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IPM-9 Kentucky Backyard Apple Integrated Pest Management Manual MANUAL PREPARED BY ENTOMOLOGY Ric Bessin PLANT PATHOLOGY John Hartman HORTICULTURE Jerry Brown John Strang Terry Jones IPM COORDINATOR Doug Johnson January 1994 This manual is provided by the Kentucky Integrated Pest Management Program.

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Page 1: Kentucky Backyard Apple Integrated Pest Management Manualipm.ca.uky.edu/files/ipm9hmap.pdf · 2017-03-06 · IPM-9 Kentucky Backyard Apple Integrated Pest Management Manual MANUAL

IPM-9

Kentucky Backyard Apple

Integrated Pest Management

Manual

MANUAL PREPARED BY

ENTOMOLOGYRic Bessin

PLANT PATHOLOGYJohn Hartman

HORTICULTURE

Jerry BrownJohn StrangTerry Jones

IPM COORDINATOR

Doug Johnson

January 1994

This manual is provided by the Kentucky Integrated Pest Management Program.

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I. INTRODUCTIONHomeowners plant apple trees for a

variety of reasons: for the benefit of fresh fruit,for control over what types of pesticides andfertilizers are applied, to save money, as alearning experience for their children, to growdifferent or exotic varieties, or simply for theenjoyment of raising their own produce. Despitethe diversity of reasons for raising apples, homegardeners want to produce quality fruit.

Home gardeners are troubled by anumber of pests attacking apples. Many do notunderstand the biology of the pests and theimportance of good cultural practices andappropriate timing of pesticide applications.Often pesticides are applied when they will dolittle good, leading the gardener to use themmore often or at higher concentrations.Frequently the wrong pesticide is used tocontrol a particular pest. Some are leftwondering whether the fruit is safe to eat.Gardeners, especially those trying to raise fruitwith little or no pesticides often end up withunacceptable fruit due to disease and insectdamage. Many give up trying to grow appleswhen their expectations are not met.

In general, the public is becoming moreconcerned about the environment, pesticides,and the food we eat. Recent surveys indicatethat over 80% of consumers are concernedabout pesticide residues in food. Additoinally,the use of pesticides in the urban environment isa major concern among many homeowners.While home fruit growers have fewer chemicalalternatives available than do commercialgrowers, the greatest pesticide use occurs in theurban setting. Home fruit growers able toproduce quality fruit with reduced pesticideusage are pleased that they are consuming ahealthy food and contributing to a saferenvironment.

Participants in this program shouldexpect to alter pesticide use patterns andapplication timing while maintaining anacceptable level of quality. There is a greaterreliance on a number of other strategies rather

than sole reliance on chemical control.However, while there is less chemical input,there is probably as much or more timeinvolved. Those growing fruit will have theopportunity to develop a better understanding oftrees and pest biology. This is a valuablelearning experience.

A. INTEGRATED PEST MANAGEMENTHome fruit spray guides are often

developed around a calendar schedule that willprevent losses from all pests known to occur ina region throughout the growing season. Theseguidelines, when followed properly, will providethe gardeners with a maximum amount of highquality fruit at the end of the season. However,most home plantings do not need to beprotected against all pests throughout the wholegrowing season. Experience in Kentucky hasshown us that pest problems are usuallysporadic and site specific. For any particularsituation, some pesticide applications are notnecessary.

An integrated pest management (IPM)program for apples has been developed toprovide home gardeners with guidelines to raisequality fruit with a minimum level of pesticideuse. Integrated pest management is a productionsystem which uses information about hosts,pests, and the environment to determine thepotential for pest injury and select appropriatecultural, biological, or chemical tools in light ofeconomic, social and environmental concerns.Pesticides are used only as a last resort, after theappropriate preventative cultural and biologicalpractices have been used. This system results inless pesticide usage than conventionalproduction systems. However, urban apple IPMis not simply a "recipe" to follow. There arevarious types of management options available.Selecting the type of IPM program to be

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Table 1. Sequence of steps involved in making pest management decisions

Step Description

Prevention Orchard pest management begins with using appropriate culturalpractices that will prevent, reduce, or delay pests from reachingdamaging levels.

Detection Pest need to be detected and monitored early, before serious lossesoccur. This is best accomplished through regular and frequentexaminations of the trees and fruit.

Identification Pests and/or the damage they cause must be properly identified. Thedifferent stages of the pest should be recognized. Without properidentification, pests cannot be managed properly.

Evaluation of PestSignificance

Once the pest is identified, its potential impact (significance) needs to bedetermined. This involves recognizing the type of damage it will cause(foliar, fruit, or to the tree itself), and evaluating the pest level. Often aserious pest at low numbers is unimportant, while a minor pest at highnumbers can cause serious damage.

Selection ofManagementOptions

If a pest is at levels which require management, the most appropriatemanagement option needs to be selected from the available alternatives.Stage of the pest and crop, other pests present, effect on beneficialorganisms (pollinators and natural enemies of pests), cost of control,level of control expected, as well as potential social and environmentalimpacts need to be evaluated when making this selection.

Evaluation ofControl

After a control action has been made, the level of control needs to beevaluated. Has the pest level returned to acceptable levels? Was theexpected level of control obtained? Use this information in the futurewhen selecting management options.

implemented will depend on the expectations ofthe gardener, the site-specific pest problems,and the amount of time and resources he/she iswilling to commit. The home gardener is not bound bymarket quality standards or economicjustification of certain cultural practices. Thus,there is greater flexibility in the use of appleIPM. IPM in the urban setting relies much moreheavily on cultural control of pests. These arepreventive in nature and are often referred to as"good farming practices" in commercialagriculture. Good cultural practices include theuse of disease resistant cultivars and proper siteselection when establishing new plantings, handthinning of fruit, timely sanitation of prunings

and fruit drops, fertility management, pestmating disruption through mass trapping,adequate tree pruning, and use of physicalbarriers around the trees and fruit.

Pest predictors are available for applescab, fire blight, codling moth, and San Josescale. These allow you to monitor these pestsaccurately and treat only when they are at levelswhich may cause significant damage, and whenthey are most vulnerable. These predictors willallow you to eliminate, reduce or improvetiming of pesticide use for some of the mostdamaging apple pests. These predictive systemsdo require that the gardener maintain weatherrecords including minimum and maximumtemperature and rainfall. Insect traps are

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available to monitor for the presence of some ofthe damaging insect pests.

B. DETERMINING WHAT AREACCEPTABLE LOSSES AND THE NEEDFOR ACTION

With IPM, the objective is not tocompletely eliminate the pests. Elimination of apest is an unrealistic objective that commonlyleads to additional problems including excessivepesticide use, pest resistance, and outbreaks ofsecondary pests. Rather the idea is to keep thembelow a level at which they will not causesufficient damage to require control. In fact, afew individuals of a particular pest are oftendesirable. These help to maintain beneficialorganisms that serve to regulate pests. Withhome apple production, as long as the gardeneris a able to harvest enough apples at the qualitydesired it shouldn't matter if a few are lost topest damage. Several apple pests cause onlysurface blemishes on the fruit which do notaffect the flavor or nutritional quality of thefruit. For some gardeners, 50% of a crop isenough, others may want 90% or moreacceptable fruit. It is important to decide whatlevel of damage you are willing to accept beforedeveloping an IPM program. Those willing toaccept slightly higher levels of fruit damage willbe able to reduce pesticide usage considerably.Before beginning this program you will need todecide what types and levels of pest damage youare willing to accept; we ask you to share yourobjectives with us in the participant'squestionnaire.

The level at which we try to keep pestsbelow is often referred to as the EconomicThreshold. When a pest exceeds the economicthreshold and is left uncontrolled, it will causeunacceptable levels of damage. Below theeconomic threshold, pests may cause minor buttolerable levels of damage. Economic thresholdspresented in this manual are conservative,designed to provide 90 to 95% acceptable fruit.Growers are encouraged to modify these valuesto meet their specific expectations.

C. WHAT TO EXPECT FROM THE UKAPPLE IPM PROGRAM

You, the grower, are in charge. Thisprogram will provide information and guidelinesfor your use. But the decisions will be yours.There will be an IPM expert at the countyextension office or a volunteer in yourcommunity to distribute IPM information andanswer questions. The University of KentuckyCooperative Extension Service will provide thetechnical support, training (field days anddemonstrations), and training materials (thismanual) for this program.

This program is new. We encourageyour comments and suggestions that willimprove this program to better serve your needsand expectations.

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II. HORTICULTURAL MANAGEMENT Management of many of the key pests

that attack apples begins long before the pestsreach damaging levels. In fact, some factors thatmay predispose apples to pest losses need to beconsidered before the young trees are purchasedand planted. Cultural practices listed below havethe potential to greatly delay, reduce or avoiddamage from some pests. It is important tomaintain an environment which is unfavorable tothese pests. These non-chemical practices arethe foundation of an integrated pestmanagement program and are criticallyimportant in managing home apple plantings.

A. BEFORE PLANTING

Site Selection Many pests and diseases are more

serious in moist, shady locations. Plant newtrees in a sunny well, drained locations. North oreast facing slopes make good sites because theyhave good air drainage and they are cooler inthe spring, thus are less apt to have frost orfreeze injury during bloom. If soil is constantlywet, improve soil drainage by ditching or tiling.Apple scab, powdery mildew and fruit rotdiseases are more serious in moist, shadedlocations. Many pests that attack apple havewild and cultivated hosts on which they develop.Avoid planting apples near a forest, near wildbrambles, or cedar trees. These plants harbordisease organisms and insects that attack apples.

Landscaping With FruitIn choosing fruit to plant at home, you

want to consider not only how it tastes but whatit will look like. While commercial fruit growerstry to attain maximum yields, the homeownerhas multiple goals and should be willing tosacrifice a percentage of the harvest for someaesthetic effect. In this situation, increasedcompetition among plants will cause somedecrease in production, but you can still have

plenty of fruit.

Planning Varieties for the LandscapeYou need a comprehensive plan for your

landscape. Explore the UK CooperativeExtension Service recommendations to decidewhat varieties of ornamental and edible plants togrow. As you plan your landscape, feel free tomix edible and ornamental plants for a pleasingeffect but be sure to consider maintenancerequirements of each plant. You may wish tokeep edible plants in groups or to mix them withornamentals not requiring special pestmanagement.

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ADVANTAGES OF DWARF TREES:

T They fruit much sooner.

T They bear less fruit per tree. With severaltrees and varieties you will have enough fruitof each, but not so much that it becomes aproblem, as often happens with standardtrees.

T Fruit is usually larger and morehighly-colored than in the same variety onstandard rootstocks.

T You can reach all parts of the tree easily.Therefore, all operations may be performedfrom the ground or from a small stepladder.

T Smaller, less expensive spray equipment isneeded.

T Dwarf fruit trees are easier to prune, trainor espalier than standard trees because theyare slower growing.

Cultivar SelectionApple cultivars differ in their

susceptibility to some pests. A number ofcultivars are available which are resistant toapple scab, cedar apple rust, fire blight, andpowdery mildew. Certain cultivars are moresusceptible to rosy apple aphid and Europeanred mites. Resistant and susceptible cultivars arelisted under the respective pests. Generally,cultivars that mature early in the season escapemuch of the pest damage and are recommendedfor the urban growers. Early maturing cultivarsare generally sprayed less and harvested beforeserious pest problems develop. Only applecultivars that are suited to a particular areashould be chosen. Dwarf or semi-dwarf trees areattractive to home fruit growers because theyare easier to spray, prune and harvest. Thesmaller trees allow more cultivars in the samespace. Cultivar selection is based on thefollowing:

QualitySelect only high quality varieties that

have proven their merit through the test of time.Remember that many varieties not suited forcommercial production may be very good in thehome garden. See Table 1 of ID-21. To prolongyour harvest, you may want to plant severalvarieties that mature at different times. Freshtasting apples may be had almost all year if youplant the right varieties and store them properly.

Disease ResistanceSelect apples resistant to diseases so that

fewer losses occur and so that fewer sprays areneeded. See ID-21, included in the appendix, fora list of the recommended varieties and theirresistance to the common diseases. In additionto the disease resistant varieties listed in ID-21,'Gold Rush' and 'Enterprise' have exceptionalfruit quality and disease resistance.

Dwarf FruitThe advent of dwarfed fruit trees has

opened the way for successful tree fruit growing

by the urban homeowner. Dwarfed treesproduce the same quality fruit as larger standardtrees.

Apples are dwarfed principally bygrafting the desired variety onto special clonalrootstocks. However, apples may also bedwarfed by grafting dwarfing interstems into thetrunk above ground. The most importantdwarfing clonal rootstocks in use today weredeveloped in England and are designated aseither M. (for “East Malling” or MM. (for“Malling Merton”). While many exist, only 5having value forthe home landscape will bementioned here. Figure 3 illustrates sizereduction of apple trees using dwarfingrootstocks. Table 2 lists important factors toconsider prior to choosing a dwarfing rootsotck.

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In many cases you will only be able topurchase a tree on a dwarf, semidwarf orseedling rootstock and will not be told thespecific rootstock used by the nursery.However, with some nurseries a choice ofspecific rootstocks is possible.

Dwarfing characteristics of rootstocksare shown in line 1 of Table 2. These indicatethat a Redfree variety on a M.7 rootstock willbe 55% the size of a Redfree tree on a seedlingrootstock at any time during its life. Rememberthat trees are not like people-they don't stopgrowing when they reach a particular height.Rather, they will continue to grow in sizethroughout their life and a dwarf tree canbecome quite tall. Size of a tree is regulated bythe rootstock, amount of annual pruning, varietyof apple selected and how well the tree crops.

Dwarfing characteristics are not the onlyaspect that should be considered in selecting arootstock. If you have selected a variety that issusceptible to fireblight disease, Table 2indicates that you would not want to put it onrootstock that is susceptible to fireblight such asM.9 or M.26. If you have very heavy clay soilthat tends to be slightly wet, semidwarfMM.111 rootstock would be your best choice,but does not produce fruit as early as on asmaller semidwarf or dwarf rootstock.

