lygus management in strawberries · 2016-10-20 · • monitor strawberries in spring to determine...

Lygus Management in Strawberries

Frank ZalomFrank ZalomDepartment of EntomologyDepartment of Entomology

UC DavisUC Davis

CA Strawberry Commission MeetingOxnard, CA February 19, 2008

LygusLygusLygus hesperusLygus elisus

LygusLygusFeed on strawberry achenes, resulting in deformed fruit known as 'catfacing'.

Catfacing

Feeding on small berry

LygusLygusNot the only cause of 'catfacing.Another cause can be poor pollination'.

Catfacing

Feeding on small berry

Lygus egg

Strawberries are a reproductive host for Lygus. Eggs are inserted into plant tissues including leaves, petioles, and immature fruit.

Egg survivorship is greatest when eggs are laid in small green fruit before the achenes separate.

LygusLygus

LygusLygusIncomplete metamorphosis

Watsonville & Salinas

Santa Maria

Oxnard

Orange County

Lygus are only a significant pest north of this line, because strawberries are out of production before summer populations of Lygus build up.

San Diego

Dogma:

• Identification• Sources• Monitoring• Thresholds• Insecticides• Nonchemical controls

Bug-vacsBiological controls

Lygus managementLygus management

IdentificationIdentification

Geocoris sp.

Calocoris sp.

Can be confused with other insects such as Calocoris, Geocoris and other bugs

IdentificationIdentificationNymphs can be confused with other insects such as Calocoris and aphids Calocoris sp.

Aphids

Lygus Sources on the Central Coast Infested second year plantings Weedy hosts around fields Alternate crops and cover crops (snow peas, fava beans, etc.)

PepperweedMustards & wild radish

Blackie Rd. near CastrovilleSpence Rd. near Salinas

Lygus weed and crop hosts in central coast areasWEED HOST FEB MAR APR MAY JUN JUL AUG

Wild radish

Mustards

Chick weed

Filaree

Red maids

Shepherd's -purse

Lupines

California burclo ver

Common groundsel

Pineapple weed

Milk thistle

Spin y cocklebur

Common cockleb ur

So wthistle

Mallow (chees e weed)

California popp y

Curly dock

Smartweed

Knotweed

Lambsquarters

Pig weed

COVER CROPS

Clover

Fava beans

Vetch

Blackie Road - Prunedale(infested second year planting)

Lygus will cycle in strawberries if there is no break between crops

Monterey County

Santa Maria, Santa Barbara Co.

Pajaro River, Santa Cruz Co.

Weed Control• Flowering weeds attract Lygus, but they

can also serve as a source of adults in fields

• Control weeds in Spring while Lygus are still nymphs

Trap crop by strawberries -annual

Shasta Daisy by strawberries - perennial

Source or Sink??

Alfalfa Interplants in Cotton - Studied since the late 1960s

Grow 20' strip for every 300'Mow 1/2 every 14 daysLeave unmowed strip

Trap crops• Requires careful monitoring and

management • Control Lygus in trap crops in Spring while

Lygus are still nymphs• Once Lygus become adults, trap crops

need to be carefully managed to maintain attractiveness

• Impact of longer range Lygus migration from drying foothill weeds or other host crops is not known

• Monitor weeds in late winter to establish biofix and for control of nymphs before adults emerge

• Monitor strawberries in spring to determine when first adults appear to establish the second biofix

• Monitor strawberries during the season to establish if Lygus densities require treatment

Important to determine if and when to make a control action

Monitoring, Monitoring, Monitoring…..Monitoring, Monitoring, Monitoring…..

Monitoring guidelines

• Randomly sample a 200 foot section of bed if sampling in strawberries.

