. A. TRIFLOXYSTROBIN (Gem 500SC) 4–8 oz 12 1 MODE-OF-ACTION GROUP NAME (NUMBER1): QUINONE OUTSIDE INHIBITOR (11) B. AZOXYSTROBIN (Abound) 12–15.5 fl oz 4 0 MODE-OF-ACTION GROUP NAME (NUMBER1): Quinone outside inhibitor (11) COMMENTS: Do not apply more than two applications before alternating with a fungicide that has a different mode

of action group number. C. FENBUCONAZOLE (Indar 2F) 6 oz 12 0 MODE-OF-ACTION GROUP NAME (NUMBER1): Demethylation inhibitor (3) COMMENTS: Do not apply more than 1 lb/acre per season. D. PYRACLOSTROBIN+BOSCALID (Pristine) 10.5–14.5 oz 12 0 MODE-OF-ACTION GROUP NAME (NUMBER1): Quinone outside inhibitor (11) and Carboxamide (7) COMMENTS: To reduce the potential for resistance, do not make more than 5 applications of this or other Group 11

or 7 fungicides per season. Do not make more than 2 sequential applications of this product. E. CHLOROTHALONIL (Echo 720) 3.125–4.125 pt 12 See comments (Bravo Ultrex) 2.8–3.8 lb 12 See comments (Bravo Weather Stik) 3 1/8 – 4 1/8 pt 12 See comments MODE-OF-ACTION GROUP NAME (NUMBER1): Multi-site contact (M5) COMMENTS: Do not use with or closely following oil sprays. Do not apply after shuck split.


(8/15) Scab 82 Online with photos at http://www.ipm.ucanr.edu/PMG/selectnewpest.nectarine.html


Amount per acre

REI‡ (hours)

PHI‡ (days)

UPDATED 8/15 F. THIOPHANATE METHYL (Topsin-M 70WP) 1 ½ lb 12 1 MODE-OF-ACTION GROUP NAME (NUMBER1): Methyl benzimidazole (1) G. CAPTAN (Captan 50WP) 4–8 lb 24 0 MODE-OF-ACTION GROUP NAME (NUMBER1): Multi-site contact (M4) COMMENTS: Do not apply in combination with, immediately before, or closely following oil sprays. H. ZIRAM (Ziram 76DF) 4 ½ – 8 lb 48 30 MODE-OF-ACTION GROUP NAME (NUMBER1): Multi-site contact (M3)


1 Group numbers are assigned by the Fungicide Resistance Action Committee (FRAC) according to different modes of actions (for more information, see http://www.frac.info/). Fungicides with a different group number are suitable to alternate in a resistance management program. In California, make no more than one application of fungicides with mode of action Group numbers 1, 4, 9, 11, or 17 before rotating to a fungicide with a different mode of action Group number; for fungicides with other Group numbers, make no more than two consecutive applications before rotating to a fungicide with a different mode of action Group number.


(8/15) Shot Hole Disease 83 Online with photos at http://www.ipm.ucanr.edu/PMG/selectnewpest.nectarine.html

SHOT HOLE DISEASE (8/15) Pathogen: Wilsonomyces carpophilus SYMPTOMS AND SIGNS The main symptoms of shot hole on nectarine occur on twigs and buds, but fruit lesions may develop when spring weather is wet. Twig symptoms first appear as small, purplish black spots. These turn brown as they enlarge, often having a light center with a purplish brown margin. Tiny, dark brown bumps develop at the center of each lesion. These bumps are spore-forming structures called sporodochia and are easily seen with a hand lens. When buds are affected, the scales turn dark brown or black and the buds may be covered with a shiny layer of exuded gum. Buds killed by bacterial blast have a similar appearance but tend to be much blacker, and nearby foliage of the affected shoot is wilted. Shot hole can be distinguished on nectarine by the presence of tan twig lesions with dark margins, usually accompanied by profuse gumming. Fruit and leaf symptoms look much like those of twig lesions. They are small spots, purplish at first, and turning light brown in the center as they enlarge. Sporodochia form in leaf lesions but not in fruit lesions. Leaf lesions may be surrounded by a light green or yellowish zone; in many cases the brown tissue in the center will fall out, leaving the “shot hole" that gives the disease its name. COMMENTS ON THE DISEASE Wilsonomyces carpophilus survives on infected twigs and buds. Spores are produced throughout winter and are spread by splashing rain and wind. The disease is favored by prolonged wetness in fall to midwinter (twig blight). Summer rain or sprinkler irrigation encourages fruit infection. There is more infection low in the tree where fruit stay wet longer. MANAGEMENT Shot hole is managed primarily with fungicide treatments to protect buds and twigs from infection. In orchards where twig infections are prevalent, the efficacy of the dormant treatment can be improved by pruning out and destroying infected wood. If the orchard is sprinkler irrigated, be sure to angle sprinkler heads low enough to keep from wetting the canopy. Organically Acceptable Methods Treatment with Bordeaux mixture and some formulations of copper are acceptable for use in an organically certified orchard. Chemical Control Spray at leaf fall or from November 15 to December 1 before winter rains to protect against twig infections. This spray often will also control leaf curl. If needed, make a spring application during bloom to prevent fruit and leaf infection. If weather is wet, look for fruiting structures in leaf lesions. If any are present, treat with a product, such as pyraclostrobin + boscalid, chlorothalonil, or azoxystrobin, that is used for both brown rot and shot hole control.


Amount per acre

REI‡ (hours)

PHI‡ (days)

UPDATED 8/15

When choosing a pesticide, consider its usefulness in an IPM program by reviewing the pesticide’s properties, efficacy, application timing, and information relating to resistance management, honey bees, andenvironmental impact. Not all registered pesticides are listed. Always read the label of the product being used. A. PYRACLOSTROBIN+BOSCALID (Pristine) 10.5–14.5 oz 12 0 MODE-OF-ACTION GROUP NAME (NUMBER1): Quinone outside inhibitor (11) and Carboxamide (7) COMMENTS: To reduce the potential for resistance, do not make more than 5 applications of this or other Group 11

or 7 fungicides per season. Do not make more than 2 sequential applications of this product.


(8/15) Shot Hole Disease 84 Online with photos at http://www.ipm.ucanr.edu/PMG/selectnewpest.nectarine.html


Amount per acre

REI‡ (hours)

PHI‡ (days)

UPDATED 8/15 B. BORDEAUX MIXTURE# 10:10:100 Label rates See label See label MODE-OF-ACTION GROUP NAME (NUMBER1): MULTI-SITE CONTACT (M1) COMMENTS: Not all copper compounds are approved for use in organic production so be sure to check individual

products. C. CHLOROTHALONIL (Echo 720) 3.125–4.125 pt 12 See comments (Bravo Ultrex) 2.8–3.8 lb 12 See comments (Bravo Weather Stik) 3 1/8 – 4 1/8 pt 12 See comments MODE-OF-ACTION GROUP NAME (NUMBER1): Multi-site contact (M5) COMMENTS: Do not use with or closely following oil sprays. Do not apply after shuck split. D. FIXED COPPER# (various products) Label rates See label See label MODE-OF-ACTION GROUP NAME (NUMBER1): Multi-site contact (M1) COMMENTS: Not all copper compounds are approved for use in organic production so be sure to check individual

products. E. ZIRAM (Ziram 76DF) 6 lbs 48 30 MODE-OF-ACTION GROUP NAME (NUMBER1): Multi-site contact (M3) F. AZOXYSTROBIN (Abound) 12–15.5 fl oz 4 0 MODE-OF-ACTION GROUP NAME (NUMBER1): Quinone outside inhibitor (11)




NA Not applicable.


(8/15) Verticillium Wilt 85 Online with photos at http://www.ipm.ucanr.edu/PMG/selectnewpest.nectarine.html

VERTICILLIUM WILT (8/15) Pathogen: Verticillium dahliae SYMPTOMS AND SIGNS Verticillium wilt becomes apparent when leaves on one or more branches, often on only one side of the tree, turn yellow or wilt early in the growing season. The symptoms progress until the infected shoots die and dry up later in the season. When shoot, branch, or trunk tissue of infected trees is dissected, the vascular ring and often much of the heartwood will display dark discoloration. Foliar symptoms usually appear only on young trees (2nd to 4th leaf). Older trees do not normally present symptoms of Verticillium wilt. COMMENTS ON THE DISEASE The causal fungus, Verticillium dahliae, survives from season to season in soil, debris of previous, susceptible crops, and probably in the roots and lower trunk of infected trees. Often the fungus can be isolated from living portions of infected tissue year around in the Central Valley. Tree yields can be reduced by Verticillium even when foliar symptoms are not readily apparent. Specific rootstock/scion varieties may vary in susceptibility and are not well known. MANAGEMENT Orchards can be adversely affected by this disease even when low pathogen numbers in soil (2–3 propagules per gram) are present. Avoid interplanting young orchards with susceptible crop plants, such as cotton, tomatoes, melons, etc. Verticillium dahliae is usually present in these soils. Inoculum levels can be reduced by fumigating the soil, flooding fallow fields in summer, solarizing the soil, growing several seasons of grass cover crops (especially sudangrass or rye), or a combination of these methods. When replanting in an area where susceptible perennials were previously grown, try to remove as many roots of the previous crop as possible. Soil Solarization Preplant Beginning in late spring, cover the moistened soil with clear, UV-inhibited plastic sheeting. Leave in place during the summer months. At Planting Cover soil around trees with black plastic sheeting. Leave in place for one to two growing seasons.


Amount per acre

REI‡ (hours)

UPDATED 8/15


PREPLANT A. METHYL BROMIDE*+CHLOROPICRIN* Label rates See label COMMENTS: Use allowed under a Critical Use Exemption only. Fumigants such as methyl bromide are a source of

volatile organic compounds (VOCs) but are not reactive with other air contaminants that form ozone; methyl bromide depletes ozone.

* Permit required from county agricultural commissioner for purchase or use. ‡ Restricted entry interval (REI) is the number of hours (unless otherwise noted) from treatment until the treated area can be safely

entered without protective clothing.