In Kentucky, the M.7 and MM.111

rootstocks have performed well. The expectedfruit yield for dwarf apple trees, is 1 bushel pertree in the fifth year and 4 bushels per tree in the9th year.

Choosing Nursery StockOrder plants only from reputable

nurseries to insurance that they will be true toname, well-grown, free from insects and disease,and packed and shipped correctly.

Size and AgeBuy only vigorous trees. One-year old

stock, if well grown, is usually the best- notbecause it costs less, but because trees establishthemselves sooner, survive better, and can beshaped by the grower with a minimum ofcutting.

When to OrderGet plant orders in early so they will be

filled as specified. If ordering is delayed, supplyof some cultivars may be exhausted, only secondgrade material may be left, or the order mayarrive too late for the best planting time. Specifyon the order blank the time of shipmentpreferred. Apples may be planted in spring orfall. For fall planting, order plants from anorthern nursery.

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Heeling In

T Select a well-drained place and dig atrench of sufficient size to contain roots of theplants.

T If plants are tied in bundles, separate themto fan out roots so that soil can be packedaround them. This method eliminates airpockets.

T Slant trees to the southwest so the sun willnot shine directly on exposed trunks andcause sunburn.

T Firm soil well and mound it around theplants to furnish good drainage.

T If the soil is dry at heeling-in time,water plants before mounding. Stock willkeep in good condition for an indefiniteperiod of time when properly heeled in.

TABLE 2. IMPORTANT CONSIDERATIONS IN SELECTION OF ROOTSTOCKS

Factor to Consider

Clonal Stocks

SeedlingM.9 M.26 M.7 MM.106 MM.111

Tree size as % of standard or seedling stock 30 45 55 75 80 100

Support Needed Yes May May No No No

Yields a. Early b. Heavy

++++

++

++

++

-+

--

Adaptability a. Wet soil b. Dry soil c. Heavy soil d. Light soil e. Cold temperature f. Hot temperature

-+-+?+

-+++++

-+-+-+

-+-+-+

++++++

?+++++

Disease Resistance a. Collar rot b. Fireblight

?-

?-

++

-?

++

++

Spacing in Feet Between Trees for Spur Type(add 2' between each tree for nonspur typetrees) Use smallest spacing for poor soils andlargest spacing for excellent soils.

8'-12' 10'-14' 10'-16' 12'-16' 14-18' 16'-20'

Care of StockInspect your stock as soon as it to see if

proper varieties and numbers were sent. Also,check on sizes, development and condition. Theyshould arrive in a damp material, such assphagnum moss, peat moss or wood shavings. Ifyou can't plant them in 2 or 3 days, you canspray plants with water and store them in thepackage in a cool, sheltered place. If planting isdelayed, plants should be heeled in.

B. PLANTING APPLES

Mapping LocationsIt will be helpful to have a planting plan

showing where different varieties will be planted.Different varieties may need to be managed indifferent ways depending on time of ripening andsusceptibility to pests. If you do not write itdown, you will probably forget what is plantedwhere. You can put the plan in a notebook andu s e i t f o r m a k i n g r e c o r d s o f

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Planting

T Keep tree roots moist and protected fromthe drying effects of the air at all times duringplanting. Roots may be kept in water orcovered with burlap or straw. Perhaps the bestway is to lay each tree near the planting siteand cover the roots with moist soil.

T Make the planting hole large enough forroots to fan out without crowding, and deepenough so that roots are properly covered.

T Cut off all broken roots. Use a slanting cuton the underside so that the root will shedwater better and heal more quickly. Separateroots that are twisted together even if you mustremove one.

T Set standard-size fruit trees at the samelevel or slightly deeper than they were in thenursery. In planting dwarf trees, take care thatthe graft union is above ground. If it is belowground, the part above the union will developroots and destroy the dwarfing effect of therootstock.

T Incline the tree slightly in the direction ofthe prevailing wind so it will not blow over.

T Free-standing, dwarf apple trees should besupported for the first 4 to 5 years, especiallyM.9 and M.26.

T After the tree is at the proper depth and rootsare fanned out, cover roots with top soil. Packthe soil so that no air pockets are left near theroots to dry them out. After the soil has settledfor 2 to 4 months, additional soil may beneeded to level the hole.

T In spring, mound soil slightly on the edgeof the planting hole creating a saucer to allow

various things to be done. After the paper plan iscompleted, put stakes in the ground where plantswill be set.

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C. AFTER PLANTING

Site ModificationSite modification is used to create an

apple growing environment that is less favorablefor disease development and insect attacks. Sitemodifications are discussed in more detail in thesections related to specific pests and diseases.

SanitationProper sanitation is fundamental to a

sound integrated pest management program inapples. Sanitation is not limited to a specifictime of year, rather it is a year round activity.Prematurely dropped fruit, fallen leaves, andpruning trash provide food and shelter for someinsect pests and can be sources of innocluum fordiseases.

Home owners should routinely pick upand destroy fallen fruit, particularly during Mayand June. Fruit that are infested with eithercodling moth or plum curculio usually larvaedrop prematurely with the larvae still in them.This fruit should be picked up daily anddisposed of in such a manner that the larvae donot have a chance to complete their life cycle.This will help to reduce damage later in theseason.

Apple scab overwinters in the appleleaves that had fallen around the base of the treethe previous fall. Removal or destruction ofthese leaves will limit the amount of primaryinnoculum the following spring. Composting orshredding of the leaves in the late fall or earlywinter are effective methods of removing leaves.

Debris around the base of the tree andloosened bark provide protection for codlingmoth during the winter and during pupation.Debris such as piles of leaves and pruningsshould be removed during the winter and notallowed to accumulate. Sanitation is discussed inmore detail under the sections related to specificpests and diseases.

ExclusionSome diseases, especially soil-borne and

root diseases, may be brought into the plantingon transplants. Buy nursery stock fromreputable growers. Inspect all purchases forgalls, root decay, stem cankers, or insect pestsand exclude all diseased or insect-infested plantsfrom the home fruit planting.

Exclusionary devices are available toprevent injury and/or establishment by certainpests of trees and fruit. Devices, such as papersacks when placed around fruit, can protect fruitfrom feeding and egg laying by plum curculio.Paper sacks have been found to provide seasonlong control of codling moth in commercialplantings in California. Paper sacks are securedaround the fruit prior to pest activity andremoved at harvest. This has not beendemonstrated in Kentucky, but should be veryeffective particularly for plum curculio which isonly active for a short period of time in thespring.

Dormant SpraysDormant oil applications are very

important for IPM of apple insects and mites.Dormant oils help to manage many of thesepests that overwinter as eggs on the tree. Themode of action of dormant oils is suffocation ofthe eggs. Failure to use a dormant oilapplication may require additional inseasontreatments. These inseason treatments areusually more expensive and disrupt beneficialinsects that control secondary pests.

High volume and thorough coverage isessential to getting good control with dormantoils. Trees should be pruned properly to allowfor spray penetration and good coverage.Typically a dormant oil application made duringJanuary is more effective against San Jose scalethan the delayed dormant applicationrecommended for European red mites and appleaphids. A mid-winter oil application isrecommended over a delayed dormantapplication in trees where scale has been aserious problem. Oil appications are more

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Reasons for pruning include:

T Containing tree size. Since pruning is adwarfing process, it helps to keep trees moremanageable and facilitates basic maintenanceand harvest. However, excessive pruning willdelay fruitfulness and encourage vegetativegrowth at the expense of fruiting.

T Controlling tree shape. Pruning helpsdevelop a strong tree structure that willsupport a large fruit crop without breaking. Italso helps you avoid having to prop weaklimbs. If too many scaffold limbs are left inthe tree, they will be weak and will bend toomuch or will break under a heavy crop load.In addition, removing scaffold limbs withnarrow crotch angles will help reduce winterinjury to the trees.

T Controlling flowering and fruiting. Ithelps balance the tree's fruit load and reducealternate-year-bearing problems of some treefruits.

T Repairing injury. Pruning removes broken,dead and diseased limbs, which helps reducespread of disease within the tree, reduce fruitrot diseases and improve tree survival.

T Increasing light penetration, whichpromotes fruit bud initiation within the tree.Light also improves fruit coloration and sugarcontent.

T Improving air movement, which reducesdisease-favorable humidity and moistureconditions.

T Improving penetration of spray material,which helps to produce blemish-free fruit andreduces tree insect and disease problems.

effective against European red mites when timedto coincide with egg hatch. Therefore, adelayed-dormant oil application when budsshow 1/4 inch green is recommended whereEuropean red mite or rosy apple aphids havebeen a problem.

Dormant sprays are applied during thewinter or early spring, before apple buds beginto swell. Their use is described in more detail inthe sections dealing with specific disease andinsect problems.

D. PRUNINGPruning and training are two of the most

important and time-consuming practicesinvolved in growing fruit trees. Pruning shouldbegin the spring that a tree is set out. Removingsmall branches early in the tree's life is mucheasier and causes fewer adverse effects thandoing extensive corrective pruning when thetree is much larger. Since no two individuals willprune a tree exactly the same way, and no twotrees look exactly the same, understanding basicprinciples of pruning is necessary to do a goodjob. Please note the Pruning Terminologyinformation, which is at the end of this section.

Equipment For Pruning and TrainingIf you have only one or two trees, you

may only need a pair of hand shears and a smallfirewood saw. Hand shears come in basicallytwo types. Anvil pruners are the best choice ifyou want an inexpensive pair of pruners. Theirsharpened blade cuts up against a brass oraluminum plate and will slightly crush the tip ofthe cut branch. The shear type of pruners arebest if they contain high quality steel. Blades onan inexpensive pair will become splayed aftersome use and then won't do an adequate job ofcleanly cutting a branch.

Long-handled pruning shears orloppers cut intermediate sized limbs up to about1 inch in diameter. They can be found in manyshapes and forms. If you buy loppers, get a pairwith a rubber shock absorber, which makes

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extensive pruning less tiring.A small firewood saw can remove

larger limbs; however, it occasionally won't fitwhere several branches are clustered together. Asmall lightweight pruning saw is ideal forgetting into tight places. They generally have awooden handle with an 8 to 15 inch curved sawblade. Teeth are wide set with about 6 teeth perinch to enable you to cut green wood withoutclogging with sawdust. Some models can befolded and carried in a back pocket. A polepruner and/or saw can help you prune limbsthat are out of reach and can reduce the amountof time you use a ladder.

Hydraulic or pneumatic pruners andsaws work well in reducing pruning time and inreducing pruning costs in large fruit plantings.

Tree spreaders are indispensable inhelping develop a strong tree structure. Whileheavy toothpicks, clothespins and sharpenedwires may be used on small branches, usewooden spreaders on larger branches. Woodenspreaders are made in varying lengths and havenails driven into both ends with the heads cut offat an angle. In a home situation with childrenaround, these nails can be dangerous. Instead,make spreaders from lath strips with a V-notchin each end.

General Principles of PruningTypes of Pruning Cuts

Basically only two types of pruning cuts

are made in pruning, the heading-back cut andthe thinning-out cut. The heading-back cutinvolves removing the terminal portion of ashoot. It promotes branching in a 10-inch areabelow the cut. The uppermost remaining budthen grows to become the new leader andusually 2 to 4 other lateral buds below theterminal bud also grow out. Heading-back isused primarily on young trees to inducebranching where you want to strengthenscaffold limbs and to develop tree structure.

On bearing trees, very light headingpreserves flower spurs below. With increasinglysevere heading, more shoots are produced andthe number of flower spurs that are developed isreduced. Heading-back is the most drastic of thetwo types of cuts and effects of the cut areconfined to a very localized area. The use of theheading-back cut in older trees should beminimized, since it tends to reduce spurformation and fruiting.

The thinning-out cut involvesremoving a shoot at its origin. This type of cuthelps to keep the tree from becoming too bushyand causes the tree's existing framework togrow. It is used on young trees to favor thedevelopment of certain limbs and shoots and isalmost always used on older bearing trees thatneed light penetration into their interior, and noadditional branching.

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When to PrunePrune all fruit trees annually. Only

through annual pruning can we properly train atree to develop and produce maximum crops ofquality fruit. Most pruning is done during thedormant season after danger of winter injury isover, usually from February until just before fullbloom. Prune as late as possible, since pruningcauses limbs to deharden and makes the treemore subject to cold injury. Young trees(approximately 5 years or less) are much moresubject to winter injury, so save these for last.Start pruning oldest trees first in February.

Also by waiting until late winter or earlyspring to prune you can determine the amountof winter injury and prune accordingly. If a largepercentage of fruit buds have been killed, thetree may need only very light pruning. If mostbuds survived, pruning should be heavier. A treethat shows severe winter injury to woodyportions of its trunk and/or branches should bepruned very lightly or not at all in spring. Deadwood is then removed from these trees insummer when the injury can be clearly assessed.

Pruning in fall is not recommended. Itdelays development of winter hardiness and can

lead to severe winter injury, particularly onyoung trees if an early winter freeze occurs.Summer pruning is an extremely dwarfing anddevitalizing process and is restricted primarily toremoving watersprouts and suckers.

Pruning at PlantingAt planting no matter what training

system is used, the central leader of the tree isheaded back to a height of about 30 inches onone year old trees. This heading back cut willforce vigorous wide angled scaffold limbs toform within an area about 10 inches below thecut. This leaves enough room below the lowestscaffold limb for an 18 inch rodent guard.

Large trees may have lateral branchesalong their trunks. Some of these should beremoved completely, but others in desirablelocations for scaffold limbs should be headedback leaving 2 to 4 inch stubs containing one ortwo lateral buds each. The central leader shouldbe headed back at the same height as for smallertrees.

In a back yard planting the central leadermay be headed somewhat higher if this makesthe lower scaffold limbs too close to the groundfor mowing. Heading young trees when theyare planted in the spring is extremely important.

Training During the First Growing SeasonIncreased growth of the most desirable

scaffold limbs can be obtained by pinching backless desirable branches and removing suckersduring the first summer's growth. This processis usually done two or three times during thesummer.