A-vac

Beating hoop or tray

Sweep net - for weeds, trap crops, and other crops Beating hoop or tray - strawberries

A-vac (or other suction devices) - strawberries

Mean number of Lygus per 10 plants Method 1988 (n=16) 1989 (n=15) Combined Whole Plant 12.6 ± 5.6 a1 14.1 ± 9.3 a 13.5 ± 7.0 a A-vac 8.5 ± 5.8 ab 15.6 ± 8.4 a 11.6 ± 6.8 ab Beating tray 6.6 ± 5.5 b 9.7 ± 4.6 a 7.9 ± 4.8 bc D-vac 6.4 ± 4.2 b 5.8 ± 5.4 b 6.1 ± 4.5 cd UC-vac ---------- 3.9 ± 2.6 b 3.9 ± 2.6 d

Comparison of Sampling Methods for Lygus in Strawberries

1 Within a column, means followed by the same letter are not significantly different (P > 0.05) by unprotected LSD

Lygus Phenology Model after Sevacherian et al.

URL - http://ipm.ucdavis.edu/WEATHER/ddretrieve.html

Degree-day Accumulations (> 54oF) Required for Each Stage of Lygus Development

Developmental stage DD (oF) DD (oC) Eggs: 252.0 140.0 Nymphs: 371.0 206.1 Egg to Adult: 623.0 346.1 Pre-Oviposition: 176.0 97.8 (Egg to Egg): 799.0 443.9

Using the Lygus DD model

Biofix 2

Biofix 1

Degree-days for LygusDegree-days for LygusAccumulate degree-days above 54° F (using local weather)Begin accumulations from the biofix: 1. First lygus nymph is found in weeds 2. First adult Lygus is found in strawberriesFirst hatch - 252° DD after the first adults found in strawberriesSecond hatch - 799° DD after the first Lygus nymphs are found in weedsThird hatch - 799° DD after the first nymphs are found in strawberries

Thresholds

Thresholds - Risk of Lygus Damage

One Lygus adult or nymph per 10 plants first One Lygus adult or nymph per 10 plants first proposed by Dr. William Allen of UC Berkeley in proposed by Dr. William Allen of UC Berkeley in the 1960s.the 1960s.

Validated by Zalom, Pickel and Welch in field Validated by Zalom, Pickel and Welch in field cage studies, 1986-87.cage studies, 1986-87.

Thresholds

Percent fruit damage (corrected for uninfested control)

Lygus/plant

Adults 1986

Adults 1987

Nymphs 1987

0.5 9.9 3.5 5.0 1.0 10.1 5.7 9.7 1.5 21.7 8.3 10.0

Monitoring guidelines

From a 200 foot section of strawberry bed.

A-vac

Beating hoop or tray

Sweep net - for weeds, trap crops, and other crops Beating hoop - treatment level is 1 Lygus nymph or adult in 20 plants A-vac - treatment level is 1 Lygus nymph or adult in 10 plants

InsecticidesInsecticides

Product Chemical Pounds Apps. Acres Agri-me k Abam e ctin 239 574 13465 Neem (variou s ) Azadirac htin (O) 56 132 2314 Bt a (various) Bt azawa i (O) 11253 667 21887 Bt k (variou s ) Bt kurs tak i (O) 14897 998 26371 Mycotrol B. bassian a (O) 11 5 41 Brigade Bifenthrin 1441 500 13685 Prev a m Borax 336 278 12630 Sevin Carbaryl 2516 70 1886 Lorsban Chlorpyrifos 3231 122 3229 Diazinon ( various) Diazinon 898 62 1089 Thiodan Endosulf a n 2330 30 1297 Danitol Fenprop a thrin 6731 1070 22035 Admire Imidaclo prid 410 44 1582 Malathio n (vario us) Malathion 76145 1674 37385 Metho myl Lanna te 16413 818 19941 Intrepid Meth oxyfenozid e (R) 757 83 3608 Dibrom Naled 19528 947 20628 Pyre thrin (variou s ) Pyre thrum (O) 40 84 1743 Este e m Pyripr oxyfe n (R) 296 167 4173 Entrus t, Suc ce ss Spinosad (R), (O) 4370 1513 45751 Oberon Spirom e sefen 768 106 3380 Acta ra Thiam e thoxa m (R) 0 0 0

Insecticides registered for use on strawberries, and use in 2005

Insecticides with Lygus on label - do they work? Are they cost-effective?