(8/15) Nematodes 86 Online with photos at http://www.ipm.ucanr.edu/PMG/selectnewpest.nectarine.html

Nematodes (Section reviewed 6/10)

Scientific Names: Root knot nematode: Meloidogyne arenaria, M. hapla, M. incognita, and M. javanica Ring nematode: Mesocriconema (=Criconemella) xenoplax Root lesion nematode: Pratylenchus vulnus and Pratylenchus spp. Dagger nematode: Xiphinema americanum DESCRIPTION OF THE PESTS Nematodes are microscopic roundworms that live in diverse habitats. They feed on plants by puncturing and sucking the cell contents with a spear like mouthpart called a stylet or spear. Of the several types of plant parasitic nematodes detected in California orchard soils, the above species are considered to be the most important. DAMAGE Damage caused by nematodes may become evident as early as the first year after planting, and the damage they do can reduce growth by as much as 10 to 20%. However, if greater than that amount of damage is observed we attribute it to one or more of the other three components of the replant problem. In replant settings involving peach rootstock, the bulk of first year damage is caused by the rejection component of the replant problem and occurs with or without the presence of nematodes. Feeding by root knot nematodes can impair root functions such as uptake of nutrients and water. With minor exceptions, root knot nematodes penetrate at the root tip and within 2 weeks stimulate formation of giant cells just as the vascular tissues of the plant are also becoming apparent. Giant cells are enlarged cells that display multiple nuclei and dense cell walls; they become disruptive of normal vascular function as photosynthetic products are disproportionately diverted into these nematode-feeding sites. Root knot nematodes have been implicated in nectarine disease complexes with fungi and bacteria; for example, Meloidogyne javanica is reported to increase the incidence of crown gall on nectarine roots. Lateral roots may fail to develop normally as they emerge because of feeding damage, and there is eventually a notable reduction of roots plus plentiful galling along infected roots. An important concern with Mesocriconema xenoplax is that it is the ring nematode that predisposes trees of Prunus spp. to bacterial canker. High population levels of this nematode result in greater incidence of bacterial canker, and these elevated population levels are directly related to abundance of large pore spaces within soil. Ring nematodes remain external to the root system as they introduce their lengthy spear into nectarine roots and develop a cellular feeding tube that surrounds the spear. After a week or two the feeding is complete and the smallest roots, their favorite feeding site, are dead. During the first year after planting as much as 85% of the smallest roots can be notably absent. These fine roots do more than supply the tree with nutrients; they are also a source of various plant hormones. Trees infested with ring nematode can also show reduced vigor, but even vigorous trees can display bacterial canker. Root lesion nematode, specifically Pratylenchus vulnus, penetrates nectarine root surfaces and can also enter roots to cause damage as they feed and migrate through root tissues. At high population levels they create channels within the root as they migrate. This impact can provide easy access for bacteria and fungi, but it is also notable that there are fewer large roots on the tree if the infection occurs in the early years of tree growth. Dagger nematodes feed from outside the roots but can reach vascular tissues within the root by using their long stylet. If population levels are high enough and there are other stress agents present, they are capable of reducing vigor and yield of trees. However, the main damage caused by the dagger nematode, Xiphinema americanum, is that it vectors a strain of Tomato ringspot virus that causes peach yellow bud mosaic, which can debilitate and kill trees. California has few examples of this virus because of regulations that clean nursery stock be provided to growers. At the present time this nematode is not as important to nectarine growers as the others mentioned. SYMPTOMS The symptoms described below are indicative of a nematode problem but are not diagnostic because they are general effects of damage to roots and can result from either biotic or abiotic causes.



Symptoms of root knot nematode infestation are reduced vigor and yield, patches of unevenly sized trees, and characteristic galls on roots. Heavily infested trees are more susceptible to moisture stress. Ring nematode infestation can reduce tree vigor but is most noteworthy because predisposes trees to bacterial canker complex, which can cause sudden collapse of limbs or entire trees in spring. Root lesion nematodes reduce overall root presence and tree vigor; upper shoots may die back as a result. Symptoms of dagger nematode infestation include reduced growth and vigor; if the Tomato ringspot virus has been transmitted, yellow bud mosaic disease symptoms may also be seen. Trees newly infected by virus have irregular chlorotic areas and vein clearing (mosaic) on leaf blades. In the second year of infection, the yellow bud phase is expressed in spring as extremely stunted tufts of pale yellow leaves. FIELD EVALUATION It is critical to know which nematode species and the general population levels in order to make rational management decisions before planting. If a previous orchard or crop experienced nematode problems and the intended nectarine rootstock is listed as susceptible to those nematodes, expect population levels to be high enough to cause damage to the young trees and make management decisions accordingly. If the species of nematodes present in the soil have not previously been identified, take soil samples and send them to a diagnostic laboratory for identification. Divide the field into sampling blocks of not more than 5 acres each that are representative of cropping history, different crop vigor, or soil texture. Within each block, take several subsamples randomly from the frequently wetted zones at the edge of the tree canopy or in the drip zone in the case of drip-irrigated orchards. Take samples from within the root zone (6- to 36-inch depth), and include some feeder roots when possible. Mix the subsamples gently but thoroughly, and make a composite sample of about 1 quart (1 liter) for each block. Place the samples in separate plastic bags, seal them, and place a label on the outside with your name, address, location, and the current or previous crop and the crop you intend to grow. It is a good idea to place a duplicate label on a moisture-resistant plastic pot marker inside the bag. Keep samples cool (do not freeze), and transport as soon as possible to a diagnostic laboratory. Contact your farm advisor for more details about sampling, to help you find a laboratory for extracting and identifying nematodes, and for help in interpreting sample results. MANAGEMENT In replant settings the available choices include:

1. Fumigate the soil if the prevailing nematodes are damaging and no nematode resistance is available. 2. Fumigate the soil in the planting strips if rootstocks with resistance are available and the setting is a replant. 3. Avoid fumigation by planting 4 years of non-woody crops that are not nematode hosts. 4. Another method currently under study is to utilize 'starve and switch' in lieu of fumigation. Starve the old

soil ecosystem by applying glyphosate (Roundup) herbicide to cut stumps and then removing the trees after 60 days.

One full year after the glyphosate application, replant on a rootstock with tolerance to the rejection component of the replant problem as well as resistance to prevailing nematode pests. Our best example for Prunus spp. is to replant with Hansen 536 rootstock following Nemaguard unless the soil is sandy, which may lead to the development of large numbers of ring nematode and potentially bacterial canker. More research is needed to find alternative rootstocks suitable for nectarine growers to switch to following Nemaguard. In established orchards there are currently few effective nematicides available. Enzone is effective against ring nematode in highly porous soils at 1,000 ppm applied during cool time periods, before May 1 and after mid-October. Focus on nematode control decision-making before replanting. In finer textured soils the degradation rate of Enzone is so rapid (about 50% per day) that penetration among soil particles can be inadequate. Cultural Practices When replanting, removal of old trunks and any large roots from the previous orchard is important if the fumigation is to be shank applied. If the field is not to be fumigated, one must make extra effort to bring deeper roots to the field surface by ripping and fallow. Smallest roots harbor the greatest number of nematodes within. Application of a glyphosate herbicide just after harvest can greatly reduce incidence of root knot nematode within roots but will not reduce presence of root lesion nematodes. Root killing will however destroy the food source for ectoparasitic nematodes as well as the food source for the entire soil biology. This starvation tactic followed by one full year of waiting is partially useful when replanting without soil fumigation.



If a cover crop is to be planted during the waiting period, choose one that does not host prevailing nematodes. Sudangrass is a good summer choice. Barley, Merced rye, Blando Brome, or Salina Strawberry Clover are useful 'nematode-safe' choices for fall seeding. Contact your farm advisor for further information on the nematode host status of cover crops or rotation crops. Use certified nematode-free rootstocks or seedlings to establish new orchards. When the orchard is developed, use procedures that improve soil tilth and drainage to help reduce nematode damage. Where nematodes are a problem and root systems have become reduced, apply irrigations and nutrients more frequently. In nematode-infested orchards the addition of organic matter can improve water-holding capacity and improve soil tilth; both actions help to alleviate tree stress and thereby the symptoms of nematode damage. The favored organic matter depends on proximity to weed-free feedlots, compost yards, or preference for a particular cover crop. Small amounts of short-lived nematicidal properties may also be present in some of these organic choices, but their primary benefit is soil improvement. By the same token, more frequent irrigations are a side benefit of low-volume irrigation systems, and this tactic can reduce tree stress similar to that achieved with cover crops. Rootstock Selection Nematode-free rootstocks are commonly available as a result of the NIPM #7 program of the California Department of Agriculture. Ninety percent of the nectarine industry in California is planted on Nemaguard rootstock. After half a century, Nemaguard's resistance to all root knot nematode species has not been broken apparently because of a mechanism that destroys the ability of root knot nematode females to reproduce after they have entered roots and established their feeding site. In recent studies of forty-five potential Nemaguard replacements collected from around the world, the ability of Nemaguard rootstock to host root lesion nematode is less than that of two-thirds of these potential replacements. Nemaguard root systems are, however, damaged by ring nematode, and it is among the most difficult to successfully replant because of what is termed the “rejection component" of the replant problem. The rejection component results in very poor orchard development beginning from first leaf and lasting as long as one year. After the first year the growth of the trees unevenly improves unless the trees have been overwatered, organic matter has been added, or damaging nematode pests are present. Lovell seedling rootstock supports about half the ring nematode numbers as Nemaguard and is notably more tolerant of the bacterial canker complex. Its host status for root lesion nematode is similar to that of Nemaguard, but it is completely susceptible to root knot nematodes unless Dactylella oviparasitica, a fungal biological control agent that parasitizes the eggs of Meloidogyne spp., is present and active. If the ground has been fumigated adequately to give several years of root knot nematode relief, this fungus performs quite well in soils south and east of Fresno but not as far south as the Hanford area. While attempts to transport this fungus to other fields have not been successful, when it is present, the population levels of root knot nematode are gone from Lovell seedlings by the fourth leaf. Marianna 2624 and Myrobalan 29C are resistant to root knot nematode. They impart slight tolerance to root lesion nematode, but as with most plum-type rootstocks, are highly susceptible to ring nematode; therefore, the bacterial canker complex is of great concern where these rootstocks are used and the soil is coarse textured. Viking is a relatively new rootstock that for most months of the year displays resistance to ring nematode on par with Lovell. However, during the warmest months it becomes a host of ring nematode. In the presence of bacterial canker it offers relief almost as good as that from Lovell. It is almost as resistant as Lovell to root knot nematode and comparable to Nemaguard against root lesion nematode.

Commonly Used Rootstocks and Their Relative Susceptibility to Important Pathogenic Nematodes

Rootstock Root knot Ring Root Lesion Nemaguard Immune Susceptible Susceptible Lovell Susceptible Somewhat tolerant Susceptible Marianna 2624 Immune Highly susceptible Slightly tolerant Peach/Almond Hybrids (Hansen 536, Nickels, Brights)

Immune Highly susceptible Susceptible

Viking Immune Somewhat tolerant Susceptible Atlas Immune Susceptible Susceptible



When to Treat Established Orchards Established orchards suffering from nematode problems are those from which fruit size and numbers are reduced or in sandier soils tree limbs are dying because of bacterial canker complex. As new postplant nematicides become available, determine their effectiveness by leaving several trees or rows of trees untreated for comparison.


Amount per acre

REI‡ (hours)

PHI‡ (days)

UPDATED 8/15

When choosing a pesticide, consider its usefulness in an IPM program by reviewing the pesticide’s properties, efficacy, application timing, and information relating to resistance management, andenvironmental impact. Not all registered pesticides are listed. Always read the label of the product being used.

PREPLANT A. METHYL BROMIDE* Label rates See label NA COMMENTS: Must be applied under a Critical Use Exemption. Use methyl bromide for fine-textured soils. Apply

methyl bromide as a broadcast fumigation using tarps; by fumigating the soil with 300 lb/acre, inverting the top 12 inches of soil, and re-fumigating in 14 days with 150 lb/acre; or by fumigating a 10- or 11-foot strip down each planting row where soil is too moist to effectively apply Telone and there is resistance to the prevailing nematodes in the new rootstock. Fumigants such as methyl bromide are a source of volatile organic compounds (VOCs) but are not reactive with other air contaminants that form ozone; methyl bromide depletes ozone.