A Central Leader Tree - is shaped just like aChristmas tree. It consists of a central leadertrunk with scaffold limbs symmetrically arrangedon it and radiating outward. A central leadertree has a maximum of strong horizontal fruitingwood and a minimum of heavy uprightstructural wood. Scaffold limbs arewell-balanced around the central leader andallow maximum interception of sunlight, as wellas fruit production along their entire length. Atree may have as many as 11 to 14 scaffoldbranches, and they should be stout enough tosupport a fruit load without propping.

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Ultimately on a mature apple tree wewould like to have a whorl of 4 scaffold limbsabout 28 inches from the ground, 4 morescaffold limbs 3.5 to 4 ft above the first whorl,and then a whorl of 3 scaffold limbs about 3.5 ftabove the second whorl. A young tree would bedeveloped with scaffold limbs between thesewhorls and these intermediate limbs would begradually taken out over a period of years as thetree gets larger and more sunlight needs to reachthe interior.

A Modified Central Leader or MultipleLeader Tree - is developed with scaffold limbsradiating out from the trunk and then at somepoint, depending on the fruit variety, the centralleader is cut out to open up the center of thetree. This form is sometimes used to trainapples, although the central leader form ispreferred.

In this type of training system, scaffoldlimbs should be spaced evenly around the treebeginning at about 28 inches from the ground.Leave about 8 to 12 inches of vertical distancebetween scaffold limbs.

Getting the desired number of scaffoldlimbs may take 3 or 4 years. As the tree getsolder, the upper center of the tree is kept prunedout to allow sunlight to reach the interior of thetree.

In the dormant season remove pinchedback branches and all lateral branches onscaffold limbs within 18 inches of the trunk. The

ball of pinched back foliage in the center of thetree may be removed at this time if scaffoldlimbs are well spread and the tree has madegood growth the first season. If not, leave theball of foliage and remove it during the nextdormant season. Remove any branches growingacross the center of the tree, toward the groundor straight up toward the sky.

Hereafter, until the tree reaches thedesired height remove branches each spring thatform on the trunk or grow across the center ofthe tree. Work on developing a series ofsecondary scaffold limbs off the main scaffoldlimbs. Shorten limbs that tend to grow morerapidly than others.

When the tree reaches the desired size(7-8 ft high), cut all branches over 7-8 ft back toan outwardly growing lateral branch to keep thetree height down. Thin out 10 to 20% ofone-year-old fruiting wood.

Pruning ObjectivesEliminate weak crotch angles. Narrow crotchangles tend to be weak because bark from bothbranches prevents the two branches fromknitting together well. These branches are onesthat split off under the weight of a heavy fruitload or in an ice storm. Wide crotch angles aremuch stronger since bark does not accumulatebetween the two branches. Thus, thinning-outcuts should be used to eliminate narrow crotchangles before branches get large.Leave the swollen branch collar. Always cuta branch at its base at the outer edge of branchbark ridge and the branch collar. These pointsdesignate the edge of the tree's natural barrier todecay. Cutting the branch flush with the treeopens up this barrier making the wound largerand more difficult for the tree to exclude decay.

While leaving the swollen branch collarto avoid a flush cut, do not leave a stub. If youleave a stub, it will either produce watersproutsor die back to the next point of branching. Astub must rot out before the tree can grow toseal over the wound. This rot often causesadditional decay in the tree, which may also

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infect fruit, resulting in storage decay.When your remove a large limb, first

undercut the limb and then saw it off past theundercut portion, to avoid tearing bark when thelimb drops off. When the limb falls off, barkwill tear to the point of the undercut. Then sawoff the stub to make a smooth cut that will healrapidly.

T Let the sun bleach and dry out areas wherelimbs have been removed. Painting cut areas orapplying wound dressings actually increasesdecay. Trees do not heal wounds, butcompartmentalize the diseased area and growover it.

T When selecting framework branches,never select one that is directly over anotherunless it is at least 24 inches above the lowerbranch. Upper branches compete with lowerbranches for sunlight and shade them out. Withcloser spacings, the top branch will receive moresunlight and will grow faster. The lower branchwill be shaded, grow slower and produce lowerquality and fewer fruit.

T After the tree has been shaped by earlypruning, the job consists mainly of pruningto keep it within bounds, removing broken anddiseased limbs, occasionally removing limbs tolet more light into the tree interior, removingwatersprouts and suckers and removing limbsthat rub together.

Pruning TerminologyBranch bark ridge: The ridge at the base of alimb's upper side, caused by bark phellogenforced to the surface. It indicates a naturalbarrier to decay on that side of a limb.

Branch collar: The raised area at the base of alimb's lower side, caused by clumping ofvascular tissue. This designates the edge of thetree's natural barrier to decay, on that side of thebranch.

Central leader: The central trunk in a centralleader pruning system, which extends from theroot to the top of the tree.

Crotch: The point at which two branches join.

Framework: Major limbs that make up a tree'sstructure and support its fruiting branches.

Graft union: The point at which the rootstock isjoined to the desired fruit variety.

Heading back: Cutting back a branch or limb,but not completely removing it.

Lateral branch: A small limb growing from alarger limb. Often used for fruit wood.

Leader: A dominant upright branch.

Primary scaffold limb: One of the major limbsarising from the trunk.

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Rootstock: The original plant that is now theroot system upon which the desired fruitingvariety has been budded or grafted.

Secondary scaffold limb: A framework limbthat arises from a primary scaffold limb.

Shoot: Current season's or one year old growth,with or without leaves.

Spur: A short shoot that is the primary fruitingstructure on apples, pears, plums and cherries.

Stub: A protruding branch left after pruning,which is the result of careless pruning. A branchshould be removed at the outer edge of thebranch bark ridge and the branch collar formaximum decay prevention.

Sucker: A vigorous shoot that arises below thebud union from the rootstock roots.

Terminal: The apex of a shoot or limb.

Thinning out: Complete removal of a branch orlimb at its point of origin.

Watersprout: A vigorous, usually undesirable,shoot arising from the trunk or scaffold limbs.

E. SUMMER CARE

Soil ManagementAn apple tree is long-lived, so give

special attention to soil management before andafter establishing the planting. Soil tests takenthe season before planting will indicate fertilizer,lime or sulfur requirements on the planting site.

Apples are often grown in a grassy areaand mulch is used at the base of the plant toimprove appearance and keep the tree healthy.For the home gardener, mulching is an excellentway to reduce weeds and to keep lawnmowersaway from the trees. Mulch should extend as farfrom the trunk as the limbs and should be 2-4

inches deep. Mulch conserves moisture, keepssoil cool, and adds organic matter. However, itmay be a hiding place for mice, and special careshould be taken to combat this pest. When youfirst use mulch, increase the amount of nitrogenfertilizer by 50% (see section on fertilizing).Organic mulches may also be usedadvantageously with any of the other soilmanagement systems. Grass clippings, hay,straw, strawy manure, sawdust, corncobs, etc.are all good mulch materials.

Fruit trees may be planted in permanentsod with cultivation around the trees. Thecultivated area may extend slightly beyond theends of branches. Cultivation must be veryshallow to avoid damaging tree roots. Thecultivated area will dry out quickly andadditional water may be necessary during dryperiods.

FertilizationBecause apples are perennials, they

require a different fertility program from that ofannual plants. In perennials, fertilizer appliedduring the current season affectswinter-hardiness and production the followingyear. In most fruit plants, nitrogen should be atits highest level during spring and summer andlow in the fall to slow growth and reduce winterinjury.

Adjust soil acidity to pH 6-6.5 beforeplanting. Base adjustments before planting onrecommendations for establishing fruit plantingsgiven in U.K. Extension publication AGR-1,"Lime and Fertilizer Recommendations." Workfertilizer into the soil before planting rather thanplacing it in the hole at planting. Roots thatdirectly contact undissolved fertilizer may beburned.

During subsequent seasons, basefertilizer applications on plant growth rate andcondition. If average new terminal growth is lessthan 12 to 15" for mature trees or 24 to 30" for1 to 3 year old trees apply 1/4 lb ammoniumnitrate (½ lb granular fertilizer is equal toapproximately 1 cup) per tree per year of age in

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February. If terminal growth exceeds theamount listed, reduce the nitrogen.

Fruit crops grown in the lawn oftenreceive enough nutrients from the lawn'sfertilizer. In this case, determine if additionalfertilizer is needed based on terminal growth.

F. THINNING FRUITS ON TREESWhy?

Apple trees often set more fruit thanthey can mature to a desirable size. Thissituation can be remedied by hand-thinning orpulling excess fruit. Nutrients are then utilizedto produce fewer but larger, higher quality fruit.The total usable production of a properlythinned tree will be almost as great as anunthinned one. Apples spaced an average of 6 to8 inches apart on a limb will have enough leavesneeded to properly size the fruit. Apple fruitsneed to be thinned almost every year. Someapple varieties get into an alternate bearingcycle. In these instances, a lot of fruit would beremoved during the heavy bearing year and nothinning would be done during the lightproduction year.

How Much?Don't be alarmed if you must remove as

much as two thirds of the immature apples froma tree. The important thing is the number youleave on the tree, not the number you remove.The general recommendation for fruits perbranch length is 1 fruit per 6-8 inches of branch.If a branch measures 18 inches, 2-3 fruit shouldbe left on it. If a branch measures 60 inches, 8-10 fruit should be left on it.

How?When thinning, try to pull off damaged

fruit, break up clusters and space the load asuniformly as possible over the tree. Reduceclusters to one fruit and space these uniformlyover the tree. Don't shake apple branches to thinthe fruit, because you will remove the largestfruit and bruise what is left.

When?There has been much discussion about

when to thin a fruit crop. Apples have 3 periodswhen some immature fruit drops from the tree.June drop is the last one and many growers feelthat thinning should follow this drop. However,if a heavy bloom has coincided with goodweather so that bees worked the blooms,chances are that relatively few fruit will dropfrom the tree. In this situation, heavy thinning isrequired in June. Early varieties should bethinned earlier. Because early varieties matureover a short time, early thinning gives them abetter chance for sizing by reducing nutrientcompetition.

Irrigation of FruitsIrrigation, especially for small fruits, will

increase production of large, high quality fruitsmore than any other practice. You can getexcellent results with an ordinary lawn sprinkleror soaker hose. In general, if rainfall is less thanone inch per week, add the amount of irrigationwater required to bring the total to one inch.Trickle or drip irrigation is also very effective.

G. WINTERIZING FRUIT TREESExamine the soil around the base of the

trees for depressions, which can trap water inthe root zone. In addition, ice in depressionsadjacent to the trunk or roots can physicallydamage the plant. The ideal topography is soilsloping away from the trunk so that water willdrain off.

Remove any vegetation within 12 to 14inches from the trunk to discourage rodentssuch as voles and mice from nesting and feedingon the trunk. Put commercial or homemadetreeguards (cylinders of 1/2 inch hardwarecloth) around the trunk to prevent rodents fromdamaging it. Tree guards should be largeenough in diameter to allow for growth andshould be 18 inches high to discourage rabbits.Push the treeguard an inch or so into the groundto discourage tunneling voles. Treeguards are

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Winter damage can usually be attributedto:

T too much or too little moisture;

T colder mid-winter temperatures than theplant can withstand;

T fluctuating temperatures, especially in latefall and early spring, that reduce plant

even more important when mulch is used nearthe base of the plant.

A common winter problem on youngapple trees is sunscald injury or injury to thesouthwest side of the trunk. This winter injuryoccurs because of rapid fluctuations intemperature, as on cold days when the sun heatsthe southwest side of the tree and then passesbehind a cloud or is blocked abruptly.Subsequent rapid temperature drops cause thebark to split and separate from the tree.

This injury can be reduced by paintingthe tree trunk from the ground to a height of 36inches or so. Interior white latex paint reflectsthe sun's heat and is least damaging to the tree.Painting is usually done after frost and beforeonset of extremely cold temperatures.

While we can do little to control theweather's effect on hardening or dehardening,we can alter the plants environment to avoiddirect injury from cold, and we can avoidcultural practices known to delay or reduce thelevel of hardening. One method that alters theplant's environment is mulching. It helps protectplants from winter injury in two ways: itprotects shallow-rooted plants from extremelycold temperatures; and it avoids fluctuatingmoisture levels in the soil that can predisposethe plant to injury from future cold stress.Mulch also slows soil warming in spring,preventing dehardening and reducing damagefrom occasional sudden drops in temperature.The plants which bloom earliest suffer mostfrom late spring frosts.

Cultural practices that affect the plant'scapacity to survive winter include pruning,fertilization and watering. Anything thatpromotes excessive growth will normallydecrease a plant's capacity to survive winterstresses. Avoid any cultural practice thatoverstimulates the plant so that it keeps growingin the fall; avoid over fertilizing, excessivewatering and early fall pruning. Ideally, the plantshould grow slower in late summer and earlyfall. Twig dieback and bark cracking will beworse on trees that continue to grow.

While too much watering can causewinter injury, adequate water is needed toprevent injury from dying caused by coldtemperatures and winter winds. If you can wateryour plants, water them when needed, especiallyduring summer, September and October, whichare dry periods.

A healthy fruit planting will be able tosurvive winter stress better than a neglected oroverly-vigorous one. Late fall is a pleasant timeto be out in the yard doing tasks necessary tohelp your plants get through the winter. While inthe yard, observe and correct any potentialproblems.

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III. DISEASE MANAGEMENTIn a general way, apple growers need to

be aware that apple diseases are only possiblewhen susceptible apples are exposed to virulentpathogens (usually microbes) underenvironmental conditions favorable for infectionand disease development. Knowledge of howthese three factors interact are helpful forgrowers attempting to understand and controlapple diseases.

A. APPLE SCAB Apple scab is the most consistently

serious disease of apples in Kentucky. Thisdisease has the potential to cause serious fruitlosses and to seriously weaken trees throughdefoliation every year, and should, therefore, bemonitored closely.

SYMPTOMS: Scab infections are mostprominent on the leaves and the fruit. On theleaves, early infections appear velvety,olive-green and become puckered with time.Severely diseased leaves may become distortedor turn yellow and fall from the tree. Spotsinitially appear on the underside of leaves, so besure to look there; later, spots also appear onthe upper leaf surface, where they are somewhateasier to detect. (See Apple Disease I picturesheet, plate #8.)