Fruit evaluated at 20 d post treatment were damaged following treatment

Lygus/plant % damage Insecticide

1 d before application

1 d after application

20 d after application

@ 20 d after application

malathion 0.10±0.04 0.03±0.02 0.70±0.33 19.30±3.90 methomyl 0.07±0.02 0.03±0.02 0.53±0.28 14.10±1.99 fenpropathrin 0.15±0.07 0 0.06±0.06 8.40±2.20 untreated 0.08±0.03 0.09±0.07 1.09±0.48 29.40±6.67

Effect of insecticide application on total Lygus per plant and % fruit damage (mean±SE of 5 fields), 1996

Study was conducted when Brigade and Danitol were first registered for use on strawberries in 1996.

1 Average calculated from gross returns 1994 through 1996 2 Application costs = $23.50/acre

Treatment and rate

Unit price

Cost of product1

Re ven ue increa s e 2

Net $ increa s e

Malathion 3 pt $27.25/ga l $10.22 $1204 $1170.28 Lannate 1 lb $21.60/l b $21.60 $1823 $1777.90 Brigade 1pt $204. 50/gal $25.56 $2501 $2452.39

Net revenue increase per acre resulting from the reduction of Lygus damage due to insecticide treatment, 1994-96

Limited strawberry acreage in U.S. Short harvest intervals Worker exposure Risk cup High potential consumption Consumed by children High residues because of short PHI Liability High value crop Low damage tolerance Susceptible to phytotoxicity Expense of research Frequent sampling of insects and damage Generally low densities in strawberry fields Crop destruct costs (unregistered products) Large plots for mobile pests like Lygus

What are challenges to insecticide registration on strawberries?

Pesticide Chemical S ubgro up Target Site of Ac tivity IRAC # Lann ate met homyl carbamate acet ylcholine esterase inh ibitor 1A Malathion ma lathion orga nop hosp hate acet ylcholine esterase inh ibitor 1B Dibrom na led prga nop hosp hate acet ylcholine esterase inh ibitor 1B Brigade bifenthrin pyrethroid sodi um chann e l mod ulator 3 Da nitol fempropat hrin pyrethroid sodi um chann e l mod ulator 3 Actara thiamet hoxam neo nicotinoid nicotinic Ach receptor ago nists/

antago nist 4A

Prevam borax borax nonspecific inhibitor uncl Warrior cyhalothrin pyrethroid sodium channel modulator 3 Assail acetamiprid neonicotinoid nicotinic Ach receptor agonists/

antagonist 4A

-- clothianidin neonicotinoid nicotinic Ach receptor agonists/ antagonist

4A

Venom dinotefuran neonicotinoid nicotinic Ach receptor agonists/ antagonist

4A

Beleaf flonicamid flonicamid nonspecific feeding blocker 9C Rimon novaluron benzoylureas inhibitor of chitin biosynthesis,

type 0 15

-- metaflumizone semicarbazone blocks sodium channel 22

Registered and Candidate Insecticides

Being withdrawnRegisteredNot registered for use on strawberries, but under study

Lygus Bug Control, Watsonville, 2007

1 Not registered for use on strawberries Application date - August 10, 2007 n=3 replicates 10 flowers/plot; washed through filter paper in ETOH, counted under dissecting microscope

Product Chemical name Rate per ac. (form) Label Untreated -- -- -- Danitol Fenpropathrin 10.67 oz Yes Assail-L + Dyneamic Acetamiprid + Surfactant 5.0 oz + 0.25% v/v No Assail-H + Dyneamic Acetamiprid + Surfactant 7.0 oz + 0.25% v/v No Assail-L + Danitol + Dyneamic