B. METAM SODIUM* (Vapam HL, Sectagon, etc.) 75 gal 48 NA COMMENTS: Metam sodium can effectively reduce populations of nematodes to 5-foot depth if applied properly as

a drench in large volumes of water, but it does not penetrate and kill plant roots deeper than 3.5 feet. This product is best applied in springtime or to pre-moistened soil. Its usefulness is limited to sandier soils or soils that infiltrate 6 to 8 inches of water within 12 hr or less. Can be applied via a series of small level basins (e.g., one tree row at a time) if there is adequate water supply for complete filling of the basins within 1-2 hours. But, for best tree growth, do not replant any Prunus spp. within one year after the drenching of the basins. Fumigants such as metam sodium are a source of volatile organic compounds (VOCs) but are minimally reactive with other air contaminants that form ozone.

C. 1,3-DICHLOROPROPENE* (Telone II) 27–35 gal 5 days NA COMMENTS: In California the applications must be applied to soils having a moist surface; this task is difficult to

achieve without use of sprinklers unless there is a fortunate rainfall. Do not flood irrigate prepared lands to achieve this surface moisture requirement. Broadcast apply where nematode resistance is unavailable for prevailing nematodes. Fumigants such as 1,3-dichloropropene are a source of volatile organic compounds (VOCs) but are minimally reactive with other air contaminants that form ozone.


* Permit required from county agricultural commissioner for purchase or use. NA

Not applicable.


(8/15) Integrated Weed Management 90 Online with photos at http://www.ipm.ucanr.edu/PMG/selectnewpest.nectarine.html

Weeds (Section reviewed 6/10)

INTEGRATED WEED MANAGEMENT (8/15) Integrated weed management is the use of multiple strategies including cultural, mechanical, chemical, and biological methods to manage weed populations in a manner that is economically and environmentally sound. Nectarine orchards may be infested with a variety of annual and perennial weeds, each competing with the trees for water and nutrients. Competition for these resources is of greater concern with young trees because weeds can reduce their growth, vigor, and delay production. Weeds are also a problem in older orchards where they can increase the risk of frost damage early in the season, harbor pests and pathogens, interfere with irrigation systems, compete with the trees for water and nutrients, and impede harvest operations. Integrated weed management strategies vary from orchard to orchard and are influenced by geographic location, climatic conditions, soil texture and profile, irrigation practices, topography, cost, and grower preferences. A good orchard weed management program is composed of preventive strategies, orchard floor management, and weed monitoring. The proper use of pre- and postemergence herbicides and timely discing and cultivation are important factors in weed management. Weeds are commonly controlled either chemically or mechanically in a 4- to 6-foot-wide strip in the tree row. Resident vegetation is generally permitted to grow in the areas between the tree rows but must be managed through repeated mowing, tillage, or chemical treatment. Mulches, subsurface irrigation, flamers, and grazing by animals can also be used to control weeds in orchards. Check local regulations to determine how long before harvest the animals must be removed. PREVENTION Preventing the establishment of new weeds and existing weeds from producing seed are the most cost-effective methods of weed management. Keep the irrigation system, canals, and ditch banks free of weeds and weed seeds. A good drainage system is essential. Fix leakages in the irrigation system. Do not allow accumulation of water in low spots; this will encourage weed emergence and growth. Control weeds on the orchard margins before they produce seeds that disperse into the orchard. When moving equipment from a weed-infested field clean the undercarriage and tires of vehicles and equipment before entering the orchard because seeds and other reproductive parts of weeds can be transported along with them. MONITORING Detection of new weeds and those that escaped previous control efforts is an important component of a weed management plan. Correct identification of weed species, especially in the seedling stage is essential. Annual weeds are easier to control with chemical or mechanical tools when they are small and have not become established. If perennial weeds emerge from seed, control them with cultivation or herbicides before they produce reproductive structures. Established perennial weeds are most vulnerable to control during fall when they begin to store carbohydrates in their roots or reproductive structures in preparation for dormancy. Herbicides applied at this stage will translocate to the roots or rhizomes and provide more effective control than at other times during the year. Many herbicides are effective only against certain weed species. Regular monitoring will help to properly choose and time treatments. Follow-up monitoring allows you to assess if treatments are successful. Weeds often grow in patches and, therefore, it may not be necessary to spray postemergence herbicides or apply mechanical control in the whole orchard. The use of hand weeding or a spot treatment of herbicides may save time and money while achieving good weed control. How to Monitor Survey your orchard for weeds in late fall and again in late spring. Record and map infestations, paying particular attention to perennial and other problem weeds, and note their location on the map. Record weeds found in rows and middles separately. Weeds in tree rows must be managed, but annual weeds in row middles may be beneficial as a cover crop. Keep records of weed management actions including timing, rates and dates of



herbicide applications, and cultivations. Survey information collected over a period of years will show the spectrum of weeds present and help determine the most effective control strategy. Late Fall Weed Survey Survey your orchard in fall after the first rains when winter annuals have begun to germinate. Monitoring weeds in fall will identify any summer species and perennial weeds that escaped the previous year's weed control program. Adjustments can be made to control these weed species next year. Fall monitoring will also identify any winter species that are emerging. Record your observations on the fall-weed survey form (available online) and use the map to show areas of problem weeds. Late Spring Weed Survey Survey your orchard in late spring or early summer, after summer annuals have germinated. By surveying weeds at this time, you can identify any species that escape control from earlier management and know what perennials are present. If herbicides were used, monitoring identifies if there is a need to change to another herbicide. Pay particular attention to perennials, and check for their regrowth a few weeks after cultivation. Record your observations on the late-spring weed survey form (available online) and use the map to show areas of problem weeds. ORCHARD FLOOR MANAGEMENT Benefits of having a well-managed orchard floor cover between the tree rows include: timely access to the orchard for operations under wet conditions that otherwise would be prevented, as well as better soil structure and water infiltration as a result of the root channels created by the plants that cover the ground (resident vegetation or planted cover crop). Improved water infiltration reduces the risk of off-site movement of pesticides, soil compaction, and the potential for erosion. Resident Vegetation Resident orchard-floor vegetation has several benefits, but the vegetation should not be allowed to invade tree rows. Not all resident plants are desirable growing in the orchard floor; certain difficult-to-control plants can result in major problems. An example is hairy fleabane, which is not readily controlled with the preemergence herbicides that are registered for nectarine plantings and is only susceptible to postemergence sprays when small. It is a prolific producer of windborne seeds that allow it to quickly invade tree rows. Other plants that should be avoided as resident vegetation, such as burclover, curly dock, mustards and certain clovers, can host insect and mite pests, such as lygus, Calocoris spp., thrips, and spider mites. IRRIGATION SYSTEM CONSIDERATIONS Design weed management programs so that they fit your irrigation system. In furrow and basin flood systems with raised berms, the dissipation of preemergence herbicides is slow because the irrigation water does not come in contact with the herbicide. Dissipation is increased in sprinkler, microsprinkler, and drip-irrigated orchards where the irrigation water contacts the herbicide. Irrigation type is an important consideration in selecting preemergence herbicides to prevent tree injury. Certain soil-residual herbicides, such as norflurazon, and simazine, have been found to leach in sandy-type soils that are irrigated frequently with low-volume sprinkler, mist, or drip irrigation. Under these conditions, they can leach into the tree root zone and cause injury and possibly leach into groundwater, causing contamination. Using these herbicides in orchards irrigated with furrow or basin flood irrigation would help reduce the likelihood of leaching and potential tree injury. Weed control provided by the preemergence herbicides breaks down sooner around sprinklers or emitters when compared to the rest of the orchard. These areas require additional weed control measures, such as a postemergence herbicide or hand hoeing. The use of a sensor-controlled sprayer that applies herbicides only to the areas where weeds are growing may be a good choice, because it can reduce herbicide use by more than 50% when compared to a treatment to the entire orchard. SOIL TYPE CONSIDERATIONS Soil type is an important consideration when selecting an orchard weed management strategy. Sandy loam to loamy sand soils require less herbicide for effective weed control than clay loam soils. Preemergence herbicide labels have specific application rates for different soil textures. Applying the suggested rate of herbicide for a clay loam soil to loamy sand not only wastes herbicide but may also cause crop injury.



Because equipment moves easily through loam and loamy sand soils, the timing of cultivation is more flexible than on soils high in clay. Lighter soils are also generally easier to access for spraying and other operations during wet conditions than are heavier soils. WEED MANAGEMENT BEFORE PLANTING It is easier and cheaper to control perennial weeds before planting the orchard because there is a better selection of treatment options available when the ground is fallow. Annual weeds are best controlled before they set seed by mowing, discing, or using herbicides. Established weeds can be controlled either chemically or mechanically. A good time to control perennial weeds such as bermudagrass and field bindweed is in the late summer or early fall. Apply glyphosate when the weeds are at about 20 to 30% flowering (if done after this, seed may have already developed in some flowers). For perennial grasses (johnsongrass or dallisgrass) or nutsedge, apply glyphosate when these weeds are actively growing and then cultivate 2 weeks later. For glyphosate to work properly, the plants must not be under severe water stress. Many underground plant structures can be controlled by cultivation alone. A spring tooth harrow is especially effective. This operation brings root and reproductive structures to the surface and causes them to desiccate. For this system to work, the soil must be dry. Not all weeds are created equally: purple nutsedge is harder to control with desiccation than is yellow nutsedge. If this operation is done incorrectly or at the wrong time, cultivation can actually spread perennial weeds. Cultivating with a soil-inverting plow so that seed is buried in the soil profile and desiccates or rots can effectively control many annual weeds. Deep plowing of nutsedge can provide suppression for 6 to 8 weeks. This method is not effective for long-term control of purple nutsedge because the plants can emerge from soil depths of 18 inches, or more. Grading the Orchard Grade a new orchard site to ensure even drainage and eliminate low spots that promote perennial weed growth. Proper drainage prevents formation of wet areas within the tree row. Constant wetting accelerates the dissipation of herbicides, which may also lead to weed growth. Preparing Tree Rows Before planting, a preemergence herbicide such as trifluralin can be incorporated into the area designated as the tree row. Tree injury may result if the treated soil is placed around the roots at planting. When planting, place untreated soil directly around the roots and then cover them with a surface layer of treated soil. Maintain a weed-free strip that is at least 30 inches from trunk on each side of the tree to prevent weeds from competing with the developing tree. If planting holes are dug with an auger, use glyphosate before planting, and apply a preemergence herbicide once the trees have settled into the soil. WEED MANAGEMENT IN NEWLY PLANTED ORCHARDS Once the trees are planted, disturb the soil as little as possible in orchards that have been treated with a preemergence herbicide. In orchards that are to be furrow irrigated, establish one or two narrow furrows along the planted trees. Perennial grasses can be controlled with clethodim (Select Max), fluazifop-P-butyl (Fusilade), or sethoxydim (Poast). Glyphosate can be used to suppress nutsedges and perennial broadleaf weeds. Avoid spraying nectarine foliage or trunks with glyphosate. Plastic-coated wrappers may help to protect trunks from contact with herbicides, but there is no guarantee that injury will not occur. During tree establishment regular preemergence and postemergence treatments will remove much of the competition from weeds and facilitate irrigation and other cultural practices. Weeds will need to be controlled if herbicides were not applied before the trees were planted. Cross-discing (cultivation both within and across the tree row) is an alternative to herbicide use, but care must be taken not to injure tree roots when discing near trees or suckering can result. This may cause problems in the future if herbicides will be used to control weeds in the tree row. Additional control measures (hand hoeing or spot treatment with herbicides) will be needed for weeds growing adjacent to the trees that are not controlled with tillage operations.