Fruit spots resemble leaf spots whenyoung, but eventually become brown or black,develop a corky ("scabby") appearance, andfrequently become cracked. Infections may bemore prevalent near the blossom end.

DISEASE CYCLE: The scab fungusoverwinters in diseased leaf litter on the ground.In spring, the fungus produces windblownspores, which can be carried to susceptible appletissue and cause an initial (primary) infection,given the proper temperature and moistureconditions. If primary infection occurs, newspores are produced; this is the velvety growth

on leaf and fruit spots. These new spores canthen be splashed by raindrops to nearby tissuesand cause repeating (secondary) infections therest of the season when the weather isconducive. The cycle is completed whendiseased leaves eventually fall to the ground.

As can be seen from the accompanyingchart, called Mills' table, infection andincubation periods are predictable, being basedupon average temperatures and the number ofhours that leaf surfaces remain wet.Consequently, a knowledge of recent weatherwill indicate when new scab infections might beobserved. Also, note that secondary infectionscannot develop unless primary infections occurfirst, during the early season.

Disease prediction instruments such asthe Envirocaster, or Metos predictor whenplaced in the orchard, use Mills' Table tocompute the disease prediction. Suchinstruments offer the grower and IPM scout aprecise means of managing apple scab diseases.The advance of new fungicides capable of"eradicating" already progressing infections upto 4 days after a wetting event makes apple scabmanagement using predictive instruments apractical activity for commercial growers.

SCOUTING: Lesions (spots) can first appearabout 10-14 days after bud break. Earlyinfections are most likely to be noticed on theflower bud leaves (sepals). Recall also that theundersurface of leaves may become spottedbefore the top surface. Examine 20 leaves oneach of 5 limbs per tree and record the numberof leaves showing any scab lesions. After fruithas set, make leaf observations, and alsoexamine 20 fruit on each tree showing any scablesions

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Table 3. MILLS' TABLE Approximate number of hours of wetting required for primary apple scab infection at different air

temperatures and the length of time required for secondary spore development.

AveTemp NF

Degree of Infection (hrs)a

Light Moderate Heavy DaysIncubationb

78. . . . .13 17 26 77. . . . .11 14 21 76. . . . . 9.5 12 1963-75. . . . . 9 12 18 9 62. . . . . 9 12 19 10 61. . . . . 9 13 20 10 60. . . . . 9.5 13 20 11 59. . . . .10 13 21 12 58. . . . .10 14 21 12 57. . . . .10 14 22 13 56. . . . .11 15 22 13 55. . . . .11 16 24 14 54. . . . .11.5 16 24 14 53. . . . .12 17 25 15 52. . . . .12 18 26 15 51. . . . .13 18 27 16 50. . . . .14 19 29 16 49. . . . .14.5 20 30 17 48. . . . .15 20 30 17 47. . . . .17 23 35 c

46. . . . .19 25 38 45. . . . .20 27 41 44. . . . .22 30 45 43. . . . .25 34 51 42. . . . .30 40 60

aThe infection period is considered to start at the beginning of rain. bApprox. no days required for secondary spore development after primary infection. cData are incomplete at low temperatures. *From W. D. Mills, Cornell University.

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SCAB MANAGEMENT:

T Plant Scab-immune trees.

T Remove nearby landscape trees or treebranches which shade the apple tree.

T Thin apple tree branches during thedormant pruning operation and removesuckers during summer pruning.

T Rake up and destroy all fallen leaves fromthe previous season.

T If a protectant fungicide is used, apply onlyat green tip, tight cluster, pink, petal fall, andten days later.

T Use temperatures and leaf wetness withMills' Table to determine when infectionshave occurred.

T If a systemic fungicide is available, applyonly after a leaf wetness and infection event.

T Construct a clear plastic canopy over thetree to prevent leaves from becoming wetfrom bud break to ten days after bloom.

B. FIRE BLIGHT

Although not a serious problem everyyear, fire blight is a disease which can "explode"with devastating consequences under the properconditions. Consequently, fire blight should bemonitored closely.

SYMPTOMS: Infection first occurs aroundbloom. Infected blossoms appear water-soakedand turn brown or black. The infections maythen spread through the blossom-bearing stem(pedicel), turning it black, and into the spur ormain branch to form a canker. As young shootsbegin to develop, they may also becomeinfected. This "twig blight" phase of the disease

begins at the succulent growing tip and movesdownward. Infected twigs turn dark brown andbecome hook-shaped, like the top of a cane.The leaves on infected twigs or spurs then turnbrown and die and appear as though they havebeen scorched by a fire, but remain attached.(See Apple Disease II picture sheet, plate #7.)

If the fire blight bacteria spread into themain branches, they may cause a canker todevelop. Such cankers often appear outlined bycracks in the bark at their margins. Fruit mayoccasionally become infected; these generallyturn brown to black at the site of infections, andexude droplets of milky or amber ooze. In fact,the presence of ooze on the surface of anydiseased tissue, especially during humidweather, is a good diagnostic sign for fire blight.

DISEASE CYCLE: The fire blight bacteria,which overwinter in the margins of limb andtrunk cankers formed the previous season, beginto multiply rapidly as temperatures warm in thespring to about 600F or higher. As the bacterialpopulation increases, oozing sticky droplets willbe formed on the surfaces of cankers. Thebacteria from these droplets are then spread toopen blossoms by insects, where they may causeinfections and continue to multiply and ooze.Further spread to additional blossoms or twigsis accomplished by insects and splashing orwindblown rain.

SCOUTING: Be especially alert for theblossom blight and spur blight phase of thisdisease when the weather is warm (65-800F),humid, and rainy during the bloom period;similarly, be especially alert for the twig blightphase if these conditions prevail while activeshoot growth is occurring. All apple varietiesare at least partially susceptible to fire blight;however, the following varieties are highlysusceptible and should be watched closely:Beacon, Fuji, Gala, Idared, Jonathan, Lodi,Paulared, Rome, Tydemans Red, Wealthy,Y e l l o w T r a n s p a r e n t a n d Y o r k .

During the bloom period, examine 20

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blossom clusters on each of 5 limbs per tree andrecord the number of fire blight strikes. Afterthe bloom period, similarly note the number ofstrikes per 100 spurs and 100 terminal shoots oneach tree examined. Continue monitoring untilthe terminal shoot buds have set. When scoutingfor fire blight, be sure to check for the presenceof blighted suckers arising from the rootstock.Blighted suckers can quickly lead to the death ofthe tree.

USING THE MARYBLYT COMPUTERPROGRAM TO AID IN APPLE FIREBLIGHT CONTROL: An approach tounderstanding and thereby attaining bettercontrol of fire blight is presented in a computerprogram called MARYBLYT developed by PaulSteiner at the University of Maryland and GaryLightner of the USDA/AFRS, Kearnysville,WV. MARYBLYT can be run in a DOScompatible home or office computer. Whenusing MARYBLYT in an IPM program,growers are required to record daily high andlow temperatures, rainfall, hail, frost, and treedevelopment stage to be entered into acomputer program file for their orchard. Thecomputer calculates when fire blight infectionshave occurred, when they are likely to occur,based on weather forecasts, and furthermore,predicts when visible symptoms would appear inthe days following infection.

MARYBLYT predicts four distincttypes of fire blight: blossom, canker, shoot andtrauma blight. Disease development ismonitored using current weather andphenological (seasonal tree development)information to operate three cumulative time-temperature "clocks". There is an "appleclock," a "disease clock" and a "pathogen clock"which keep track of tree, canker disease, andpathogen development to make predictionsabout fire blight disease. Blossom blight involves direct infections ofopen flowers and killing of the spur. The sourceof inoculum is overwintering cankers in andaround the orchard. Early symptoms oftenshow ooze droplets or browning of blossom

pedicels. The infection of a single flower in acluster usually kills the entire spur. In laterstages bacteria invade the supporting twig,causing a canker that girdles the twig, resultingin the loss of other nearby spurs. Canker blight involves the renewal of infectionactivity at the margins of overwintering fireblight cankers. Some cankers may expandlaterally to girdle limbs, causing their suddendeath.Shoot blight, or twig blight, is the most visibleand damaging phase of fire blight. Primaryshoot blight involves direct infections ofvegetative shoot tips. The top 3 leaves ofgrowing shoots are most susceptible. Inoculumfor shoot blight comes from earlier blossom orcanker blight infections. If these sources arenearby, early shoot blight can usually beforecast. Early shoot blight symptoms show aslight wilt of the shoot tip, sometimes with oozedroplets visible on the stem. This is soonfollowed by leaf and shoot browning and deathwhich proceeds down the shoot. Infections ofshort shoots are more likely to lead to cankerdevelopment on the supporting limb. Trauma blight is the sudden, widespreadoccurrence of fire blight on many tissuesfollowing hail, severe wind or late frost damagewhen the populations of the bacteria on thefoliage are high.

The MARYBLYT screen display showsrisks of infection (low to high) and decisions onwhether to spray for blossom blight are basedon these risks. A "predictions" option usesforecasted weather information to determinerisks for one or more days in advance. Growerscould use the MARYBLYT risk warning todetermine whether or not to spray.

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Table 4. MARYBLYT

DATE PH HI LO WET T S NOTE AVG EIP BHWTR BBS CBS SBS TBS

3/31 D 46.0 40.0 0.00 4/ 1 GT 59.0 42.0 0.00 4/ 2 GT 67.0 38.0 0.50 4/ 3 GT 71.0 49.0 0.00 4/ 4 GT 75.0 58.0 0.00 4/ 5 TC 70.0 49.0 0.00 4/ 6 TC 76.0 42.0 0.00 4/ 7 TC 73.0 50.0 0.20 4/ 8 TC 75.0 48.0 0.35 4/ 9 PK 77.0 50.0 0.00 4/10 PK 81.0 48.0 0.00 4/11 B 78.0 49.0 0.00 4/12 B 84.0 55.0 0.00 X 4/13 B 70.0 60.0 0.55

43.0 0 0 0 0 0 50.5 0 0 0 0 0 52.5 0 0 0 0 0 60.0 0 0 13 0 0 66.5 0 0 42 0 0 59.5 0 0 55 0 0 59.0 0 0 65 0 0 61.5 0 0 81 0 0 61.5 0 0 CMI 0 0 63.5 0 0 38 0 0 64.5 0 0 45 0 0 63.5 39 +--+M 0 52 0 0 69.5 124 ++-+H 0 64 0 0 65.0 139 ++++I 0 72 0 0

A - ADD DATA M - MODIFY DATA G - GRAPH DATA P - PRINT DATA H - HELP X - PREDICTIONS V - VIEW DATA T - MODIFY THRESHOLDS E - EXIT

CHOICE =

In years with low disease pressure, growershave saved one or more streptomycin sprays byfollowing the MARYBLYT recommendations.

The MARYBLYT program also informsthe grower when an infection has occurred. Bycontinuing to enter weather data, the programalso predicts or alerts the grower when certainsymptoms such as blossom blight or shoot blightare going to occur. If infected spurs areremoved immediately when symptoms just beginto appear, further spread of the disease can bestopped, and this reduces later infections oftwigs and branches. Growers with laboravailable could use this feature of MARYBLYTfor timely pruning.

Using the MARYBLYT computerprogram. Using MARYBLYT from your harddrive or a floppy disk, activate the file MB.EXEand continue past the title screen as directed.From this point, procedures and features willvary depending on the version of MARYBLYTused. A file menu and directory screen presentschoices, the most important of which are to starta new file, to get an existing file (to add to orreview), and to exit. Other choices mightinclude an explanation of fire blight andMARYBLYT, and various file operations

including deleting, adding, changing the name,and printing a list of files. The screen mightlook like this:MARYBLYT, Version 2.1[Copyright 1989, All Rights Reserved]

A. Fire Blight control and the MARYBLYTProgram

B. Start a New File

C. Retrieve a File

D. Exit

At this stage it would be wise for theuser to explore one or more of thedemonstration files provided with theMARYBLYT program. They may be listed asa numbered file on this menu screen, or as anumber in the list of files on the diskette orcomputer subdirectory. After some practice, theuser can begin to create files relating to theirown orchard or orchard blocks.

When a grower creates a new file, it willbe given a short name and in some cases thevariety, orchard name, and year. The program

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FIRE BLIGHT MANAGEMENT:

T Select fire blight disease-tolerant varietiesand rootstocks.

T Sanitation - this involves pruning out lastyear's infections and any dead wood in thewinter. Prunings must be removed from theapple planting and destroyed.

T Faithfully record temperatures, rain, andtree growth stage in the spring.

T Use MARYBLYT to determine whensymptoms will appear.

T Eradication - this means plucking out allinfected fruit spurs when symptoms firstappear on the one or more of the fadedflowers or fruitlets in the spur.

T Although commercial growers use theantibiotic streptomycin, it is probably not agood idea for urban situations.

T Use MARYBLYT to determine when tospray, if sprays are used.

T Construct a clear plastic canopy over thetree during bloom to prevent movement ofbacteria into the flowers by rain.

immediately calls for a beginning date, usuallysometime in March near the end of the dormantseason, the high and low temperatures for thatdate, and the rainfall or other weather events forthat day. Once this data is entered, a file for theorchard or block in the orchard is begun and anew chart appears on the screen (Table 4).

This chart is divided; the left portion isdata entered by the grower relating to date, treegrowth stage, high and low temperature,rainfall, trauma events, sprays, and other notes.The user then follows directions from a lowersection of this chart to add, modify, graph, view,and make predictions from data. The rightportion of the screen presents the computercalculations of average temperature, epiphyticinoculum potential, risk factors and potential,blossom blight symptoms, canker blightsymptoms, shoot blight symptoms, and traumablight symptoms. The chart on the computerscreen might appear as follows:

It is important for the grower to begintaking records while the trees are still dormant.Temperatures leading up to bloom helpdetermine growth of the fire blight bacteria inthe old cankers and how many bacteria areavailable for infection. The most vulnerablestage for the apples is the bloom period. This isalso the only time chemical control can be usedto reduce infection. Growers could enter dataweekly from dormant to tight cluster stages, butbeginning with pink, data should be entereddaily to track fire blight progress.