Acetamiprid + Fenpropathrin + Surfactant

5.0 oz + 10.67 oz + 0.25% v/v No

Rimon Novaluron 12.0 oz No Rimon (2 applications) Novaluron 12.0 oz No Actara 25 WG Thiamethoxam 4.0 oz Yes Actara 25 WG + Danitol Thiamethoxam + Fenpropathrin 4.0 oz + 10.67 oz Yes Actara 25 WG + Dibrom Thiamethoxam + Naled 4.0 oz + 1 Yes Clothioanidan Clothioanidan 2.0 oz No Beleaf 50% SG Flonicamid 2.8 oz No Dibrom Naled 1 pt Yes

• Fall planted var. PS1269• Plot size - 3 beds x 30 feet• Buffer between plots - 8 feet (planted)• Treatments applied on August 10 Second application of Rimon on August 17• Three row tractor mounted sprayer 100 gal/acre; 60 psi • Completely randomized design, 3 replicates• Sampling - hand-beating 40 plants from the middle

row of each plot

Lygus Bug Control, Watsonville, 2007

Lygus Present in Untreated Plots, 2007

Action threshold

Lygus Bug Control, Watsonville - adults

1 Means followed by * are significantly different from untreated at p=0.05 when compared by Students t-test following Log(mean+0.1)*10 transformation.ANOV statistics for each date: 8/16/07, df=12, 38, F=1.1109, P=0.3926

8/23/07, df=12, 38, F=1.2267, P=0.31778/30/07, df=12, 38, F=2.9658, P=0.00989/6/07, df=12, 38, F=1.591, P=0.1558

Mean ± SE adults per plant1 Treatment Pre 8-2-07 8/16/07 8/23/07 8/30/07 9/6/07 Untreated 0.06 ± 0.02 0.04 ± 0.01 0.04 ± 0.01 0.07 ± 0.01 0.06 ± 0.02 Danitol 0.05 ± 0.03 0.02 ± 0.01 0.03 ± 0.01 0.03 ± 0.01* 0.05 ± 0.03 Assail-L 0.06 ± 0.02 0.02 ± 0.02 0.00 ± 0.00 0.05 ± 0.02 0.06 ± 0.02 Assail-H 0.06 ± 0.01 0.01 ± 0.01 0.01 ± 0.01 0.01 ± 0.01* 0.06 ± 0.01 Assail-L + Danitol 0.03 ± 0.02 0.01 ± 0.01 0.00 ± 0.00 0.00 ± 0.00* 0.03 ± 0.02 Rimon 0.03 ± 0.02 0.01 ± 0.01 0.03 ± 0.01 0.01 ± 0.01* 0.03 ± 0.02 Rimon (2 apps) 0.02 ± 0.01 0.03 ± 0.02 0.04 ± 0.01 0.00 ± 0.00* 0.02 ± 0.01 Actara 0.02 ± 0.01 0.04 ± 0.02 0.01 ± 0.01 0.04 ± 0.02 0.02 ± 0.01 Actara + Danitol 0.00 ± 0.00 0.00 ± 0.00 0.01 ± 0.01 0.01 ± 0.01* 0.00 ± 0.00 Actara + Dibrom 0.03 ± 0.01 0.02 ± 0.02 0.02 ± 0.02 0.03 ± 0.01* 0.03 ± 0.01 Clothioanidan 0.04 ± 0.01 0.01 ± 0.01 0.03 ± 0.03 0.04 ± 0.01 0.04 ± 0.01 Beleaf 0.01 ± 0.01 0.00 ± 0.00 0.04 ± 0.02 0.00 ± 0.00* 0.01 ± 0.01 Dibrom 0.04 ± 0.03 0.03 ± 0.01 0.04 ± 0.02 0.03 ± 0.01* 0.04 ± 0.03