WEED MANAGEMENT IN ESTABLISHED ORCHARDS Vegetation (either resident vegetation or cover crop) can be maintained in the orchard middles and managed by mechanical or chemical mowing (i.e., applying low rates of a postemergence herbicide to reduce plant growth). Chemical mowing can be effective but may contribute to resistance with some weed species. Using a ringroller to press down the vegetation of a nearly mature mulch cover crop is an alternative to mowing. This accelerates the senescence process while allowing some seeds to mature. Leaving the mulch intact blocks light and may prevent weed seeds from germinating. In early spring, mow cover crops or resident vegetation to reduce the risk of spring frost damage. Preemergence and postemergence herbicides are common management tools used within the tree row. Most preemergence herbicides should be applied onto the soil just before a light (¼ inch) irrigation or rainfall to be incorporated into the soil. Do not apply the herbicide if a heavy rain (more than ½ inch in a short period) is anticipated. Check the pesticide label for specific application details. Some preemergence herbicides can provide control for up to a year, depending on their solubility, adsorption to soil, weed species present, dosage applied, and the amount of rainfall or irrigation that occurs. Herbicide leaching is greater on sandy than on clay soils. Prolonged, moist conditions during winter, in furrow bottoms, or around low-volume emitters during irrigation favor breakdown and leaching of herbicides. Most preemergence herbicides do not last throughout the season and do not control all weeds. The application of postemergence herbicides is usually necessary to effectively manage weeds in the orchard. Postemergence herbicides are used on established weeds. They act by contact or by translocation throughout the plant. Contact herbicides, such as paraquat, kill only those parts of the plant that they come in contact with. Good spray coverage and wetting to spread the herbicide are essential. A single application can kill susceptible annual weeds. Retreatment will be necessary if more seeds germinate. Perennial plants that regrow from underground roots or other underground structures will need to be re-treated. If applied at the correct timing, systemic herbicides such as glyphosate will move into the plant and be translocated to the underground portions of the plant and kill them. Glyphosate will not translocate into mature nutsedge tubers. For optimum control of nutsedge, treat before the 5-leaf stage. Repeat applications are necessary. Complete coverage with translocated herbicides is not essential but may improve control. Complete control of established perennials is often difficult, because root structures are often much more extensive than the top growth.


(6/10) Weed Management in Organic Orchards 94 Online with photos at http://www.ipm.ucanr.edu/PMG/selectnewpest.nectarine.html

WEED MANAGEMENT IN ORGANIC ORCHARDS (6/10) Weed control in organically managed orchards requires special attention to preventing weed problems before they start. Any method that reduces the amount of weed seed in the orchard will diminish weed populations over time. Controlling existing weeds before they go to seed is one of the best ways to prevent weed problems. The first step in developing a weed management program is to identify the weeds infesting the orchard or planting site. Becoming familiar with each weed's growth and reproductive habits will help you choose the most effective management options. (See the weed photos linked to the weeds in the list of COMMON AND SCIENTIFIC NAMES OF WEEDS.) Transitioning mature, full-canopied trees to organic production will require less intensive weed management than starting a new organic orchard. Mature, shady orchards often have limited weed growth while weeds in newly planted orchards more effectively compete with trees. WEED MANAGEMENT BEFORE PLANTING The season before trees are planted is a critical period for weed management. It is important that young trees become established with little or no competition from weeds. Weeds can be effectively managed at this time by cultivation and soil solarization. Cultivation Cultivation followed by irrigation to germinate new weeds, followed by cultivation again to kill weed seedlings, is an especially effective weed control method to use before planting trees. Frequent cultivation lowers weed seed populations in the soil, thus reducing weed growth. At least two cycles of cultivation and irrigation, followed by a shallow cultivation are needed for a marked reduction in weed seedlings. This method is not effective for the control of established perennial weeds. If the site is not already certified organic, herbicides can be very helpful in ridding the area of hard-to-control perennials and can be used until the transition time to organic begins. Cultivation when the soil is very dry is an effective method to control perennial grasses such as bermudagrass and johnsongrass. Cultivation cuts the rhizomes into small pieces so they can dry out. Rework the soil frequently with a spring tooth harrow to pull new rhizomes to the surface to dry out. If the soil is irrigated, or rain occurs before total control of the perennial plant is achieved, the rhizome pieces will begin to grow and the effectiveness of this practice is greatly reduced. Working the soil when wet can increase the population of perennial weeds, because each piece of cut rhizome can root and develop into a new plant. Field bindweed growth can be reduced for up to 2 years by deep plowing or using a reclamation blade (a large V-shaped blade) to cut the roots at a depth of 16 to 18 inches in dry soil. Nutsedge infestations can be reduced by deep plowing with large moldboard plows that bury the nutlets to a depth of at least 12 inches. Seedlings of many perennials can be controlled by repeated cultivation. Soil Solarization Soil solarization can significantly reduce weed populations in the planned tree rows. Soil solarization traps the sun's energy beneath a layer of clear plastic. This process can increase the temperature in the top foot of soil to levels lethal to many weed seedlings and vegetative structures of perennial weeds. Solarization will not control perennial weeds as well as it does annuals. Seedlings of bermudagrass, johnsongrass, and field bindweed are controlled, but mature plants are not. Yellow nutsedge is partially controlled while purple nutsedge is not significantly affected. Preparing a smooth seed bed so that the plastic can lie as close as possible to the soil surface is imperative for effective soil solarization and can be accomplished by first discing the soil to break up clods and then rolling or rotating to smooth the soil. Remove any materials such as rocks, sticks, or weeds that will puncture or raise the plastic sheets. Irrigate before or after applying the plastic. Wet soils hold and conduct heat better than dry soil. Seeds that have begun the process of germination by imbibing water are easier to kill than hard seeds. Cover the soil with plastic as soon as possible after irrigating, allowing the soil to dry somewhat to avoid compaction by heavy equipment. It is possible to irrigate after laying the plastic by installing the drip system or the microsprinkler line, using only



the spaghetti tubing, before planting. Another option is to furrow irrigation under the plastic. If the entire site is irrigated, weed growth will occur in the untarped centers during the solarization process and will be difficult to control without disturbing the plastic. Use clear plastic that is 1.5 to 2 mils thick and impregnated with UV inhibitors to prevent premature breakdown. Contact plastic suppliers well in advance so they can formulate plastic tailored to your needs. Cover the area designated as the tree row with plastic from 6- to 10-feet wide, depending on the middles management program you have chosen for the orchard. Bury the plastic on all sides to create a seal on the soil and help prevent the plastic from being blown away by wind. Machines are available that lay down the plastic and automate this otherwise labor-intensive process. In the Central Valley, the plastic should be in place from June through August and can remain in place until planting begins. Solarization may not be as effective in cooler coastal areas. In these areas, apply plastic in August and September, or May and June. Cultivate solarized soil less than 3 inches deep to avoid bringing viable weed seeds to the surface where they germinate. Black plastic suppresses weed seed germination but will not heat the soil sufficiently for solarization. Plastic mulches may not be successful in suppressing species like nutsedge. All plastic should be removed before planting. WEED MANAGEMENT AFTER PLANTING Tree-row Management Mulches can be used to help manage weeds in organic orchards in the years before the orchard bears fruit (nonbearing). The mulch works by blocking light preventing weed germination and growth. Many materials can be used as mulch: municipal yard waste, wood chips, straw, hay, sawdust, newspaper, and others. To be effective, mulches must block all light to the weeds, and materials vary in the depth necessary to accomplish this. A good rule is: the larger or looser that the mulch pieces are, the deeper the mulch should be. Organic mulches must be maintained in a layer at least 4 inches thick. Once the trees are established, weeds in the middles of organic orchards are commonly managed with cover crops or mowing resident vegetation while weeds in the tree row can be managed with a variety of strategies. Weeds in the tree row maybe managed with in-row cultivation, cross discing, cross mowing, hand hoeing, flaming, organically acceptable herbicides, mulches, or animals. The choice depends on cost, tree spacing, the use of berms, and the type of irrigation system. In-row Cultivation In-row cultivators are equipped with a sensor or trigger mechanism that pivots the cutting arm around the tree to avoid injury. Several companies make cultivation equipment; those that have performed well include equipment from Bezzerides, Kimco, and L&H Manufacturing. Sprinkler-irrigated orchards require extra precautions to ensure proper operation of the trigger mechanism on the cultivator so that it moves away from the sprinkler head in the same way as it does for the tree. Furrow-irrigated orchards are amenable to in-row cultivation. To prevent damage to irrigation equipment, microsprinkler irrigation lines and emitters can be suspended in the trees or on stakes with the emitters positioned upside down, and drip lines may be buried. Flaming Flaming can effectively manage in-row weeds that are smaller than eight leaves. Grasses will eventually become the dominant weeds when flaming is used repeatedly because their growing points are at or below ground level. Flaming will suppress but not control perennial weeds. To avoid injury to the cambium layer of the tree, protect the trunks of young trees from flamers. Keep flamers away from plastic irrigation tubing. Do not flame in orchards that have a lot of dried vegetation to avoid fires that may injure trees, irrigations systems, or spread and get out of control. Herbicides Organically certified herbicides are available for use; these materials are generally costly and tend to be much less effective than conventional herbicides. Make sure that the herbicides used are accepted by your organic licensing organization and are registered, or exempted by your state pesticide regulator. As with any contact herbicides, good coverage is essential. Repeat applications will be necessary to control newly emerged weeds. An organically acceptable surfactant can be used to improve efficacy. Avoid spraying nectarine foliage because the herbicides will affect any green tissue.