In this example, the (+) and (-)designations appear at bloom. The headingBHWTR stands for bloom, heat (accumulated),wetness, temperature (for that day), and risk ( += low, ++ = medium, +++ = high, and ++++ =infection). On April 11, in this example, the riskwas medium because only two of the fourcriteria needed for infection were met: the treeswere in bloom, and the temperature that daywas suitable for infection. On April 12,accumulated heat had built up so that bacterialinoculum (EIP) crossed a threshold of 100, andthe risk was high, but still no infection occurredbecause the rain or heavy dew needed to wash

the surface bacteria into the base of the bloomsdid not occur. On that day, the X appearing inthe left part of the chart told the grower to lookat the weather forecast and if rain was predicted,to spray if needed. On April 13, the rainprovided the fourth risk factor and infectionoccurred.

As data are added to the chart afterbloom, growers will be alerted to the date offirst appearance of fire blight symptoms in theblossoms and the shoots. Careful pruning ofinfected fruit clusters can reduce further spreadof the disease. Additional details aboutMARYBLYT can be found in the help menu of

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POWDERY MILDEW MANAGEMENT:

T Sanitation - this could involve pruning outbadly infected shoots.

T Fungicide sprays can be used for powderymildew control.

T Thin branches of the apple tree during thedormant pruning operation, remove suckersduring the summer.

T Remove nearby landscape trees or tree

the program.

C. POWDERY MILDEW

SYMPTOMS: The most obvious sign ofpowdery mildew is the presence of a whitish,powdery or felt-like growth on the leaves, firstalong the margins and lower surfaces, andeventually over the entire leaf surface. Infectedleaves are distorted, becoming narrow, cuppedtowards the middle, and brittle. Fruit on heavilyinfected trees may become severely russeted.

DISEASE CYCLE: The powdery mildewfungus survives the winter within buds whichbecame diseased the previous summer. Whenthese buds open in the spring, the fungusresumes growth in the newly expanding leavesand produces the white, powdery spores whichgive the disease its name. These spores are thenblown by the wind to emerging tissue andproduces secondary infections until tree growthstops or temperatures become limiting. (SeeApple Disease II picture sheet, plate #4.)

Disease development, although rapidbetween 60-800F, is slow both between 40-500F,and at temperatures above 900F. High relativehumidities favor disease development; however,rain and dew are not required for sporemovement or for infection to take place.

SCOUTING: Powdery mildew is most likelyto be a problem on highly susceptible varieties,including Jonathan, Rome, Cortland, Baldwin,and Idared. Disease pressure is also likely to behigher in seasons following a mild winter wherefungal survival is greatest.

Record the number of terminal shootsshowing powdery mildew infections out of 100observed on each tree (20 per limb x 5 limbs).Begin monitoring at shoot emergence, andcontinue until terminal growth has ceased.

D. RUST DISEASES

Three different rust diseases can occuron apple. However, it is not necessary todistinguish the subtle differences between theserusts for the purposes of scouting, since thedisease cycles and control programs are similarfor each. SYMPTOMS: Small pale yellow spots appearon the upper surface of infected leaves shortlyafter bloom. These spots gradually enlarge upto 1/4" in diameter, depending upon the applevariety and the number of spots per leaf, andbecome bright yellow-orange in color. By earlyor mid-summer, yellow spots will also bepresent on the lower leaf surface; from thesecome small, orange-yellow tubular fruitingbodies which eventually project downwards. Asthe tubes mature, they split towards the baseinto narrow strips and curl back on themselvesto form cup-like structures. Within thesestructures a mass of light brown spores cannormally be seen with a hand lens (10x).Heavily infected leaves may fall off the tree.(See Apple Disease I picture sheet, plate #10.)

Fruit spots usually appear near theblossom end, and may be of two types: 1) spotsthat are similar in color to the leaf spots, butlarger (up to 3/4" in diameter), which may be

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CEDAR APPLE RUSTMANAGEMENT:

T If there are no cedars or junipers within200 yards of the apples, rust disease will notbe a serious problem.

T Remove and destroy susceptible cedars andjunipers if you can.

T Remove and destroy galls on susceptiblecedars and junipers.

outlined by a dark green border; 2) spots thatare dark green and sunken. Fruits with the latterinfection usually become puckered at theblossom end while the fruit is still an inch or lessin diameter. DISEASE CYCLE: Spores produced in thecup-like structures on the lower surface ofinfected apple leaves become wind-dispersed,and infect nearby cedar or juniper trees duringthe summer and fall. The rust fungus thengrows and survives two succeeding winters ingalls which are formed on infected cedars.When apple buds are in the pink to early bloomstage, the fungus produces spores upon thecedar galls, and these spores are blown to appletissue, where they infect and complete thedisease cycle two years after it began. Theinfection period for apple usually ends about 30days after bloom. Unlike apple scab or fireblight there is no apple-to-apple (secondarycycle) spread of disease.SCOUTING: Apple varieties vary greatly in

their susceptibility to rust. Be alert for leaf andfruit infections on Prima, Sir Prize, Lodi,Jonathan, Rome, Wealthy, and York Imperial.Also, look for fruit infections on Cortland,Golden Delicious, McIntosh, Red Delicious,Stayman, and Winesap.

For each tree record the number ofinfected leaves per 100 observed (20 per limb x

5 limbs). Also, examine 100 fruit per tree andrecord the number with at least one rust spot.

If you can see cedar trees near theorchard, look for the presence of the orangecedar galls from pink bud to 30 days afterbloom. Note your findings on the scoutingform.

E. FROGEYE LEAF SPOT

The fungus which causes frogeye leafspot also causes a canker disease on limbs andtwigs, and "black rot" on the fruit later in theseason. These diseases are more likely to be aproblem on old trees than on young trees.

SYMPTOMS: Small purple specks typicallyappear 1-3 weeks after petal fall. These specksthen enlarge to 1/8" - 1/4" in diameter andbecome brown with a purple margin. Olderspots become irregularly shaped or lobed, retaintheir purple margin, and appear brown with alight colored center. Small black dots mayappear in the light centers of older spots on theupper leaf surface. Heavily infected leaves mayturn yellow and fall off, especially on the varietyJonathan. (See Apple Disease I picture sheet,plate #4.)

DISEASE CYCLE: The fungus overwinters indead bark and mummified fruit. Spores areprimarily dispersed in splashing rain; thiscommonly results in the development ofcone-shaped zones of infected leaves beneaththe source of spores (e.g., fruit mummieshanging in the tree, or dead twigs and branches).Although spores may be released during rainyperiods throughout the season, leaf infectionsoccur primarily around the time of petal fall.Warm temperatures (minimum 600 F, optimum75-800 F) and adequate moisture are necessaryfor infection to occur. SCOUTING: Examine 100 leaves from eachtree scouted (20 leaves per 5 limbs) and recordthe number showing at least 1 spot. On your

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FROGEYE LEAF SPOTMANAGEMENT:

T Prune out all cankers and dead wood duringthe dormant pruning operation.

T Remove and destroy mummies (shriveled

COLLAR ROT MANAGEMENT:

T Provide good drainage. Underground tilingwill help improve internal drainage of heavysoils.

scouting form, note the presence of fruitmummies and dead wood above zones ofinfection. Black rot cankers often form inbranches that were infected with fire blight theprevious season. From records or from thegrower, note whether or not fire blight wasserious the previous season. Note leafyellowing and leaf drop if it occurs.

F. COLLAR ROT

Collar rot caused by various species ofPhytophthora is impossible to positivelydiagnose without laboratory culturing.However, the grower can identify trees whichmay be infected, and deliver appropriate samplesto the County Extension Office.

SYMPTOMS: The symptoms of collar rot areoften similar to those caused by any agent whichinterferes with part or all of the tree's root ortrunk system (rodents, soil compaction,mechanical injury, canker diseases, fire blight,etc.). Affected trees may exhibit poor terminalgrowth; have small, chlorotic leaves; and/or wiltand eventually die. Trees collapsing as a resultof collar rot will be largely or completely girdledby a zone of dead inner bark just beneath thesoil line. Bark discoloration sometimes extendsabove the soil line as well. Collar rot is mostcommon on MM.104 and MM.106 clonalrootstocks, although all rootstocks are at leastpartially susceptible. (See Apple Disease IIpicture sheet, plate #5.)

DISEASE CYCLE: The collar rot funguspersists for long periods in diseased host tissueor as resting spores in the soil. When the soilbecomes saturated with water, the fungusproduces small swimming spores (zoospores),which are chemically attracted to plant roots.Spores may also be carried by water as it drainsdown a slope and through the soil profile. Uponcontacting a root or the trunk, the spores maygerminate and infect. Both of these processesdepend upon the susceptibility of the rootstock,and how long the soil remains excessively wet.Spore production and infection is most commonin the spring and the fall.

SCOUTING: Observe and note the location ofany weakly-growing or collapsing trees. Notethese trees especially if they appear to begrowing in a low-lying or poorly-drained area.Gently dig the dirt away from a portion of thecrown (trunk/root area) and check to see if theinner bark is still alive. If so, it will appeargreen and the wood just inside the bark will befirm and white with no discoloration beingevident.

To collect a sample, dig a shallow holewithin the drip line of the tree, and put somemoist soil and segments of roots into a plasticbag. If the crown or lower trunk appearsinfected, remove a few pieces of inner bark fromnear the margin of the infected region, and placethem in a plastic bag with moist soil. It isimportant to keep samples cool and avoidplacing bags in direct sunlight before they aredelivered.

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APPLE CANKER MANAGEMENT:

T Prune out and destroy all cankers and deadwood from the tree.

T Remove prunings from the area and

G. FUNGAL TWIG AND LIMBCANKERS

In addition to fire blight (caused by abacterium), twig and limb cankers are caused byseveral different fungi. It will not be necessaryto determine the actual cause of cankers otherthan fire blight; however, it is important to notethe occurrence of cankered limbs when they areobserved.

SYMPTOMS: Generally, cankers will appearas small to large sunken areas on twigs, limbsand/or tree trunks. Depending upon the causeof the cankers, the sunken areas may exude aliquid or develop sporulating structures which inturn exude a gelatinous material laden withfungal spores. This is especially true duringhumid, rainy weather. Cankers may becomecracked or appear to blister in a way which isnot characteristic of "normal" apple bark. Manytimes cankers will be associated with lenticels ortree wounds, especially those resulting fromimproper pruning techniques. Additionally,healthy wood bordering cankered tissue willoften be swollen with callous tissue as the treeattempts to "heal" cankered wood. (See AppleDisease I picture sheet, plate #11 and AppleDisease II picture sheet, plate #1.)

DISEASE CYCLE: Canker-causing funginormally overwinter in diseased or dead woodon the tree, and produce and disseminate sporesduring rainy periods in the growing season.New infection sites then become sources ofadditional spore production. Weakened orpoorly-growing trees are especially susceptibleto fungal canker diseases.

SCOUTING: A quantitative assessment ofthese diseases is not required; rather, be on thelookout for twig and limb cankers as you scoutfor leaf and fruit diseases, and record theiroccurrence in the comments section of yourscout form.

SUMMER FRUIT ROTS

Several different rots can occur on applefruits, especially as they approach maturity. Thefollowing are the most common and important"summer rots" which occur in Kentucky.

H. BLACK ROT

SYMPTOMS: Infections are usually notapparent until fruit begin to ripen. The diseasemay first be noticed as a brown to black spot atthe blossom end of the fruit, or around a wormhole or some other wound. Usually, only ONEspot appears per fruit. This is a characteristicwhich helps distinguish black rot from someother fruit rots.

As the infected area enlarges, a series ofbrown or black concentric rings sometimesdevelops, producing an alternating "bulls-eye"or target-shaped pattern. Small black dots willfrequently be seen within older rotted areas.The infected tissue remains firm as the rottedarea expands throughout the entire fruit. At thispoint the whole fruit typically turns black. Suchfruit will eventually shrivel and harden intomummies which remain attached to the tree andbecome a source of spores for future infection.(See Apple Disease I picture sheet, plate #4.) DISEASE CYCLE: Same as "Frogeye LeafSpot", discussed previously.

SCOUTING: For each tree observed record thenumber of fruits with black rot per 100examined (20 fruit per 5 limbs). Note the

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presence of mummified fruit in the tree in thecomments section of the form. This disease ismore likely to occur in old and in poorly prunedtrees that have poor air and light penetrationthan in young trees.

I. BITTER ROT

SYMPTOMS: One to several small browncircular spots may first appear any time afterfruit are half grown. These spots expand rapidlyin warm weather, becoming dark brown or blackand somewhat sunken in the center(saucer-shaped). After the spot has enlarged toabout 3/4" in diameter, a number of slightlyraised dark "cushions" appear near the centers.As the spots continue to enlarge, these cushionsfrequently radiate outward in rings to givetarget-shaped appearance. In warm, humidweather, masses of slimy salmon-pink sporesmay be seen oozing from the cushions. If warm,moist weather prevails, several spots mayexpand and fuse together to rot the entire fruit,(see Apple Disease I picture sheet, plate #2.)

DISEASE CYCLE: The bitter rot funguspersists between crops in partially mummifiedfruit on or beneath the tree, or in dead wood.Initial infection can occur anytime that warm(about 700 F or higher), rainy weather occurs.The salmon-pink spores are then produced asthe fruits approach maturity and the infectedregions expand. These spores are subsequentlysplashed onto healthy fruits by raindrops, andcan cause a rapid secondary spread of diseaseunder warm, humid conditions. Pruning, treeshape and weed control will effect the degree ofseverity.

SCOUTING: Record the number of fruits withbitter rot per 100 examined from each tree. Thisdisease can be distinguished from black rot bythe slimy salmon-pink spores oozing fromcushions (use a hand lens to see), as well as theappearance of saucer-shaped depressiontowards the center of each spot. The presence

of more than one spot per fruit, and their lack ofconsistent association with the blossom end orwounds are other characteristics which maydistinguish bitter rot lesions from those of blackrot. In addition, bitter rotted tissue can becleanly separated from healthy tissue using aknife to give the appearance of an inward cone.This is not possible in fruit with black rot.