Not registeredRegistered

Lygus Bug Control, Watsonville - nymphs Mean ± SE nymphs per plant1 Treatment Pre 8-2-07 8/16/07 8/23/07 8/30/07 9/6/07 Untreated 0.35 ± 0.04 0.43 ± 0.20 0.43 ± 0.06 0.38 ± 0.05 0.33 ± 0.02 Danitol 0.18 ± 0.06 0.07 ± 0.02 0.13 ± 0.04* 0.13 ± 0.03* 0.22 ± 0.03 Assail-L 0.26 ± 0.04 0.17 ± 0.04 0.23 ± 0.05 0.15 ± 0.04* 0.35 ± 0.23 Assail-H 0.21 ± 0.02 0.16 ± 0.11 0.21 ± 0.02* 0.27 ± 0.03 0.34 ± 0.09 Assail-L + Danitol 0.13 ± 0.03 0.18 ± 0.05 0.13 ± 0.03* 0.17 ± 0.02* 0.34 ± 0.13 Rimon 0.23 ± 0.04 0.10 ± 0.07 0.07 ± 0.03* 0.22 ± 0.05 0.27 ± 0.06 Rimon (2 apps) 0.24 ± 0.05 0.08 ± 0.00 0.18 ± 0.07* 0.21 ± 0.05* 0.41 ± 0.10 Actara 0.32 ± 0.09 0.13 ± 0.05 0.15 ± 0.01* 0.23 ± 0.03 0.23 ± 0.07 Actara + Danitol 0.17 ± 0.03 0.08 ± 0.01 0.08 ± 0.05* 0.07 ± 0.03* 0.13 ± 0.03 Actara + Dibrom 0.21 ± 0.02 0.17 ± 0.03 0.08 ± 0.03* 0.15 ± 0.03* 0.23 ± 0.02 Clothioanidan 0.21 ± 0.02 0.08 ± 0.02 0.11 ± 0.02* 0.14 ± 0.04* 0.20 ± 0.10 Beleaf 0.26 ± 0.03 0.09 ± 0.01 0.14 ± 0.03* 0.17 ± 0.07* 0.21 ± 0.07 Dibrom 0.29 ± 0.06 0.08 ± 0.02 0.18 ± 0.06* 0.17 ± 0.02* 0.23 ± 0.09 1 Means followed by * are significantly different from untreated at p=0.05 when compared by Students t-

test following Log(mean+0.1)*10 transformation. ANOV statistics for each date:

8/16/07, df=12, 38, F=1.7839, P=0.1053 8/23/07, df=12, 38, F=3.4892, P=0.0037 8/30/07, df=12, 38, F=3.1341, P=0.0071 9/6/07, df=12, 38, F=0.7466, P=0.6956

Not registeredRegistered

Lygus Bug Control, Watsonville - Mixtures Mean ± SE adults per plant1 Treatment Pre 8-2-07 8/16/07 8/23/07 8/30/07 9/6/07 Untreated 0.39 ± 0.05 0.47 ± 0.21 0.46 ± 0.06 0.45 ± 0.04 0.39 ± 0.03 Danitol 0.21 ± 0.07 0.09 ± 0.02* 0.16 ± 0.03* 0.15 ± 0.04* 0.27 ± 0.04 Actara 0.33 ± 0.09 0.18 ± 0.04 0.16 ± 0.01* 0.26 ± 0.02 0.24 ± 0.06 Actara + Danitol 0.23 ± 0.05 0.09 ± 0.01* 0.09 ± 0.06* 0.08 ± 0.04* 0.13 ± 0.03*

1 Means followed by * are significantly different from UTC at p=0.05 when compared by Students t-test following Log(mean+0.1)*10 transformation.ANOV statistics for each date:

8/16/07, df=3, 11, F=5.1412, P=0.23458/23/07, df=3, 11, F=7.1814, P=0.01178/30/07, df=3, 11, F=13.5077, P=0.00179/6/07, df=3, 11, F=6.006, P=0.0191

Caution - using mixtures may increase chance of resistance!