Animals Sheep can used for weed control in organic orchards and can be very effective in controlling weeds. Their effectiveness depends on several factors, among them the amount of feed available (cover crop and weeds), and the density (number per acre) of sheep used. Goats are grazers and are often used to control the brush around orchards. If goats are used in the orchard, they must be carefully managed to avoid damage to the trees. Geese can also be used to manage grass weeds in orchards. Geese prefer grass species and will eat other weeds and crops only after the grasses are gone. They have a particular preference for the rhizomes of two especially troublesome orchard weeds: johnsongrass and bermudagrass. If confined, will dig the rhizomes up and eat them. Generally, four geese per acre are needed. Consult the following Web site for further information on geese: http://www.metzerfarms.com/UsingWeederGeese.cfm. In most cases all animals used in orchards will require some form of protection from predators (dogs, coyotes, etc.). Consult local statutes to determine if or when animals must be removed from the orchard before harvest. Management Between Tree Rows Consider planting a cover crop in the area between tree rows. Resident vegetation does not usually produce uniform growth. Planted cover crops generally compete better with invasive weeds and thus reduce weed infestations in the orchards over time. Resident vegetation often includes weed species that grow into the tree row. Care must be taken to adjust watering regimes to account for the increased use of water by the cover crop so that it does not compete with trees for available water. Cover crops in dry land orchards should be plowed under in spring before the trees become water stressed. An annual cover crop that reseeds itself will compete against weeds and reduce the potential for weed problems in the future. Plant the cover crops in nectarine soon after harvest, before leaves fall and rainfall, or irrigation water, is available to provide for good germination and seedling growth. Newly established cover crops may be seriously damaged by fall and winter orchard traffic during operations such as pruning, brush removal, and spraying. In orchards where these operations are planned, cover crops may be seeded in alternate middles and these operations carried out in the nonseeded middles. Alternatively, cover crops can be planted in years when these operations are not planned for the orchard. Mow tall cover crops once before bloom to minimize frost damage; the cover crop will regrow and flower later in the season. If mowing can be avoided, the cover crop will be most competitive. An exception is subclover cover crop, which will compete with taller weeds if mowed before mid-March. The cover crop should be mowed or ring-rolled after most species have produced seed. Ring-rolling will create a surface mulch that will shade the soil, preventing many weed seeds from germinating.


(6/10) Special Weed Problems 97 Online with photos at http://www.ipm.ucanr.edu/PMG/selectnewpest.nectarine.html

SPECIAL WEED PROBLEMS (6/10) BERMUDAGRASS Bermudagrass is a vigorous perennial weed that grows in the spring and summer. It is propagated by seed and an extensive rhizome and stolon system that is often spread during cultivation. Bermudagrass competes aggressively with trees for moisture and nutrients. Seedlings can be controlled with preemergence herbicides. Immediately spot treat any areas of bermudagrass that develop in an orchard or localized area with a postemergence herbicide such as glyphosate (Roundup). Take care not to let any herbicide drift onto the trees. Bermudagrass frequently becomes a problem in mowed orchards because mowing increases the amount of light that the stolons receive, thus stimulating their growth. In organic orchards, geese have been used to control grasses, including bermudagrass. If confined to an area containing bermudagrass, geese will dig up the rhizomes and completely consume the plant. COMMON PURSLANE Common purslane is a prostrate summer annual that reproduces from seed that germinate in April to early May. Mature common purslane has fleshy stems that can root and continue to grow after cultivation or mowing if moisture is present. This weed predominates in sunny areas of the orchard, especially if low rates of translocated herbicides (e.g., glyphosate) are used as preharvest sprays. If problems develop with this weed, use higher rates of glyphosate to control it. Oryzalin (Surflan) at 1 qt/acre applied with glyphosate in April between the tree rows (middles) can provide season long control. DALLISGRASS Dallisgrass is a common perennial grass found in orchards. It can be highly invasive in newly planted orchards. Dallisgrass seedlings germinate in spring and summer and form new plants on short rhizomes that develop from the original root system. Dallisgrass seedlings can be controlled with cultivation or with preemergence herbicides. Dallisgrass has a clumpy growth habit that gives it a bunchgrass appearance. Like bermudagrass, it tends to become dominant in mowed areas because mowing stimulates seed set. It also grows in areas with standing water. The plants are heavy seed producers. Treatment with glyphosate has been successful in controlling dallisgrass infestations. For organic orchards, consider using geese, which eat grasses preferentially. FIELD BINDWEED Field bindweed is a vigorous perennial weed that grows from rhizomes, an extensive sprouting root system, or seed that can survive for up to 30 years in the soil. Because of the seed's longevity in the soil, it is critical to control these plants before they can produce seed. Seedling field bindweed is controlled with cultivation, but mature plants may spread from stem or root sections that are cut during this operation. If field bindweed appears in or around the orchard, spot treat with high label rates of glyphosate. In organic orchards, cultivation at 2- to 3-week intervals during the growing season may eventually deplete the root system and starve plants growing on lighter soils. HAIRY FLEABANE Hairy fleabane is an annual plant that normally emerges in February, but it can emerge as early as October and continue germinating throughout the winter, if temperatures are warmer than average. This plant can withstand several mowings and still produce seed. In addition, it can interfere with moving sprinkler and drip irrigation lines. Paraquat and glyphosate both can control this species when it is small, but once plants bolt (sending up flowering stalks), they will not control it. Tank-mixing glyphosate plus 2,4-D provides excellent control when these weeds are small. Be sure to follow all label and permit restrictions when using 2,4-D to avoid crop injury. A close relative, horseweed, has developed resistance to glyphosate in many parts of the Unites States. Thus, it is critical to monitor control efforts and follow up with hand hoeing to prevent escape of any plants that might be resistant. HORSEWEED Horseweed is a common weed in California orchards, cultivated fields, and disturbed areas. This annual weed has a woody stalk and can grow up to 10 feet tall. If not controlled, it can obstruct harvesting practices. Like hairy


(6/10) Special Weed Problems 98 Online with photos at http://www.ipm.ucanr.edu/PMG/selectnewpest.nectarine.html

fleabane, this weed can withstand mowing and interfere with moving sprinkler and drip irrigation lines. Paraquat and glyphosate both can control this species when it is small, but once plants bolt (sending up flowering stalks), they will not control it. In some areas, horseweed has developed resistance to glyphosate. Thus, it is critical to monitor control efforts and follow up with hand hoeing to prevent escape of any plants that might be resistant. Tank-mixing glyphosate plus 2,4-D provides excellent control when these weeds are small as does adding ammonium sulfate at 10 to 15 lb/acre or citric acid to glyphosate. Be careful to follow all labels and permit restrictions when using 2,4-D to avoid crop injury. JOHNSONGRASS Johnsongrass can be a serious problem, especially in young nectarine orchards. It can be controlled by repeated tillage during the dry summer months, but the soil must be dry or the rhizome buds may sprout. Repeated applications of postemergence herbicides such as clethodim (Select Max), fluazifop-P-butyl (Fusilade), glyphosate (Roundup), sethoxydim (Poast), or others will often be required for control of johnsongrass. Johnsongrass is most effectively controlled by selective grass herbicides (clethodim, fluazifop-P-butyl, sethoxydim) when it is between 8 and 18 inches tall. A second application is usually required to prevent rhizome production and limit the chance of regrowth. Apply glyphosate when johnsongrass is actively growing and between 12 and 24 inches tall. Geese are also effective at controlling johnsongrass in organic orchards. In new plantings, trifluralin (Treflan) or norflurazon (Solicam) will control seedling johnsongrass but not established johnsongrass plants. RYEGRASSES Ryegrasses are annual winter grasses that are common throughout California. In 1998, two orchard sites were identified as having glyphosate-resistant ryegrass populations. More recent surveys have observed that glyphosate-resistant ryegrass is now in numerous orchards in Northern California and at least some orchards in the San Joaquin Valley. It is estimated that glyphosate-resistant ryegrass now occupies over 5,000 acres in California. The potential risk for the development of herbicide resistance is greatest when the same herbicide is used repeatedly, as often is done in orchards. To prevent the development of resistance use a variety of weed control strategies, including cultural practices and alternating herbicides with different modes of action. Failure to do so can result in the rapid loss of herbicides as a pest management tool, although cultivation remains an option. If resistant populations are observed, avoid moving resistant weeds from one field to another by cleaning equipment before moving out of a field with known herbicide resistant weeds. Consider scheduling known resistant fields as the last ones to be planted, harvested, etc. Paraquat is effective when applied to very small seedlings, and two applications of selected grass herbicides (e.g. Fusilade, Poast, and Select Max) are effective in ryegrass control. SPRANGLETOP Mexican sprangletop is spreading at an increasing pace in San Joaquin Valley orchards, field edges, and ditch banks. This is especially true where preemergence herbicide applications have been stopped, and glyphosate has become the dominant part of the weed control program. Sprangletop can be controlled by postemergence applications of glyphosate when weeds are small. For complete control, repeat applications are necessary within 14 to 21 days. Preemergence control can be achieved with several herbicides including oryzalin (Surflan), pendimethalin (Prowl), and pronamide (Kerb). These herbicides may lose effectiveness in late summer, depending on the rate applied, and not control sprangletop that emerges in fall. NUTSEDGE Yellow and purple nutsedges are perennial weeds that reproduce from underground tubers that survive for 2 to 5 years in the soil. The tubers are easily spread by cultivation equipment. Each tuber contains several buds that are capable of producing plants. One or two buds germinate to form new plants; however, if destroyed by cultivation or an herbicide, then a new bud is activated. If a nutsedge infestation develops in established orchards, spot-treat it with glyphosate. For best results, treat young plants before more than 5 leaves have formed. This is the approximate stage in which they begin to produce tubers. Repeat treatments are usually necessary to control late-germinating plants. Where nutsedge is already well established, treat with glyphosate every 21 to 28 days during the season as new growth flushes emerge. Nutsedge can be suppressed by a preemergence application of norflurazon (Solicam) or thiazopyr (Visor); thiazopyr is registered for use in nonbearing orchards only.


(6/10) Common and Scientific Names of Weeds 99 Online with photos at http://www.ipm.ucanr.edu/PMG/selectnewpest.nectarine.html

COMMON and SCIENTIFIC NAMES OF WEEDS (6/10)

Common Names Scientific Names Barley, hare Hordeum leporinum Barnyardgrass Echinochloa crus-galli Bermudagrass Cynodon dactylon Bindweed, field Convolvulus arvensis Blackberries, wild Rubus spp. Bluegrass, annual Poa annua Brome, downy Bromus tectorum Brome, ripgut Bromus diandrus Burclover, California Medicago polymorpha Canarygrass Phalaris spp. Chickweed, common Stellaria media Clovers Trifolium spp. Crabgrasses Digitaria spp. Cudweeds Gnaphalium spp. Dallisgrass Paspalum dilatatum Dandelion Taraxacum officinale Dock, curly Rumex crispus Fescues Festuca spp. Fiddlenecks Amsinckia spp. Filarees Erodium spp. Fleabane, hairy Conyza bonariensis Fluvellins Kickxia spp. Foxtails Setaria spp. Goosefoot, nettleleaf Chenopodium murale Groundsel, common Senecio vulgaris Henbit Lamium amplexicaule Horseweed Conyza Canadensis Johnsongrass Sorghum halepense Junglerice Echinochloa colona Knotweed, common Polygonum arenastrum Lambsquarters, common Chenopodium album Lettuce, miner's Claytonia perfoliata Lettuce, prickly Lactuca serriola Mallow, little (cheeseweed) Malva parviflora Mustards Brassica spp. Nettle, burning Urtica urens Nightshades Solanum spp. Nutsedge, purple Cyperus rotundus Nutsedge, yellow Cyperus esculentus Oat, wild Avena fatua Oxalis Oxalis spp. Pigweeds Amaranthus spp. Pineapple-weed Chamomilla suaveolens Plantain, buckhorn Plantago lanceolata

(Continued next page)