J. SOOTY BLOTCH/FLYSPECK

Sooty blotch and flyspeck are twodistinct diseases, caused by different fungi.However, because both diseases usually occurtogether, and because their disease cycles andcontrol procedures are similar, the two diseasesare frequently "lumped" into a single diseasecomplex. SYMPTOMS: Sooty blotch, as its nameimplies, appears as sooty brown or blackblotches on the surface of nearly-mature apples.Blotches vary greatly in size, but may be 1/4" indiameter or larger. Several blotches maycoalesce to cover relatively large areas of thefruit.

Flyspeck appears as a group of tiny,distinctly defined black dots, with several to 50or more individual dots making up a singlecluster. A number of different clusters may befound on a single fruit. (See Apple Disease Ipicture sheet, plate #5.)

DISEASE CYCLE: Both fungi overwinter onthe twigs and branches of many wild woodyplants, in addition to apple. Spores are producedand blown or splashed onto fruit during rainyperiods from May onwards; however, thediseases develop most rapidly during relativelycool, humid weather. Practically no fungusgrowth occurs at temperatures above 850F;consequently, infections which are initiated inlate spring may not become evident until theweather turns cool in the fall when fungi resumegrowth. Disease outbreaks are most likely to besevere when cool wet springs are coupled with

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SUMMER FRUIT ROTMANAGEMENT:

T Prune out cankers and dead wood in thetree and destroy the prunings.

T Remove and destroy all mummies andinfected fruit.

T Summer pruning by removing watersprouts will help improve air movement andreduce disease.

T Remove and destroy weeds, undergrowthand brush from near the orchard; these plantsmay harbor pathogenic microbes.

T Protectant fungicides can be used.

T Fruit covers such as paper or plastic bagsmay help in disease control by excludingfungal inoculum. Fruit covers are an untriedpractice and may or may not work.

later summer rains and cool weather prior toharvest.

SCOUTING: From each tree observed recordthe number of fruits per 100 examined which areinfected with sooty blotch/flyspeck. Of thoseinfected, rate the average or typical diseaseseverity as light ( < 5 % of the apple surfaceblemished), moderate (5-20% blemished), orsevere (> 20% blemished).

K. WHITE ROT

White rot is also referred to as Bot rot orBotryosphaeria rot.

SYMPTOMS: Fruit lesions begin as small,often circular, slightly sunken tan spots, whichmay be surrounded by a red or dark purple halo.As lesions expand, the rotten area extends in acylindrical manner toward the core. Underwarm conditions, the rotted areas are usuallysort, watery, and clear to tan in color. Scatteredclumps of dark fungus dots develop on the fruitsurface. The decay may progress until the entirefruit is rotted at which time the fruit may dropor hang on the tree as a mummy. The white rotfungus may also cause twig and branch cankers.

DISEASE CYCLE: Similar to black rot, thewhite rot fungus overwinters in dead bark,twigs, fruit mummies, and cankers in the tree.Spores produced during the growing season arewashed onto the new fruit during rainy periods.Fruit infections occur primarily through woundsthroughout the season, but decay symptomsoften do not appear until fruit begin to mature.

SCOUTING: Record the number of fruits withwhite rot per 100 examined from each tree.This disease can be distinguished from black rotand bitter rot by the tan color and cylindricalpattern of the decay from the skin to the core,and by the red or purple surface halo.

L. APPLE DISEASE CONTROLSTRATEGIES AND THESIGNIFICANCE OF DISEASESCOUTING

To effectively control the major apple diseasesin Kentucky, growers must develop controlstrategies based upon a variety of factors. Theseinclude, the age, cultivars, general condition,and topography of the orchard; current andprojected weather conditions, knowledge of pasthistories of disease incidence, and presentdisease conditions as determined by scouting.

Cultural Control Strategies

Resistant cultivars. Where disease resistantapples fit the taste and preference of the

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gardener, they provide an economical way tocontrol diseases. Even cultivars that are partlyresistant, or at least not highly susceptible todiseases will be easier to manage. There aremany apple cultivars that are resistant to scab;many are also less susceptible to fire blight,cedar rust, and powdery mildew. Use thesecultivars if possible. Plant rootstocks thattolerate collar rot and fire blight diseases.

Sanitation. Disease-causing fungi and bacteriaoften survive from one year to the next ondiseased leaves, fruit, and branches. Reduce theactivity of the apple scab fungus by raking up orchopping fallen leaves into tiny pieces with apower mower in fall and winter. Remove anddestroy fruit "mummies" and cut out dead anddiseased twigs and branches during annual treepruning. Remove and destroy any abandonedand unsprayed apple or pear trees near theorchard.

Exclusion. Use only disease free nursery stockwhen planting a new block of trees. Try to usephysical barriers to block microbes from contactwith apples. The apple grower needs to beaware that some disease-causing microbes canbe kept out of the orchard, or can be kept fromspreading to a tree or block from one nearby.Soil contaminated with the collar rot fungusshould not be moved about, and pruning toolscontaminated with fire blight bacteria should bedisinfested before using in the next tree,especially during summer.

Environmental modification. Prune with theobjective of improving air and light penetrationinto the trees to reduce disease enhancinghumidity and moisture. Improve soil drainagewhere needed. You may want to considerconstructing canopies to keep leaves andflowers dry.

Eradication. Remove and destroy nearby cedartrees to break the cycle of cedar rusts on apple.Remove and destroy newly infected fruit spursusing MARYBLYT for timing.

Chemical Control

If cultural control strategies areeffeciently and completely applied, and if somelow level of disease can be tolerated, chemicalcontrols may not be necessary.

Although chemical control strategiesmay vary for each disease, they are generallyclassified as being protective, or reactive (wherethe control measure employed is in reaction tothe development of a problem), or acombination of the two. Protective strategies are based primarilyupon prior disease histories and the likelihoodthat a disease will show up year after year.Protective strategies are also used for diseasessuch as fire blight because of its erratic, yetpotentially devastating nature. With the morepredictable diseases such as apple scab, rust, andthe "summer diseases", as well as fire blight,control measures are generally in place prior toknown periods of infection. The primary role ofscouting in these instances is to provide insightinto where a control program can be adjusted toprovide for more effective disease control insubsequent seasons.

Scouting also allows reactive controlstrategies to be implemented into protectiveprograms. That is, scouting may detect lapses inthe effectiveness of the protective program dueto one reason or another. These lapses mayindicate ways to correct a problem before it getsout of hand. This is especially true of diseasessuch as apple scab and fire blight where thedevelopment of secondary inoculum, if leftunchecked, can soon result in poor diseasecontrol.

When properly implemented, aprotective spray program will effectively controlmost of the apple diseases encountered on ayearly basis. However, many of the chemicalsused in a protective program require that theybe present on the plant surfaces prior to thearrival of the disease organism. Unfortunately,this is not always possible because of theunpredictability of the weather in Kentucky.Many times it is simply impossible to apply

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spray materials prior to periods of infection.Fortunately, the development of a new breed offungicides, and a modified method of applicationprovide us with means to circumvent thisproblem.

Chemicals are now available which showsubstantial "kick back" action against certaindiseases. These chemicals have the ability tostop disease activity after infection has takenplace. This is very desirable in situations whereplant tissue is left unprotected during periods ofinfection, because of rapid growth and/orlengthened spray intervals. Sometimes they areincluded early in the season to assure the growerof eradicating infections that might have escapedprotectant fungicides. Consequently, thesechemicals add a certain degree of flexibility to aspray schedule and ease the demands of astrictly protective spray schedule. In most cases,growers having orchards with a history ofdiseases are best served with a strict protectivespray schedule.

In orchards where apple scab has beenkept under control, growers can reduce earlyseason fungicide use. Scab infections,determined using Mill's Table as explainedearlier, can be controlled using "eradicating" or"kick back" fungicides. Scab fungicide use canalso be reduced by using a four spray scheduleat tight-cluster, pink, petal- fall, and first cover.An eradicating fungicide such as myclobutanil(Nova), used in the four-spray schedule, willalso control cedar rust and powdery mildew.Beginning at first cover, traditional calendarsprays are then used.

Although the above discussion is verygeneral in nature, it should assist in thedevelopment of control strategies based uponindividual needs. It is also meant to tie togetherthe role of scouting in the development andimplementation of an effective spray schedule.For more specific information concerningdiseases and control recommendations forKentucky, please consult the current guide forcontrol of diseases and insects in home fruitplantings (ID-21). The Commercial Tree FruitSpray Guide (ID-92) or the Midwest Tree Fruit

Handbook (ID-93) are also useful additionalreferences.

More detailed information aboutsymptoms, causal organisms, disease cycle andepidemiology, and control can be found in theCompendium of Apple and Pear Diseases. Thisbook is available from The AmericanPhytopathological Society, 3340 Pilot KnobRoad, St. Paul, MN 55121.

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IV. INSECT MANAGEMENTA. CODLING MOTH

The codling moth larva is one of thevery destructive pests introduced from Europeby settlers. The larva of this insect is the "wormin the apple," and tunnels in the fruit to the core.This insect pest, left unmanaged, can cause nearcomplete loss of yield in some areas of thecountry.

Female moths lay the scale-like eggssingly on developing fruit or adjacent leaves orstems just after sundown each night. The eggsare very difficult to spot. Upon hatching thelarva enters into the calyx end or side of the fruitthen tunnel to the center where they feed anddevelop. Brown frass is often noticed near thecalyx end of the developing fruit. The larva ispinkish to white in color with a brown head andshield on the first segment behind the head.Larvae can reach 3/4 inch when full grown.Larval development is completed in 3 to 5weeks. Larvae pupate in a thick silken cocoonon the bark or other protected areas. The fullydeveloped larva is the overwintering stage.Pupation occurs in spring beginning at aboutbloom with adults first active in late April orearly May. In Kentucky, there are threegenerations each year. The adult is about 3/8inch, gray, with distinctive bronze areas on thebottom 1/3 of the wing.

There are a number of alternatives forcontrol of codling moth for the home owner.These alternatives include intensive monitoringof codling moth activity and development toaccurately time insecticide applications, baggingof the fruit to exclude codling moth, trapping ofmale moths to prevent mating, and banding ofthe scaffold limb to capture codling moth pupae.

PHEROMONE TRAPPINGPheromone trapping uses chemical lures

to attract male moths. These chemical lures aresynthetic copies of chemicals female mothsrelease and are used by males to locate females

for mating. A trap consists of plastic top andbottom held together by a wire hanger with thelure placed inside. The inner surface of thebottom is coated with a sticky material to holdthe insects once they land in the trap. Traps arehung in the southeast quadrant of the tree at eyelevel. It is important to distinguish codlingmoths from other moths captured in the traps.Codling moths can be recognized by the bronzeareas on the bottom 1/3 of the wings (SeeCommon Fruit Insects picture sheet, figure 1).

Traps should be put out at the pink stageof bud development. Every month, pheromonelures need to be replaced. Codling moths can bedistinguished from other insects in the traps bytheir bronze wing tips. For a list of the sourcesof various type of pheromone traps, see ENT-54, Vendors of Microbial and BotanicalInsecticides and Insect Monitoring Devices.

IPM MANAGEMENT OPTIONS

Pheromone Trapping & Degree DayAccumulation (intensive IPM)

Control of codling moth with intensiveIPM relies on the three tools; regularexamination of the trees and fruit (termedmonitoring), pheromone trapping to determinethe need for insecticides and accurately timetheir application, and the use of weatherrecording and degree day models. Trees shouldbe examined on a weekly basis for insects andmites beginning at the half-inch green stage inthe early spring and continued throughout thesummer. By mid summer, every other trip maybe omitted such that examinations are about twoweeks apart.

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Table 5. Predicting Codling Moth Development

DD Target Action taken when target reached

250 Egg hatch begins. An insecticide spray is recommended. If codling mothare abundant (more than 10 per trap per week), a second spray may benecessary 7 to 10 days later.

1000 When 1st generation moth begin to fly. Use their emergence as the nextbiofix.

1300 About when 2nd generation egg hatch begins. An insecticide spray isrecommended. If codling moth are abundant, a second spray may benecessary 7 to 10 days later.

Initial trap catches in the early spring aretermed biofixes. This information will be used topredict when egg hatch will occur andsynchronize insecticide sprays. In commercialIPM orchards, inclusion of an insecticide in thecover sprays is recommended as long aspheromone trap catches exceed an average offive moths per trap per week.

The biofix for the codling moth is thestarting date of the first sustained flight of malemoths captured in pheromone traps. Generally,this is when the fifth moth has been captured inthe trap. A few moths often emerge very early inthe spring ahead of the rest. Using the fifth mothas the biofix better represents when the majorityof the codling moths begin to emerge. Thisusually occurs just after petal fall. Codling mothtraps need to be examined daily in order toknow exactly when the biofix occurs. After thebiofix has occurred, degree days are calculatedon a daily basis and a running total is kept. Thecodling moth has a 50EF threshold temperature.These degree day accumulations are comparedwith the target values in the table above.

Codling moth trap catch records need tobe maintained throughout the summer tomonitor additional generations. However, afterthe initial biofix it is only necessary to examinethe traps twice a week. A threshold of fivemoths per trap per week is used to determine ifthere are sufficient levels of moths to warrant aninsecticide application. Imidan and Diazinon

provide good control of codling moth and areless toxic to beneficial insects and mites than themost of the other available materials. Bacillusthuringiensis can provide effective control ofcodling moth when applied at three to four dayintervals during egg hatch. Bacillusthuringiensis is available as an organicalternative.

Trunk Banding (Organic alternative)Another tactic that can be used by home

owners is the use of cardboard bands placedaround the trunk of the trees to serve aspupation sites for the wandering larvae. A fourto six inch band encircling the trunk or scaffoldlimbs will attract the larvae. Bands should be inplace before larvae begin to leave the apples insearch of pupation sites and removed anddestroyed before moth emergence begins. Thistechnique will not be effective if bands are notplaced on the tree and removed at the propertime. Bands should be placed on trees in Augustto capture overwintering pupae and removedand destroyed in December. Bands can also beused in the summer to capture pupae from thesummer generations, but timing is more difficult.If degree day records are kept, bands should beplaced on the tree about 450 degree days aftereggs are laid and removed 725 degree days afteregg lay. Trunk banding is usually more effectiveon smooth bark apple varieties that do not haveas many alternative pupation sites. Banding

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typically only controls a small proportion of thecodling moth as some drop to the ground or findother roughened areas in the bark to pupate.