Lygus Bug Control, Watsonville - Bioassays

Treatments Concentration

ppm Rate/ac (product)

Mean ± SE percent alive1

(48 hrs)

Mean ± SE adults/plant1

(1 week) Water -- -- 86.67 ± 6.67 0.47 ± 0.21 Danitol 257.58 10.67 oz 13.33 ± 13.33* 0.09 ± 0.02 Actara 74.94 4.0 oz 33.33 ± 17.64* 0.18 ± 0.04 Actara + Danitol

74.94 (Ac) + 257.58 (Da)

4.0 oz (Ac) + 10.67 oz (Da) 6.67 ± 6.67* 0.09 ± 0.01

Rimon 87.19 12.0 oz 93.33 ± 6.67 0.11 ± 0.07 1 Means followed by * are significantly different from UTC at p=0.05 when compared by Students t-test following Log(mean+0.1)*10 transformation.

Centrifuge tube bioassay of the same Lygus population present in the strawberry field

Results similar for insecticides with contact activity, but not for insect growth regulator (Rimon)

Nymphs treated were 1st or 2nd instar; 5 lygus nymphs/petri dish; Treated August 9, 2005 1 ANOVA statistics: F= 108.78, df=2,10, P<0001 @ 24 hrs; F= 11.03, df=2,10, P= 0.0050 @ 48 hrs 2 ANOVA statistics: F= 1.52, df=2,10, P=0.2753 @ 24 hrs; F= 8.48, df=2,10, P= 0.0106 @ 48 hrs * Means significantly different from untreated by StudentÕs t-test at p<0.05 following arcsine transformation. ** Means significantly different from untreated by LSD at p<0.05.

Mean ± SD percent survival 1

Treatment Rate

(form/ac) 24 hr 48 hr Untreated water 100.0 ± 0.0 85.0 ± 14.0 Nova luron 12.0 oz 73.0 ± 11.6 * 33.0 ± 23.0 * Nova luron 9.0 oz 47.0 ± 11.6 * 20.0 ± 0.0 *

Lygus Nymph Bioassay, Rimon (Novaluron)

Mean ± SD caste skins 2

Treatment Rate

(form/ac) 24 hr 48 hr Untreated water 0.80 ± 0.84 A 2.80 ± 1.64 A Nova luron 12.0 oz 0.00 ± 0.00 A 0.67 ± 1.15 B Nova luron 9.0 oz 0.33 ± 0.58 A 0.00 ± 0.00 B

1 Treatment dates, May 13, May 20

Lygus Field Evaluation, Watsonville, 2005 Lygus per 10 beat sheet samples (n=4) Treatment Rate May 20 May 27 June 3 June 10 Untreated -- 1.00 ± 1.15 1.25 ± 1.50 2.25 ± 1.50 1.00 ± 1.15 Danitol 10 2/ 3 oz 0.50 ± 1.00 2.00 ± 3.37 2.25 ± 2.63 1.00 ± 0.82 Malathion 2.0 pts 0.75 ± 0.96 3.25 ± 1.26 2.25 ± 2.63 2.50 ± 3.79 Acta ra 4.0 oz 0.25 ± 0.50 2.00 ± 0.82 3.00 ± 1.83 0.75 ± 0.96 flonicamid 0.34 lb 0.25 ± 0.50 0.25 ± 0.50 1.25 ± 0.96 1.00 ± 0.82 novaluron (2X) 12.0 oz 0.00 ± 0.00 0.00 ± 0.00 1.00 ± 1.15 2.25 ± 3.86 Assail 1.7 oz 0.50 ± 0.58 1.75 ± 0.96 1.00 ± 1.41 2.00 ± 1.41

RegisteredNot registered for use on strawberries

Lygus Resistance

Santa Maria - 2 sites

Lygus Resistance Monitoring

Watsonville - 2 sites

Blackie Rd.