(6/10) Common and Scientific Names of Weeds 100 Online with photos at http://www.ipm.ucanr.edu/PMG/selectnewpest.nectarine.html

Common Names Scientific Names Polypogon, rabbitfoot Polypogon monspeliensis Puncturevine Tribulus terrestris Purslane, common Portulaca oleracea Radish, wild Raphanus raphanistrum Redmaids(desert rockpurslane) Calandrinia ciliata Rocket, London Sisymbrium irio Ryegrasses Lolium spp. Sandburs Cenchrus spp. Shepherd's-purse Capsella bursa-pastoris Sowthistles Sonchus spp. Sprangletops Leptochloa spp. Spurge, spotted Euphorbia (=Chamaesyce) maculata Thistle, Russian Salsola tragus Willowherb, tall annual Epilobium brachycarpum


(6/10) Susceptibility of Winter Weeds to Herbicide Control 101 Online with photos at http://www.ipm.ucanr.edu/PMG/selectnewpest.nectarine.html

SUSCEPTIBILITY OF WINTER WEEDS TO HERBICIDE CONTROL (6/10) Preemergence Postemergence Combinations FLM ISO NOR ORY OXY PEN PRO SIM TRI CAR CLE FLU GLY OXY PAR* SET 2,4D* ORY

OXY GLY1 OXY

ANNUAL WEEDS Barley, hare P N C C P C C C C N C C C P P C N P C Bluegrass, annual C N C C P C C C C N C N C P P N N C C Brome, downy P N C C N C C C C N C P C N P P N P C Brome, ripgut P N C C — C C C C N C P C N P C N P C Burclover, California — P N N C P — C — — — N C P P N — P C Canarygrass P N C C P C C C C N C C C P P C N — C Chickweed, common C C P C N C C — C P N N C N C N P — C Clovers, perennial — P N N P N N C N — N N P P P N P P P Cudweeds C P C N N N N C N — N N C P N N P N C Fiddlenecks C C C C C C C C C C N N C C C N P — C Filarees C C P N C N N C P — N P P C P N P P C Groundsel, common C C P N C N N C N — N N C C C N P C C Henbit C C P P C C C C C — N N C C C N P C C Lettuce, miner's — C C C C — P C C — N N C — C N N — C Mallow, little C P P P C N P N N C N N P C N N N C C Mustards C C P N C N C C N P N N C P C N C P C Nettle, burning C C C P C C P C P C N N N P P N P P P Oat, wild C N P P P P P C P N C C C N P C N P C Pineapple-weed — C P N C N N C N N N N C P P N N — C Polypogon, rabbitfoot — N C C N — — C C N C C C — P C N — C Radish, wild C C P N C N P C N P N N C P P N C P C Redmaids — C C C C C — C C P N N C C C N C C C Rocket, London C C P N C N C C N C N N C C C N C C C Ryegrasses P N C C N C C C C N C C C2 N P C N N C Shepherd's–purse C C P N C C C C N P N N C P C N C P C C = control P = partial control N = no Control — = no information CAR = carfentrazone (Shark) GLY = glyphosate (Roundup) OXY = oxyfluorfen (Goal, GoalTender) SET = sethoxydim (Poast) CLE = clethodim (Select Max) ISO = isoxaben (Gallery) PAR = paraquat* (Gramoxone) SIM = simazine (Princep, Caliber) FLM = flumioxazin (Chateau) NOR = norflurazon (Solicam) PEN = pendimethalin (Prowl H2O) TRI = trifluralin (Treflan) FLU = fluazifop-P-butyl (Fusilade) ORY = oryzalin (Surflan) PRO = pronamide (Kerb) 2,4D = 2,4-D* (Orchard Master)

* Permit required from county agricultural commissioner for purchase or use. 1 At rates used for annual weeds, control of perennials is less than expected with high label rates. 2 Some populations in California are known to be resistant.


(6/10) Susceptibility of Spring and Summer Weeds in Nectarines to Herbicide Control 102 Online with photos at http://www.ipm.ucanr.edu/PMG/selectnewpest.nectarine.html

SUSCEPTIBILITY OF SPRING AND SUMMER WEEDS IN NECTARINES TO HERBICIDE CONTROL (6/10) Preemergence Postemergence Combinations FLM ISO NOR ORY OXY PEN PRO SIM TRI CAR CLE FLU GLY OXY PAR* SET 2,4D* ORY

OXY GLY1 OXY

ANNUAL WEEDS Barnyardgrass C N P C P C C P C N C P C N P C N C C Cocklebur — P C N C N N P N P N N C C C N C C C Crabgrasses C N P C N C C N C N C C C P C C N C C Cudweeds C P C N N N N C N N N N C P N N P P C Fleabane, hairy P P P N P N N C N N N N C P P N P P C Foxtails C N C C N C C C C — C C C N C C N C C Filarees C C P N C N N C P C N P P C P N P C C Goosefoot, nettleleaf C C C C C P C C C — N N C P C N C C C Goosegrass C N C C N C C C C N C C P N P — N — C Groundcherry C C C P C N C C N C N N C C C N C C C Horseweed C P P N P N N C N N N N C P P N C P C Junglerice C N C C P C P P C N C P C N P C N C C Knotweed, common — C P C P C C C C — N N P P C N P C P Lambsquarters, common C C P C C C C C C C N N C C C N C C C Lettuce, prickly P C P N C N N C N P N N C C P N C C C Lovegrass C N P C P C C P C N C C C N P C N C C Nightshades C C C N C N C C N P N N C C C N C C C Pigweeds C C P C C C N C C C N N C C C N C C C Puncturevine C P C P C C N P P — N N C P C N C P C Purslane, common C C P C C C C C C P N N P C C N C C P Sandburs — N P C N C — P C N C P C N P P N P C Sowthistles P C P N C N P C N N N N C C P N C C C Sprangletops P N P C N C C N P N C P C P P P N — C Spurge, spotted — C P P P C P C N — N N C N C N C P C Starthistle, yellow — — — N C N N C N N N N C N C N C — C Thistle, Russian C P C P P P P C P C N N C P C N P P C Willowherb, tall annual P P P P C — — N — — N N P N N N C C P Witchgrass P N C P C C C C C N C C C N N C N C C PERENNIAL WEEDS Bermudagrass (Se) N N C C N C N P N N C C C N P C N C C Bermudagrass (Pr) N N P N N N N N N N P P P N N P N N P Bindweed, field (Se) — C P P N P P C P C N N C N P N C N C Bindweed, field (Pr) — C N N N N P N P P N N C N N N P N P Blackberries, wild N — N N N N — N N — N N C N N N P — C Dallisgrass (Se) — N N C N C C C C N C C C N N C N P C Dallisgrass (Pr) N N N N N N N N N N P P P N N P N N P Dandelion (Se) — P N P N N N C N — N N C N P N C — C Dandelion (Pr) N N N N N N — N N — N N P N N N C — P Dock, curly (Se) — C N P C C C C C — N N P C C P C C C Dock, curly (Pr) — N N N N N N N N — N N P N N P P N P


(6/10) Susceptibility of Spring and Summer Weeds in Nectarines to Herbicide Control 103 Online with photos at http://www.ipm.ucanr.edu/PMG/selectnewpest.nectarine.html

Preemergence Postemergence Combinations FLM ISO NOR ORY OXY PEN PRO SIM TRI CAR CLE FLU GLY OXY PAR* SET 2,4D* ORY

OXY GLY1 OXY

Fescues P N C C P — C — C N P P C N P P N C C Fluvellins N — — — — — — — — — N N P — — N — — P Johnsongrass (Se) C N C C N C C N C N C C C N C C N C C Johnsongrass (Pr) N N P N N N N N N N C C P N N P N N P Nutsedge, yellow N N P N N N N N N N N N C N N N N N P Nutsedge, purple N N P N N N N N N N N N C N N N N N P Oxalis N C — P C P — C P — N N C — P N P — C Plantain, buckhorn (Se) — P — — — — N C — — N N C — C N C — C Plantain, buckhorn (Pr) — P N N N N N N N — N N P — N N P — P Se = seedling Pr = perennial plant C = control P = partial control N = no control — = no information CAR = carfentrazone (Shark) GLY = glyphosate (Roundup) OXY = oxyfluorfen (GoalTender) SET = sethoxydim (Poast) CLE = clethodim (Select Max) ISO = isoxaben (Gallery) PAR = paraquat* (Gramoxone) SIM = simazine (Princep, Caliber) FLU = fluazifop-P-butyl (Fusilade) NOR = norflurazon (Solicam) PEN = pendimethalin (Prowl H2O) TRI = trifluralin (Treflan) FLM =flumioxazin (Chateau) ORY = oryzalin (Surflan) PRO = pronamide (Kerb) 2,4D = 2,4-D* (Orchard Master)


(8/15) Herbicide Treatment Table 104 Online with photos at http://www.ipm.ucanr.edu/PMG/selectnewpest.nectarine.html

HERBICIDE TREATMENT TABLE (8/15)


Amount per acre

REI‡ (hours)

PHI‡ (days)

The following are listed alphabetically. When choosing a pesticide, consider information relating to environmental impact, resistance management, the pesticide's properties, and application timing. Not all registered pesticides are listed. Always read the label of the product being used.

PREPLANT Preemergence (before weeds germinate) A. PENDIMETHALIN 2–3.96 lb a.i. (Prowl H2O) 2-6.3 qt 24 NA WSSA MODE-OF-ACTION GROUP NUMBER1: 3 COMMENTS: Preemergence, selective herbicide for annual grasses and some broadleaves. Apply to soil in 10

gal/acre or more before planting and incorporate mechanically 2.5 inches deep. Use untreated soil to fill in around tree roots.

B. TRIFLURALIN 0.5–1 lb a.i. 12 NA (Treflan HFP) WSSA MODE-OF-ACTION GROUP NUMBER1: 3 COMMENTS: Broadcast preplant in 5 to 40 gallons of water per acre. Trifluralin must be incorporated immediately

after application to avoid loss of activity. Plant tree roots below treated soil. Do not place treated soil near roots during planting. Controls many annuals and is helpful in suppressing perennial weeds. Residual period: 2–12 months.

Postemergence (after weeds emerge) A. GLYPHOSATE (Roundup PowerMax) 0.387–3.713 lb a.e. 4 17 WSSA MODE-OF-ACTION GROUP NUMBER1: 9 COMMENTS: Apply with a controlled applicator or with low-pressure flat fan nozzles. For annual weed control, use

1 lb/acre in 3–10 gal water. Ammonium sulfate can also be added (1 to 2% by weight or 8.5 to 17 lbs per 100 gallon of water) to the spray solution to significantly improve control in areas with hard water. It is important to add the ammonium sulfate to the water before adding the herbicide. Apply to young annuals or vigorously growing perennials in flowering stage. Some perennials require the 4lb/acre rate for control. May be used on young weeds in the planting row followed by planting into the dead weeds. As a result of the no-till effect, new weeds usually do not establish for a month or more. Do not use more than 9.625 lb a.i./acre per year.