SanitationThe value of good sanitation cannot be

over emphasized! Home owners shouldroutinely pick up and destroy fallen fruit,particularly during May and June. Fruit that areinfested with either codling moth or plumcurculio usually larvae drop prematurely withthe larvae still in them. This fruit should bepicked up daily and disposed of in such amanner that the larvae do not have a chance tocomplete their life cycle. This will help to reducedamage later in the season. Debris around thebase of the tree and loosened bark provideprotection for codling moth during the winterand during pupation. Debris should be removedduring the winter.

Bagging Fruit (Organic alternative)Bagging of the individual fruit has been

used experimentally with some success forcodling moth control in commercial apples inCalifornia. To control codling moths, bagsshould be placed around fruit at thinning (earlierif used for plum curculio control) to prevent egglaying. A 2-inch slit is made in the bottom of asmall brown paper bag. This opening is slippedover individual fruit and stapled shut to form agood seal. This is still experimental inKentucky, but worth investigating.

Mass Trapping of Male Moths (Organicalternative)

Home owners can use pheromone trapsto time insecticide sprays as discussed above, orto "trap out" all the male moths. This involvesusing enough pheromone traps such that all ofthe male moths in an area are captured in thetraps before the female moths mate. Femalemoths are then not able to lay fertilized eggs.Unfertilized eggs that are laid will not developand hatch. Typically, 2 to 4 traps per tree arerequired for this to be successful. Larger treesrequire more traps than smaller trees. This isless effective if there are additional sources of

mated females, such as other unmanaged trees inthe neighborhood or wild hosts for codlingmoths in nearby wooded areas.

Mating Disruption (Not advised forhomeowners)

This relies on saturating an area withenough of the female pheromone to confusemale moths such that they are not able to locatefemales. Unlike trapping of male moths, no trapsare involved, just pheromone dispensers. Themoths are not killed and the fruit have nochemical or physical protection. Typically a rateof 400 dispensers per acre is used. This methodis only effective where there are largecontinuous acreages (5 acres or more) of apples,and not recommended for small acreages or inurban areas where mated female moths mayimmigrate from surrounding areas. Matingdisruption is also being used for pests grapesand peaches commercially on in some regions.

B. PLUM CURCULIO

Plum curculio is a native pest of NorthAmerica that has caused considerable problemsin orchards throughout Kentucky. Like thecodling moth, this is a direct pest of apples asboth the larva and adult feed on the fruit. Whileit has only a single generation in Kentucky, itcan cause serious early season fruit damage toapple, pears, peaches and other stone fruitsoften resulting in 60% or greater losses inunmanaged trees.

The adult is a typical snout beetle, 1/4inch long, dark brown in color with patches ofwhite or gray (See Common Fruit insectsPicture sheet, figure 8). There are fourprominent humps on the wing covers. The snoutis 1/4 the length of the body, with mouth partslocated at the end. Plum curculio overwinters inthe adult stage in ground litter or soil usuallyoutside the orchard. Adults migrate into theorchards each spring. Often border rows nearwoods are the first to show injury.

The adult curculio becomes active in the

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early spring where it flies to trees and feeds onbuds, flowers and newly set fruit over a five tosix week period. This results in cat-facing of thefruit because of plum curculio feeding andegg-laying injuries. The female adult cuts a holein the fruit with her mouthparts and hollows outa small cavity then turns and deposits an egg inthe cavity. She then cuts a crescent-shaped siltwhich extends beneath the egg so as to leave theegg in a flap of flesh. Injury appears as a 1/8inch crescent-shaped cut on the fruit. Thisprevents the egg from being crushed by therapidly developing fruit. After about five days,the larvae hatch and burrow into the fruit. Thelarva is a leg-less grayish white grub with abrown head. Its length will be about 1/3 inchwhen full grown.

When the larvae are fully developed,they leave the fruit through clean-out holes. Nofrass or webbing will be evident. Frass isusually found around the calyx end on codlingmoth damaged fruit.

Surface feeding and egg-laying by theoverwintering adults can scar or misshape thefruit by harvest, while feeding by the larvaecauses premature drop of the fruit. In peaches,gummy material can often be seen at thelocation of the wound. These insects are activeprimarily at night and serious damage mayappear in orchards that have been scoutedrigorously even though the adults were notdetected. Currently there are no methods toaccurately predict when plum curculiodamage will occur.

Newly emerging adults in the latesummer will feed on apples for a short period oftime. They cause round, cylindrical feedingwounds in the side of the fruit that penetrateabout 1/4 inch often lead to localized rots on thefruits.

IPM MANAGEMENT OPTIONS

Petal-fall Control There is no effective method to monitor

for plum curculio adults or predict when and towhat extent damage may occur. Adult control is

accomplished by insecticide applications timedat petal-fall stage for apples. Serious plumcurculio damage is usually restricted to treesthat do not use this insecticide application.Developing fruit should be monitored carefullyfor the characteristic crescent-shaped plumcurculio laying scars. If these are seen on thefruit, a second insecticide application 10 to 14days after the first may be needed.

Sanitation Home gardeners can help reduce future

problems by picking up these damaged apples asthey fall off the tree and destroying them beforethe larvae emerge to go into the ground topupate. In apples, the larvae will only completedevelopment in fruit drops. Fruit need to pickedup daily and the fruit destroyed in such a mannerthat the larvae inside cannot completedevelopment. This will help to reduce additionaldamage later in the season.

Bagging Fruit (Organic alternative)Bagging of the individual fruit has been

used experimentally with some success forcodling moth control in commercial apples inCalifornia. To control plum curculio, bagsshould be placed around fruit after petal fall toprevent egg laying. A 2-inch slit is made in thebottom of a small brown paper bag. Thisopening is slipped over individual fruit andstapled shut to form a good seal. Bags can beremoved one month after petal fall. Bags shouldbe kept on the fruit for a longer period if usedfor codling moth control.Bags must be removed3-4 weeks before harvest to allow fruit to color.Bagging fruit on the tree is still experimental inKentucky, but worth investigating.

C. SAN JOSE SCALE

San Jose scale is an extremely importantindirect pest of apples, pears, peaches, andplums. It is a sucking inject that injects a toxininto the plant as it feeds causing localizeddiscolorations. The presence of reddish

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blemishes on fruit at harvest indicates potentiallydamaging numbers on the trees (See CommonTree Fruit Insect picture sheet, figure 6). Leftuncontrolled, San Jose scale can kill the entiretree in a couple years. If such damage is noted,inspect trees for scale, especially one year-oldwood. Purplish-red halos on young bark areindications of scale infestation. Often this verysmall insect goes unnoticed until largepopulations have developed.

San Jose Scale overwinter as immaturescales. In the spring, the tiny winged malesemerge and mate with the wingless females, andabout one month after the beginning of the maleflight, the first crawlers can be seen. Eggs arenot seen because females give birth to livecrawlers. These tiny yellow insects move aroundrandomly on bark and foliage before settlingdown permanently. A few days after settlingdown, crawlers will secrete a waxy coveringover their body that will protect them frompesticides. From this point on female scales willnot move. Males will remain in one locationuntil maturity, at which time the winged maleswill seek out females and the cycle will beginagain.

DETECTING CRAWLER MOVEMENTCrawler movement begins sometime

between mid-May and mid-June. Dark doublesided sticky tape should be used to monitor foremerging crawlers. A small amount of tape isapplied tightly to around a scaffold limb afterremoving surface debris with sandpaper. A limbwith a known infestation should be selected.Crawlers will appear as extremely smallflattened yellowish insects which can be seenwith a hand lens on the tape (especially aroundthe edges). Within two days, the crawlers willfind a permanent resting spot where they willfeed and begin to secrete a protective waxycovering. There are two generations each year.

IPM MANAGEMENT OPTIONS

Dormant Oil Effective control of San Jose Scale in

apples is obtained with a dormant oil spray to

control the overwintering nymphs. High volumeand thorough coverage is essential to gettinggood control with dormant oils. Trees should bepruned properly to allow for spray penetrationand good coverage. Typically an applicationmade during January is more effective againstscale than the delayed dormant applicationrecommended for European red mites and appleaphids. A mid-winter oil application isrecommended over a delayed dormantapplication in trees where scale has been aserious problem. Failure to use a dormant oilapplication may require additional inseasontreatments. These inseason treatments areusually more expensive and disrupt beneficialinsects that control secondary pests.

Pheromone Trapping & Degree DayAccumulation (intensive IPM)

Pheromone trapping involves the use ofchemical lures to attract male scales. Thesechemical lures are synthetic copies of thechemicals female scale use to attract the male for mating. A trap consists of a lure suspendedbetween the two sticky sides of a tent-like trap.Pheromone traps for this insect should be placedin scale infested trees either prior to or duringbloom. For a list of the sources of various typesof pheromone traps see ENT-54,

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Table 6. Predicting San Jose Scale Development

San Jose Scale DDtargets

Action taken when target reached

300 Place a piece of black tape, with sticky side out on an infested scaffoldlimb. Begin examining tape at least twice a week for minute scalecrawlers.

380-400 Crawler emergence should begin.

600-700 Maximum crawler movement. This is the best time for an insecticidespray.

Vendors of Microbial and Botanical Insecticidesand Insect Monitoring Devices. Lures need tobe replaced monthly.

Male scales are extremely small gnat-likeinsects, so traps need to examined carefully.Scales appear as a fine dust on the trap, usuallyconcentrated on the sticky surface near thepheromone lure. Trapping of scale is used toindicate when the activity of the male scalesbegins. The date that the first males are caughtin the trap is termed the biofix date. Male flightusually occurs after petal fall (mid to late April).Pheromone traps need to be examined daily inorder to know when biofix occurs. After thebiofix has occurred, degree days are calculatedon a daily basis and a running total kept. SanJose scale has a 51EF threshold temperature.These degree day accumulations are comparedwith the target values in the following table.

Insecticide applications for San Josescale control should be aimed at the immature,crawler, stage. Sprays directed against crawlersalso protect fruit from infestation. Sprays shouldbe timed about one week after the first crawlersare seen. If populations are heavy, a secondapplication two weeks after the first should beused. These applications aimed at the crawlershave little effect on the adult scales. BecauseSan Jose Scale occur on all parts of the tree,spray coverage as well as are very critical toeffective control. Although there is a secondgeneration later in the summer, crawlers emergeover an extended period of time making

insecticidal control of this generationimpractical.

Summer Horticultural Oil and InsecticidalSoap (Organic alternatives)

Monitor for San Jose scale crawlers andapply a 1 to 2% horticultural oil or 1 to 2%insecticidal soap application at peak crawlermovement. These have no residual activityagainst scale that may emerge after theapplication was made. An additional applicationmay be necessary to control scale if crawlers areemerging over a prolonged period. Horticulturaloils and insecticidal soaps provide alternatives totraditional synthetic insecticides and are lesstoxic to the applicator. Horticultural oil iseffective at controlling crawlers and settled firstinstar scale, while insecticidal soap can provideexcellent control of crawlers. While effectivecontrol can be obtained with a 1 to 2% summerhorticultural oil treatments, caution is advised asthese may be incompatible with some otherpesticides (particularly sulfur containingproducts), may be phytotoxic at highertemperatures (above 100EF and high humidity)and concentrations greater than 2%, and mayaffect fruit finish on some varieties.

D. EUROPEAN RED MITES

The European red mite is anotherintroduced pest in the US. It is a pest of nut,

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pome and stone fruits, and some berries. Thispest damages leaves and causes fruit russetting.European red mites can have 6 to 8 generationsper year, depending on the temperature.Summer generations may develop in as little as14 days.

The adult female mites are brick red withwhite spots at the base of six to eight hairs ontheir back. The male mite is more slender,lighter in color than the female, and has a morepointed abdomen. Overwintering eggs are red,globular and somewhat flattened (onion shaped)with a slender stalk on the upper side. Europeanred mites overwinters as eggs laid in roughenedbark around the bases of buds and spurs onsmall branches. During the summer eggs arespherical and laid on the underside of leaves.Egg hatch in the spring is closely correlated withbud development and begins close to the tightcluster stage. During the summer, eggs require7 to 14 days to hatch.

All active stages of the European redmite injure the foliage by feeding with piercingmouthparts and removing cell contents,including chlorophyll. Moderate to highnumbers of mites can cause the leaves to initiallyturn pale and with continued feeding the leavesturn bronze. Heavy mite feeding early in theseason can reduce tree growth, yield, and alsoeffect fruit bud formation for the following year.Some apple cultivars, such as 'Red Delicious'and 'Braeburn', are more prone to mite buildupand injury.

European red mites are rarely a problemon backyard apple trees. Predatory mites,ladybird beetles and the six-spotted thrips helpto maintain European red mite at nondamaginglevels. This mite is considered a secondary pest,it typically only builds to damaging levels afterits natural enemies have been depleted byinsecticide applications used to control codlingmoth or other pests. Minimizing insecticideusage and selecting insecticides that are leasttoxic to beneficial organisms will help tominimize problems with this mite.

IPM MANAGEMENT ALTERNATIVES

Dormant OilOverwintering mite eggs should be

controlled through the use of a delayed-dormantoil treatment, anytime between bud swell andhalf inch green. Control with dormant oilimproves the closer to egg hatch. High volumeand thorough spray coverage are necessary toprovide effective control of the eggs. Dormantoils are effective at controlling eggs of a numberof insect pests. Failure to use a properly timeddelayed dormant oil application may requireadditional inseason treatments. These inseasontreatments are usually more expensive anddisrupt beneficial insects that control secondarypests.