Salinas

UC Davis - alfalfa

0102030405060708090

100

GareySanta MariaSalinasPrunedaleRiverside RdSan AndreasUC Davis

0102030405060708090

100


Malathion Malathion 200 200 ugug in Bioassay Bag in Bioassay Bag

Methomyl (Lannate) Methomyl (Lannate) 1.5 1.5 ugug in Bioassay Bag in Bioassay Bag

0102030405060708090

100


Bifenthrin (Brigade) Bifenthrin (Brigade) 100 100 ugug in Bioassay Bag in Bioassay Bag

0102030405060708090

100


Fenpropathrin (Danitol) Fenpropathrin (Danitol) 100 100 ugug in Bioassay Bag in Bioassay Bag

Proportion of Lygus Bugs Killed

Resistance Management for Pyrethroids

Brigade bifenthrinDanitol fenpropathrinWarrior lambda-cyhalothrin

IRAC (Insecticide Resistance Action Committee) Class 3

Primary site of actionSodium channel modulators

Resistance Management for NeonicotinoidsIRAC Class 4a

Primary site of actionNicotinic acetylcholine receptor agonists/antagonists

Actara thiamethoxamAdmire imidaclopridAssail acetamiprid

clothianidin

Bug Vacs

Three row bug vac

Two row bug vac

One row bug vac

Three row bug vac evaluation, 1989

Location - Watsonville, CAVariety - Winter planted 'Selva'Treatments:

• Vacuum weekly• Vacuum twice weekly after reaching

threshold• Bifenthrin applied twice (timed to nymphal

hatch)• Untreated

Three row bug vac evaluation, 1990

Location - Watsonville, CAVariety - Winter planted 'Selva'Treatments:

• Vacuum weekly• Vacuum twice weekly• Vacuum weekly with malathion applied twice

(timed to nymphal hatch)• Malathion applied twice (at nymphal hatch)• Bifenthrin applied twice (at nymphal hatch)• Untreated

• Plot size - 150 ft x 3 beds• 4 replicates• All samples taken from middle bed• Lygus sampled by beating hoop• Fruit sampled - large green fruit, 50 at random

per plot• Data summed across weeks and divided by

the total number of samples to obtain the average per replicate per year.

Three row bug vac evaluation, 1989 and 1990Design

Mean (+SD) Lygus per 10 beat sample

Treatment Nymphs Adults Damaged fruit Vacuum weekly 3.9+1.7b 0.5+0.2b 14.7+2.0b Vacuum at threshold

4.9+0.9ab 0.7+0.3ab 18.1+3.5ab

Bifenthrin1 0.4+0.3c 0.1+0.1b 5.8+0.9c Untreated 6.8+1.9a 1.9+0.6a 23.3+0.3a

Mean (+SD) number of Lygus and number of cat-faced fruit per 50 large green fruit in a field using a three row bug vac, 1989.

Means followed by the same letter do not differ significantly at P<0.05 by Fisher’s Protected LSD following Log (x+1) transformation.1 Brigade applied at 0.1 lb. a.i./acre on May 19, 1989 and July 10, 1989

Mean (+SD) number of Lygus and number of cat-faced fruit per 50 large green fruit in a field using a three row bug vac, 1990.

Means followed by the same letter do not differ significantly at P<0.05 by Fisher’s Protected LSD following Log (x+1) transformation.1 Malathion applied at 1.25 lb. a.i./acre on May 6, 1990 and July 10, 19902 Brigade applied at 0.1 lb. a.i./acre on May 6, 1990 and July 10, 1990

Mean (+SD) Lygus per 10 beat sample

Treatment Nymphs Adults Damaged fruit Vacuum weekly 24.2+5.9b 6.0+1.6ab 17.2+3.3b Vacuum 2X weekly

26.0+3.7b 7.5+1.3a 18.1+3.7b

Vacuum + malathion

20.7+7.6b 3.7+0.9ab 17.5+4.0b

Malathion1 24.7+3.3b 4.3+0.9ab 16.0+2.0b Bifenthrin2 0.8+0.5c 2.0+0.8b 5.3+2.1c Untreated 52.5+18.4a 9.5+2.1a 27.3+3.0a

Fruit damage reduction

0

10

20

30

40

50

60

0 5 10 15 20 25Air flow (km/h)

Damage reduction

Percent reduction of cat-faced fruit in plots vacuumed weekly in relation to vacuum machine air flow.