NEWLY PLANTED ORCHARDS (NONBEARING TREES) Preemergence A. FLUMIOXAZIN (Chateau SW) 0.188-0.376 lb a.i. 12 60 WSSA MODE-OF-ACTION GROUP NUMBER1: 14 COMMENTS: Provides effective control of many annual grasses and broadleaves, including horseweed. Apply in 10

or more gal water/acre to soil under trees when completely dormant. Do not apply on newly planted trees unless soil is firm and there are no cracks in soil around base of trees. Best control is achieved when irrigation or rainfall occurs within 21 days. Can be mixed with other pre- or postemergence herbicides. It will not provide adequate control of emerged weeds, unless mixed with a postemergence herbicide. Residual period: 3–6 months




Amount per acre

REI‡ (hours)

PHI‡ (days)

B. ISOXABEN (Gallery T&V) 0.5–0.9975 lb a.i.

(0.66–1.33 lb product) 12 365

(Trellis SC) 0.52–1.008 lb a.i. (16–31 fl oz)

12 365

WSSA MODE-OF-ACTION GROUP NUMBER1: 21 COMMENTS: Wait until soil has settled around newly planted trees before applying. Controls broadleaf weeds only

before they have germinated; will not control emerged weeds. If weeds are emerged, lightly cultivate or add a postemergence herbicide. Requires incorporation for activation, either by light cultivation (1 to 2 inches) or rainfall (minimum of 0.5 inches) within 21 days after application. Sprinkler or flood irrigation can also be used for incorporation. Apply in at least 10 gal/acre of water.

C. ORYZALIN (Surflan, Oryzalin 4 A.S.) 2–6 lb a.i. 24 0 WSSA MODE-OF-ACTION GROUP NUMBER1: 3 COMMENTS: Preemergence selective herbicide for annual grasses and some broadleaves. Apply to the soil surface in

20–40 gal water/acre. If rain does not occur within 21 days, sprinkle irrigate with 0.5–2 inches of water. May be combined with a postemergence herbicide if weeds are present. Most effect on annual grasses and numerous broadleaf annuals. Very safe for young or newly planted trees and on sandy or sandy loam soils. Used to maintain control in strips down the row. The higher rates give the longest soil residual. Usually used at 4 lb a.i./acre. Residual period: 4–10 months.

D. PENDIMETHALIN (Prowl H2O) 2–3.96 lb a.i. 24 NA (Prowl 3.3EC) 2–3.96 lb a.i. 24 NA WSSA MODE-OF-ACTION GROUP NUMBER1: 3 COMMENTS: For use on dormant nonbearing trees only. Selective preemergence herbicide for annual grasses and

some broadleaves. Apply in 10 or more gal water/acre to soil under trees. Do not apply on newly planted trees unless soil is firm and there are no cracks in soil around base of trees. Best control is achieved when irrigation or rainfall occurs within 7 days. Will not control emerged weeds. Residual period: 4–10 months

E. TRIFLURALIN (Treflan HFP) See label 12 0 WSSA MODE-OF-ACTION GROUP NUMBER1: 3 COMMENTS: Preemergence selective herbicide for annual grasses and some broadleaves. Apply prebloom by ground

as a directed spray and mechanically incorporate, taking care not to injure the trees with the incorporation. Must be incorporated immediately after application to avoid loss of activity. Used on new plantings or established orchards as a strip treatment. Suppresses bermudagrass, johnsongrass, and dallisgrass rhizomes. Only one application per year. Residual period: 2–12 months, depending on rate.

Postemergence A. CARFENTRAZONE (Shark EW) 0.008–0.025 lb a.i. 12 3 day WSSA MODE-OF-ACTION GROUP NUMBER1: 14 COMMENTS: A postemergence, contact herbicide used for quick top kill of most broadleaf weed species. Can be

applied anytime during the season, but if fruit are present, it should either be avoided or applied with extreme care to avoid drift. It can also be used for sucker control. Apply in a minimum of 20 gal water/acre to weeds less than 6 inches tall. Do not exceed 30 psi. Repeat treatments as new growth occurs, but they must be at least 14 days apart. Do not use more than 0.096 lb a.i./acre per season. Use 0.25% volume per volume nonionic surfactant, 1.0% volume per volume of a crop oil concentrate, or a silicone or MSO surfactant.

B. CLETHODIM (Select Max) 0.095–0.12125 lb a.i. 24 365 WSSA MODE-OF-ACTION GROUP NUMBER1: 1 COMMENTS: For use on nonbearing trees only. Do not use in Solano County. Apply to young, nonstressed annual or

perennial grasses. Repeat applications will be required for the control of perennial grasses. Apply in 5 to 40 gal water/acre. Add 0.25% volume per volume nonionic surfactant to the spray solution. Spray pressure should be between 30 and 60 psi, with higher pressures used when weed density is high. Do not apply a broadleaf herbicide within one day following application or reduced grass control may occur. Residual period: less than one month.




Amount per acre

REI‡ (hours)

PHI‡ (days)

C. SETHOXYDIM (Poast) 0.19–0.46 lb a.i. 12 25 days WSSA MODE-OF-ACTION GROUP NUMBER1: 1 COMMENTS: Can be applied to trees at all stages of growth. Apply to young nonstressed annual or perennial

grasses. Repeat applications will be required for the control of perennial grasses. Add 2 pt/acre of a nonphytotoxic crop oil concentrate to the spray solution. Residual period: less than one month.

ESTABLISHED ORCHARDS Preemergence A. FLUMIOXAZIN (Chateau SW) 0.188-0.376 lb a.i. 12 60 WSSA MODE-OF-ACTION GROUP NUMBER1: 14 COMMENTS: Provides effective control of many annual grasses and broadleaves, including horseweed. Apply in 10

or more gal water/acre to soil under trees when completely dormant. Do not apply on newly planted trees unless soil is firm and there are no cracks in soil around base of trees. Best control is achieved when irrigation or rainfall occurs within 21 days. Can be mixed with other pre- or postemergence herbicides. It will not provide adequate control of emerged weeds, unless mixed with a postemergence herbicide. Use allowed under a supplemental label. Residual period: 3–6 months

B. INDAZIFLAM (Alion) 0.045–0.085 lb a.i. 12 14 WSSA MODE-OF-ACTION GROUP NUMBER1: 29 COMMENTS: See label for specific rate and soil considerations. Only use in orchards where trees have been

established at least three years and are exhibiting normal growth and good vigor. See label for restrictions on use around new replants in established orchards.

C. NORFLURAZON* (Solicam DF) 1.97–3.93 lb a.i. 12 60 WSSA MODE-OF-ACTION GROUP NUMBER1: 12 COMMENTS: Can suppress yellow nutsedge or bermudagrass when used year after year. Apply to soil as a directed

spray from fall to early spring under trees established for at least 2 years. If no rainfall occurs within 4 weeks, incorporate with sprinkler or flood irrigation. Remove existing weeds with cultivation or a postemergence herbicide, because it has no postemergence activity. Avoid higher rates on sandy or gravelly soils to prevent injury to trees. Considered to be a ground water contaminant and requires a use permit within Ground Water Protection Areas. Do not use in the Coachella Valley. Apply in 20–100 gal water/acre. Residual period: 6–12 months.

D. ORYZALIN (Surflan, Oryzalin 4 A.S.) 2–6 lb a.i. 24 0 WSSA MODE-OF-ACTION GROUP NUMBER1: 3 COMMENTS: Apply to the soil surface in 20–40 gal water/acre. If rain does not occur within 21 days, sprinkle irrigate

with 0.5–2 inches of water. Most effect on annual grasses and numerous broadleaf annuals. Very safe for sandy or sandy loam soils. Used to maintain control in strips down the row. May be combined with a postemergence herbicide if weeds are present. The higher rates give the longest soil residual. Usually used at 4 lb a.i./acre. Residual period: 4–10 months.

E. OXYFLUORFEN (GoalTender) 0.5–2 lb a.i. 24 See comments WSSA MODE-OF-ACTION GROUP NUMBER1: 14 COMMENTS: For use on dormant trees only. Apply following harvest up to February 15 (February 1 in the Coachella

Valley). Apply by ground one time per season in 40–100 gal water/acre on firm soil. Must not be mechanically disturbed or poor weed control will result. Effective as a pre- and postemergence herbicide. Effective on little mallow (cheeseweed). Useful combined with other postemergence herbicides, such as glyphosate, or in combination with preemergence herbicides, such as oryzalin or simazine,. Check label for use period. Residual period: 4–10 months. Certain formulations emit high amounts of volatile organic compounds (VOCs); use low-VOC formulations.




Amount per acre

REI‡ (hours)

PHI‡ (days)

F. PENDIMETHALIN (Prowl H2O) 2–3.96 lb a.i. 24 NA WSSA MODE-OF-ACTION GROUP NUMBER1: 3 COMMENTS: Selective preemergence herbicide for annual grasses and some broadleaves. Apply in 10 or more gal

water/acre to soil under trees. Do not apply on newly planted trees unless soil is firm and there are no cracks in soil around base of trees. Best control is achieved when irrigation or rainfall occurs within 7 days. Will not control emerged weeds. Residual period: 4–10 months.

G. PRONAMIDE* (Kerb 50-W) 1–4 lb a.i. 24 NA WSSA MODE-OF-ACTION GROUP NUMBER1: 3 COMMENTS: Do not apply to trees less than 1 year old. Selective herbicide for control of winter annual and perennial

grasses. Apply in fall after fruit harvest. Apply in 40-50 gal water/acre to the soil at the base of the trees. Must be applied before weed emergence because it will not control emerged weeds. Rainfall or irrigation is essential after application for effective weed control. Residual period: 4-8 months.

H. RIMSULFURON 0.0625 lb a.i. 4 14 (Matrix FNV) WSSA MODE-OF-ACTION GROUP NUMBER1: 2 COMMENTS: For use on nonbearing and bearing trees. Apply in 10 or more gal water/acre to soil under trees. Apply

only to trees that have been established for one full growing season. Best control is achieved when irrigation or rainfall occurs within 2 weeks after application. When band applications are made, treating 50% or less of an orchard, a second application can be made. Will not control emerged weeds. Residual period: 4–10 months.

I. SIMAZINE* (Princep Caliber 90) 1–1.98 lb a.i. 12 0 WSSA MODE-OF-ACTION GROUP NUMBER1: 5 COMMENTS: Apply to the soil under trees older than 3 years. Make only one application per year. Use the high rate

for heavy soils. Simazine is frequently used in combination with other preemergence herbicides. On light soils, simazine often is used at rates of 0.5-1.0 lb a.i./acre. Do not use on gravel, sand, or loamy sand soils. If irrigation is applied immediately after application, limit water to 0.5 inch. Considered to be a ground water contaminant and requires a use permit within Ground Water Protection Areas. Residual period: 8-12 months.

J. TRIFLURALIN (Treflan HFP) 1–2 lb a.i. 12 0 WSSA MODE-OF-ACTION GROUP NUMBER1: 3 COMMENTS: Preemergence selective herbicide for annual grasses. Apply prebloom by ground as a directed spray

and mechanically incorporate, taking care not to injure the tree. Must be incorporated immediately after application to avoid loss of activity. Frequently used as a strip treatment. Suppresses bermudagrass, johnsongrass, and dallisgrass rhizomes. Only one application per year. Residual period: 2–12 months.

Postemergence A. CARFENTRAZONE (Shark EW) 0.008–0.025 lb a.i. 12 3 day WSSA MODE-OF-ACTION GROUP NUMBER1: 14 COMMENTS: A postemergence, contact herbicide used for quick top kill of most broadleaf weed species. Can be

applied anytime during the season, but if fruit are present, it should either be avoided or applied with extreme care to avoid drift. It can also be used for sucker control. Apply in a minimum of 20 gal water/acre to weeds less than 6 inches tall. Repeat treatments as new growth occurs, but they must be at least 14 days apart. Do not use more than 0.096 lb a.i./acre per season. Use 0.25% volume per volume nonionic surfactant, 1.0% volume per volume of a crop oil concentrate, or a silicone or MSO surfactant.

B. FLUAZIFOP-P-BUTYL (Fusilade DX) 0.125–0.375 lb a.i. 12 14 WSSA MODE-OF-ACTION GROUP NUMBER1: 1 COMMENTS: For control of annual and perennial grass weeds. A crop oil concentrate at 0.5 to 1% volume per volume

or a nonionic surfactant at 0.25 to 0.5% volume per volume must be added to the spray solution. Diammonium phosphate (10-34-0) can also be added to the spray solution to improve control in areas with hard water. Add the diammonium phosphate to the water before adding the herbicide and surfactant. Avoid contact of spray with foliage of trees. Apply in 5-40 gal water, with spray pressures of 30 to 60 psi. Do not apply to grass that is moisture stressed or poor control may result. Apply to johnsongrass when it is between 8 to 18 inches in height. Repeat applications are required for johnsongrass and bermudagrass. Do not graze animals in treated area.




Amount per acre

REI‡ (hours)

PHI‡ (days)

C. GLUFOSINATE (Rely 280) 0.8–1.5 lbs a.i. 12 14 WSSA MODE-OF-ACTION GROUP NUMBER1: 10 COMMENTS: Application rate based on weed size. Only trunks with callused, mature brown bark should be sprayed

unless protected from spray contact by nonporous wraps, grow tubes, or waxed containers. Contact with parts of tree other than mature brown bark can result in serious injury. Do not apply within 300 yards of non-dormant pear trees.

D. GLYPHOSATE (Roundup PowerMax) 0.387–3.713 lb a.e. 4 17 WSSA MODE-OF-ACTION GROUP NUMBER1: 9 COMMENTS: Apply with controlled droplet application or with low-pressure, flat-fan nozzles. For annual weed

control, use 1 lb a.i./acre in 3–10 gal water. Ammonium sulfate can also be added (1 to 2% by weight or 8.5 to 17 lbs per 100 gallon of water) to the spray solution to improve control in areas with hard water. It is important to add the ammonium sulfate to the water before adding the herbicide. For chemical mowing, consult label for exact timing and rates, depending on weed size and species. Apply to young annuals or vigorously growing perennials. Bermudagrass and field bindweed require up to 4 lb a.i./acre rate for control. Persistence is the key for effective control of perennial weeds (i.e. treating every 21 days). Eradication of field bindweed is difficult where roots are deep or tapped into perched water tables. Not effective on some broadleaf weeds at older stages of growth (little mallow and filaree). Avoid drift onto green bark or foliage of tree or injury will result. It is important to monitor treated areas for escaped weeds, as glyphosate resistant weeds have been observed in orchards where glyphosate has been used repeatedly for several years.

E. OXYFLUORFEN (GoalTender) 0.5–2 lb a.i. 24 See comments WSSA MODE-OF-ACTION GROUP NUMBER1: 14 COMMENTS: Dormant application to young (4-leaf-stage) weeds. Effective on little mallow (cheeseweed) and filaree.

Useful combined with glyphosate or oryzalin. May be combined with other postemergence herbicides for specific weeds. Apply following harvest up to February 15 (February 1 in the Coachella Valley). Apply by ground one time per season in 40–100 gal water/acre on firm soil. Must not be mechanically disturbed or poor weed control will result. Effective as a pre-and postemergence herbicide. Residual period: 4–10 months. Certain formulations emit high amounts of volatile organic compounds (VOCs); use low-VOC formulations.

F. PARAQUAT* (Gramoxone SL) 0.625–1 lb a.i. 24 28 WSSA MODE-OF-ACTION GROUP NUMBER1: 22 COMMENTS: Nonselective postemergence, contact herbicide used for quick top kill of most weed species. Provides

temporary burn down only. Less effective against perennials that will regrow (bermudagrass, dallisgrass, johnsongrass and field bindweed). Most effective when used in late winter or early spring on small annual grass species in combination with preemergence herbicides. Apply in 10–60 gal water/acre to young weeds. Use 0.25% volume per volume nonionic surfactant or 1.0% volume per volume of a crop oil concentrate. Repeat treatment as new growth occurs. Do not exceed 3 applications per season.

G. SETHOXYDIM (Poast) 0.19–0.46 lb a.i. 12 25 days WSSA MODE-OF-ACTION GROUP NUMBER1: 1 COMMENTS: Can be applied to trees at all stages of growth. Apply to young nonstressed annual or perennial

grasses. Repeat applications will be required for the control of perennial grasses. Add 2 pt/acre of a nonphytotoxic crop oil concentrate to the spray solution. Residual period: less than one month.


* Permit required from county agricultural commissioner for purchase or use. 1 Group numbers are assigned by the Weed Science Society of America (WSSA) according to different modes of action.

Although weeds may exhibit multiple resistance across many groups, mode of action numbers are useful in planning mixtures or rotations of herbicides with different modes of action. For more information, see http://www.hracglobal.com.

NA Not applicable.

Precautions for Using Pesticides 109 Online at http://www.ipm.ucanr.edu/GENERAL/precautions.html

This material is partially based upon work supported by the Extension Service, U.S. Department of Agriculture, under special project Section 3(d), Integrated Pest Management.

Precautions for Using Pesticides Pesticides are poisonous and must be used with caution. READ THE LABEL BEFORE OPENING A PESTICIDE CONTAINER. Follow all label precautions and directions, including requirements for protective equipment. Apply pesticides only on the crops or in the situations listed on the label. Apply pesticides at the rates specified on the label or at lower rates if suggested in this publication. In California, all agricultural uses of pesticides must be reported. Contact your county agricultural commissioner for further details. Laws, regulations, and information concerning pesticides change frequently. This publication reflects legal restrictions current on the date next to each pest's name.

Legal responsibility The user is legally responsible for any damage due to misuse of pesticides. Responsibility extends to effects caused by drift, runoff, or residues.

Transportation Do not ship or carry pesticides together with food or feed in a way that allows contamination of the edible items. Never transport pesticides in a closed passenger vehicle or in a closed cab.

Storage Keep pesticides in original containers until used. Store them in a locked cabinet, building, or fenced area where they are not accessible to children, unauthorized persons, pets, or livestock. DO NOT store pesticides with foods, feed, fertilizers, or other materials that may become contaminated by the pesticides.

Container disposal Dispose of empty containers carefully. Never reuse them. Make sure empty containers are not accessible to children or animals. Never dispose of containers where they may contaminate water supplies or natural waterways. Consult your county agricultural commissioner for correct procedures for handling and disposal of large quantities of empty containers.

Protection of nonpest animals and plants Many pesticides are toxic to useful or desirable animals, including honey bees, natural enemies, fish, domestic animals, and birds. Crops and other plants may also be damaged by misapplied pesticides. Take precautions to protect nonpest species from direct exposure to pesticides and from contamination due to drift, runoff, or residues. Certain rodenticides may pose a special hazard to animals that eat poisoned rodents.

Posting treated fields For some materials, restricted entry intervals are established to protect field workers. Keep workers out of the field for the required time after application and, when required by regulations, post the treated areas with signs indicating the safe re-entry date. Check with your county agricultural commissioner for latest restricted entry interval.

Preharvest intervals Some materials or rates cannot be used in certain crops within a specified time before harvest. Follow pesticide label instructions and allow the required time between application and harvest.

Permit requirements Many pesticides require a permit from the county agricultural commissioner before possession or use. When such materials are recommended, they are marked with an asterisk (*) in the treatment tables or chemical sections of this publication.

Maximum residue levels Before applying pesticides to crops destined for export, check maximum residue levels (MRLs) of importing country at http://www.mrldatabase.com. Processed crops Some processors will not accept a crop treated with certain chemicals. If your crop is going to a processor, be sure to check with the processor before applying a pesticide.

Crop injury Certain chemicals may cause injury to crops (phytotoxicity) under certain conditions. Always consult the label for limitations. Before applying any pesticide, take into account the stage of plant development, the soil type and condition, the temperature, moisture, and wind. Injury may also result from the use of incompatible materials.

Personal safety Follow label directions carefully. Avoid splashing, spilling, leaks, spray drift, and contamination of clothing. NEVER eat, smoke, drink, or chew while using pesticides. Provide for emergency medical care IN ADVANCE as required by regulation.

ANR NONDISCRIMINATION AND AFFIRMATIVE ACTION POLICY STATEMENT FOR UNIVERSITY OF CALIFORNIA PUBLICATIONS REGARDING PROGRAM PRACTICES

It is the policy of the University of California (UC) and the UC Division of Agriculture & Natural Resources not to engage in discrimination against or harassment of any person in any of its programs or activities on the basis of race, color, national origin, religion, sex, gender, gender expression, gender identity, pregnancy (which includes pregnancy, childbirth, and medical conditions related to pregnancy or childbirth), physical or mental disability, medical condition (cancer-related or genetic characteristics), genetic information (including family medical history), ancestry, marital status, age, sexual orientation, citizenship, or service in the uniformed services (as defined by the Uniformed Services Employment and Reemployment Rights Act of 1994 (USERRA), as well as state military and naval service. This policy is intended to be consistent with the provisions of applicable state and federal laws and University policies.

University policy also prohibits retaliation against any employee or person in any of its programs or activities for bringing a complaint of discrimination or harassment pursuant to this policy. This policy also prohibits retaliation against a person who assists someone with a complaint of discrimination or harassment, or participates in any manner in an investigation or resolution of a complaint of discrimination or harassment. Retaliation includes threats, intimidation, reprisals, and/or adverse actions related to employment or to any of its programs or activities.

In addition, it is the policy of the University and ANR to undertake affirmative action, consistent with its obligations as a Federal contractor, for minorities and women, for persons with disabilities, and for covered veterans. The University commits itself to apply every good faith effort to achieve prompt and full utilization of minorities and women in all segments of its workforce where deficiencies exist. These efforts conform to all current legal and regulatory requirements, and are consistent with University standards of quality and excellence.

In conformance with Federal regulations, written affirmative action plans shall be prepared and maintained by each campus of the University, including the Division of Agriculture and Natural Resources. Such plans shall be reviewed and approved by the Office of the President and the Office of the General Counsel before they are officially promulgated. Inquiries regarding the University's equal employment opportunity policies may be directed to Linda Marie Manton, Affirmative Action Contact, University of California, Davis, Agriculture and Natural Resources, One Shields Avenue, Davis, CA 95616, (530) 752-0495.

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