Generalist predators

big eyed bugbig eyed bugGeocoris Geocoris sp.sp.

minute pirate bugminute pirate bugOrius Orius sp.sp.

spidersspiders

Parasitoids Anaphes iole

Lygus parasitism by naturally-occurring Anaphes is low in strawberry fields, and does not afford economic control.

Inoculative releases of Anaphes iole have been studied. Parasitism of eggs was around 43% at a release rate of about 37,500 per acre.Greatest promise is increased parasitism in natural areas to reduce overall abundance.

Peristenus releasesParasitoidsParasitoids

Watsonville & Salinas

Santa Maria

Oxnard

Orange County

Lygus are only a significant pest north of this line, because strawberries are out of production before summer populations of Lygus build up.

San Diego

Lygus in Oxnard?Lygus in Oxnard?

Lygus in Oxnard?Temperatures/rainfall? Spring rains - more hosts in foothillsAlternate hosts? Foothills? Weeds? Crops?Summer plantings?

Oxnard Precipitation

0

0.5

1

1.5

2

2.5

1/1 1/8 1/151/221/29 2/5 2/122/192/26 3/5 3/123/193/26 4/2 4/9 4/164/234/30 5/7 5/145/215/28Date

Precipitation (inches)

Precipitation 2006(inches)Avg. precipitation(inches)

More rainfall - more spring hosts?

4-Apr 12-A pr 20-A pr 27- Apr 4 -May 11-Ma y 18-May 25-M ay 1-J un 8-Ju n 15 -Jun 22-Jun 2 9-Jun 6-Jul 13-J ul 20 -Jul 27 -Jul 1 -Aug 10-Au g 17-Aug 24-A ug 31 -Aug 7-S ep 1 4-Sep 21-Sep 27-S ep 5-Oct 12- Oct 1 9-Oct 2- Nov 9-Nov 16-N ov 22-No v 30-N ov 7- Dec 4-Jan 10-Jan 18-Ja n 25- Jan 1-Feb 8- Feb

Winter BerriesLima BeanTomatoSummer Berries

Num

bers

Apr May Jun Jul Aug Sept Oct Nov Dec Jan Feb Mar

Strawberries and alternate hostsGreenhouse whiteflies

4-Apr 12-A pr 20-A pr 27- Apr 4 -May 11-Ma y 18-Ma y 25-M ay 1-J un 8-Ju n 1 5-Jun 22-Jun 2 9-Jun 6-Jul 13- Jul 2 0-Jul 27 -Jul 1-Aug 10-Au g 17-Au g 24-A ug 31 -Aug 7-S ep 1 4-Sep 21-Sep 27-S ep 5-Oc t 12- Oct 1 9-Oct 2 -Nov 9-Nov 16-N ov 22-No v 30- Nov 7 -Dec 4-Jan 10-Jan 18-Ja n 25- Jan 1-Fe b 8- Feb

Winter Berries??Summer Berries

Num

bers

Apr May Jun Jul Aug Sept Oct Nov Dec Jan Feb Mar

Strawberries and alternate hosts

Lygus

Areawide ManagementFor optimum management, the continuous development of Lygus must be broken:• Identify Lygus sources• Alternate host abatement• Minimize overlap of strawberry plantings

- second year and summer plantings• Control infestations on all hosts

Resources

Lygus Management in Strawberries

Frank ZalomFrank ZalomDepartment of EntomologyDepartment of Entomology

UC DavisUC Davis

CA Strawberry Commission MeetingOxnard, CA February 19, 2008

lygus management in strawberries · 2016-10-20 · • monitor strawberries in spring to determine...

Documents