Monitoring and Economic ThresholdsTo monitor for mites, examine 5

hardened-off leaves from each of four scaffoldlimbs per tree. Certain varieties, such as RedDelicious, are more likely to develop largenumbers of mites. Using a hand lens, count allactive stages of pest and predatory mites.Predatory mites are more active and are tear-drop shaped. Determine the average number ofEuropean red mites per leaf. The economicthreshold for the mites varies with the time ofyear. Control is recommended early in the year(until April 1) if numbers of active mites exceedan average of 5 per leaf, during April and Maywhen mite numbers exceed 10 per leaf, or therest of the season if mite numbers exceed 15 perleaf. Vendex and Kelthane are general usemiticides for apples, but these are not availablein most areas. Diazinon will suppress mites butis not considered a miticide.

Summer Horticultural Oil Insecticidal Soap(Organic alternatives)

Management of mites during thegrowing season is based on monitoring,economic thresholds, and the use of summer oilor insecticidal soap treatments as needed. Oftenwhen heavy summer infestations exist, a secondtreatment may be required 10 to 14 days later.Horticultural oils provide an alternative totraditional synthetic miticides, are able to kill allmite life stages, and are less toxic to the

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applicator. While effective control can beobtained with a 1 to 2% summer horticulturaloil treatments, caution is advised as these maybe incompatible with some other pesticides(particularly sulfur containing products), arephytotoxic at higher temperatures (above 100EFand high humidity) and higher concentrations (>2%), and may affect fruit finish on somevarieties. Although less effective than summeroil treatments, insecticidal soap can providesome control of European red mites. Use theeconomic thresholds and repeat applications ifnecessary.

E. JAPANESE BEETLES

Japanese beetle was accidentlyintroduced into the United States in 1916. In theearly 60's, Japanese beetles spread intoKentucky from surrounding states. Japanesebeetles feed on the leaves of more than 300species of plants, including apple foliage anddamaged fruit. Kentucky provides a favorableclimate, abundant pasture areas for grubdevelopment, and few natural enemies of thebeetles. Fruit trees that may be severelydefoliated include apple, cherry, black cherry,peach, and plum.

The adult beetles feed on leaves of awide variety of trees and shrubs. Adults feed onthe upper surface of foliage, chewing out tissuebetween the veins, leaving a lace-like skeleton ofthe leaf. They usually feed in groups, starting atthe top of a plant and working downward. Thebeetles are most active on warm, sunny days,and prefer plants that are in direct sunlight. Asingle beetle does not eat much; it is groupfeeding by many beetles that results in severedamage. Trees that have been severely injuredappear to have been scorched by fire.

Adult Japanese beetles are 3/8-inch longmetallic green beetles with copper-brown wingcovers. A row of white tufts of hair project fromunder the wing covers on each side of the body.Japanese beetles overwinter underground in thegrub stage, and pupate near the soil surface in

the spring. Grubs spend 10 months in the soilwhere they feed on roots of grasses and can beserious pests. Adults emerge from the groundand begin feeding on various plants in June.Activity is most intense over a 4 to 6 weekperiod beginning in late June. By mid-July,numbers of beetles gradually diminish.Individual beetles live about 30 to 45 days.There is a single generation per year.

IPM MANAGEMENT OPTIONS

Monitoring and Insecticidal ControlLook for the presence of Japanese

beetles in the trees. Note the presence of liveJapanese beetles on the scouting form. Ifpresent, try to estimate the approximate numberof beetles per tree. There are few thresholdguidelines relative to when apples need to betreated for Japanese beetles. Carbaryl is themost effective insecticide used in managingJapanese beetles. However, because carbarylcan greatly increase problems with Europeanred mites, other insecticides arerecommended to manage low to moderateJapanese beetle populations in apples.Repeated insecticide applications may benecessary at 7-10 day intervals to preventreinfestation during the adult flight period, orafter heavy rains. Botanical insecticides such aspyrethrin provide an organic alternative tosynthetic insecticides for Japanese beetlecontrol.

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Japanese Beetle Traps (not advised)Many garden supply outlets have been

marketing Japanese beetle traps for a number ofyears. These traps are very effective at attractingand trapping large numbers of Japanese beetles.However, more beetles are usually attracted tothe trap than are actually captured. Researchconducted at UK has indicated that damage byJapanese beetles is usually more severe whenJapanese beetle traps are used. Placement oftraps at various distances and directions fromthe plants to be protected has not been shown tobe effective at reducing damage.

F. APPLE APHIDS

Generally four species of aphids - thegreen apple aphid, rosy apple aphid,apple-grain aphid and woolly apple aphid -attack apples in Kentucky. Three of theseaphids, the green apple aphid, rosy apple aphidand the apple-grain aphid are very similar inappearance. Damage is primarily on new foliageand fruit by feeding on plant sap using theirpiercing-sucking mouthparts.

Green apple aphid and apple-grainaphid are small pear to tear-drop shapedinsects. Color varies from light to dark green.Generally a pair of projections (cornicles) arepresent on the fifth or sixth segment.Mouthparts are piercing-sucking. Generallythese aphids are in colonies. The life cycle ofthese aphids begin with the egg, which is theoverwintering stage. Overwintering eggsgenerally are found on twigs, around buds or increvices in the bark. Eggs will generally beginhatching in early spring about green tip stage.The first generation of nymphs are all winglessfemales, called stem mothers. These femalesgive birth to live young, and a generation iscompleted about every fourteen days. In earlysummer some winged young are produced,these fly to new host plants and start newcolonies. During late summer and early fall, bothmale and female forms will be produced, mateand lay overwintering eggs. When first laid,

these eggs are green but soon turn shiny blackas they mature. Large number of aphids canstunt new growth and cause sooty mold todevelop on fruit and leaves.

The rosy apple aphid injects a toxinwith its saliva that causes the leaf to curl. Whileall apple varieties are attacked, 'Cortland', 'IdaRed', and 'Golden Delicious' are particularlysusceptible. Feeding on the leaves of fruitclusters often results in stunting andmalformation of the fruit. For this reason, rosyapple aphids are the most serious aphidsattacking apples. Honeydew produced by theaphids promotes the growth of sooty mold aswell. This becomes more noticeable as the fruitdevelops. Problems usually begin to appear afterpetal fall and by mid summer the aphids move toalternate hosts. The aphid overwinters on apple trees as eggslaid on twigs, bud axils, or in bark crevices. Theblack eggs are 1/2 mm long and football shaped.Shortly after silver tip the eggs hatch. Thenymphs color changes from dark green to purpleas they grow (See Common Fruit Insects picturesheet, figure 5). The aphids continue toreproduce on apple until summer, then wingedforms are produced which migrate to otherhosts such as dock and narrow-leaved plantain. Apple growers should monitor their treescarefully for rosy apple aphids, a few coloniescan rapidly infest the entire tree. Because theseinfestations will curl the leaves, early control isimportant. Once the leaves are tightly curled,adequate spray coverage and control is moredifficult. There are a number of predators thatoften control rosy apple aphid, so distortedleaves should be open to determine if the aphidsor predators are still present before makingcontrol decisions.

The woolly apple aphid differs fromother apple aphids in appearance, life cycle, andthe type of damage inflicted. A colony appearsas a cottony mass generally clustered in woundsand pruning scars on the trunk and branches ofthe tree. The aphids themselves are purplish incolor surrounded by white, cottony, thread-likesecretions. Egg-laying wounds by the periodicalcicada are ideal sites for infestation.

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The life cycle of woolly apple aphid isvery complex. The winter may be passed in twoforms, the egg or immature nymph. Nymphshibernate underground on roots of apple.Wherever apples and elms are close together,overwintering eggs are be deposited in cracks orprotected places on the elm. During spring, eggswill hatch into wingless nymphs which feed onelm buds and leaves. In early June, a wingedform is produced which migrates to apple andother hosts. These individuals feed on wounds inthe branches and trunk, and as the number ofaphids on the above ground portion of the treeincrease, many work their way down to theroots and trunk below ground surface. It is thefeeding on the roots that produces the greatestdamage. Young trees are often injured the mostby this pest. Rootstocks vary in susceptibility towoolly apple aphid and susceptible rootstockswill form galls around the infestation sites. UseM111 or M106 if woolly apple aphid is aserious problem. Control of these aphids is verydifficult when they attack the roots.

During the summer, repeated woollyapple aphids generations of wingless individualsare produced. In the fall, winged individuals areproduced which fly back to elm and layoverwintering eggs, while some wingless formsmay remain on both above and below groundparts of apple throughout the winter.

IPM MANAGEMENT OPTIONS

Delayed Dormant OilThe green apple aphid, apple-grain aphid

and rosy apple aphid overwinter as eggs ontwigs and bark crevices of apple trees. A delateddormant oil application between green-tip andhalf-inch green controls newly hatched aphids.Failure to use a properly timed delayed dormantoil application may require additional inseasontreatments. These inseason treatments areusually more expensive and disrupt beneficialinsects that control secondary pests.

Monitoring and Economic ThresholdsExamine four leaf terminals on each of 5

scaffold limbs on each tree for active aphid

colonies. When monitoring for woolly appleaphid, examine four pruning scars on each of 5scaffold limbs per tree. Record the total numberof aphid infestations per 20 leaf terminals, fruitclusters or pruning scars by species. Carefullyexamine woolly apple aphid colonies todetermine if live aphids are present. Predatorscan completely destroy the colony but the waxyresidue will remain. If a leaf terminal has ANYlive aphids on any of the leaves, it is consideredinfested. Treatments are recommended when5% of the terminals are found to have rosy appleaphid infestations. Other aphids such as thegreen apple aphid and the apple grain aphid donot curl leaves and have higher actionthresholds. Treatments are not recommendedfor these aphids until 50% of the terminals areinfested. Treatments for woolly apple aphid arerecommended when 50% of the pruning scarsare infested with live colonies. Diazinon ormalathion can provide effective control of thesepests.

Insecticidal Soap and Summer HorticulturalOil (Organic alternatives)

A 1 to 2 % application of insecticidalsoap or summer horticultural oil can provideeffective control of these aphids. Use themonitoring and economic thresholds and applythese as necessary. Neither of these will provideany residual control, so thorough coverage isessential. Control of rosy apple aphid after theleaves have curled may be difficult. Whileeffective control can be obtained with a 1 to 2%summer horticultural oil treatments, caution isadvised as these may be incompatible with someother pesticides (particularly sulfur containingproducts), are phytotoxic at higher temperatures(above 100EF and high humidity) and at highconcentrations (> 2%), and may affect fruitfinish on some varieties.

G. LEAFROLLERS

There are several different species ofLepidoptera commonly known as leafrollers.

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The most common of these insects are theFruit-Tree leafroller, Oblique-Bandedleafroller, Omnivorous leafroller and theRed-Banded leafroller. Leafrollers commonlyweb leaves together forming small pockets inwhich they can feed on leaf tissue inside whilebeing protected from predators. Occasionallywhere leaves touch fruit, or two fruit aretouching, leafrollers will feed on the surface ofthe fruit.

The Fruit-Tree leafroller is a nativepest occurring in the northern half of the UnitedStates. The adult is a brown moth slightly largerthan the codling moth. Thin light markings willappear in various patterns across the frontwings. The larva is a slender worm, pale greenin color. The head is black and a black spot willappear just behind the head. The larva mayreach 3/4 inch in length.

The insect overwinters in the egg stage.Hatching will occur about the time buds beginto open. Larvae feed on buds, blooms, leavesand fruits. In June full grown larva transforminto pupae, inside folded or rolled up leaves.Moths appear in about two weeks, lay theireggs, and die. Only one generation occurs eachyear.

The Oblique-banded leafroller issomewhat less important than the Fruit-treeleafroller. Adults are brown with three darkbands on the front wings. Wingspread is aboutone inch. Larva are small and green with blackheads.

Overwintering occurs as partially grownlarva inside tightly woven cases, on the hosttrees. During spring, larva emerge and continuefeeding until late May. Pupation occurs andadults will emerge in June. One or twogenerations may occur. Damage is done byyoung larva mining the leaves, with larger larvafeeding inside rolled up leaves.

The Red-banded leafroller is generallya problem north of the Ohio and east of theMississippi Rivers. However, they are at timesa problem in Kentucky. Adults are brown, aboutthe size of the codling moth, and have broadreddish bands on each forewing. Larva are

green, slender and will reach a length of about2/3 inch (See Common Fruit Insects picturesheet, figure 3).

Winter is passed in the pupal stage. Thispupa will generally be found in a silken cocoon,in detritus at the base of host trees. Mothsemerge in the early spring, and lay their eggs inclusters on the bark of host trees. The firstgeneration larva will emerge and begin feedingat about petal-fall. Up to four generations mayoccur each season.

IPM MANAGEMENT OPTIONS

Monitoring and Economic Thresholds(Organic)

Leafroller populations are by regular treeexaminations. Examine 10 leaves on each of fivescaffold limbs per tree. Look carefully for leafmining injury and folded leaves. Record thenumber of live leafroller larvae per 50 leaves.An average of 2 larvae per 50 leaves justifiescontrol. Sprays containing Bacillusthuringiensis provide excellent control ofleafrollers.

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H. INSECT CALANDER- = Pest may be present at low levels.X = Pest frequently found a economically damaging levels during these periods.

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SPRAY MIXTURECONSIDERATIONS:

T None of these multipurpose mixturescontrols all of the insects and diseases youare likely to encounter. Not realizing this,many users tend to apply mixtures morefrequently and at higher rates trying, in vain,to control some pests.

T Multipurpose mixtures lack flexibility sothat when only a fungicide is required (e.g.during bloom), an insecticide also is appliedeven though it is not needed and could bedamaging.

T Most multipurpose mixtures are moreexpensive than those you prepare.

T Mixtures containing dicofol miticide maycause a problem because their continued usemay lead to the development of dicofol

V. PESTICIDE USE & SAFETYUsing Pesticides

Pesticides should only be used as a lastresort to kill insects and disease pathogens.While many home fruit growers may opt to usepesticides, there are several safety issues thatneed to be addressed before using them. Handlethese chemicals carefully to prevent injury toyourself, other people or pets. Although thepesticides suggested for home use are the leasthazardous available, certain precautions are stillnecessary. For more information on usingpesticides, spray equipment for home fruitgrowers, how to spray fruit trees, harvestrestrictions, storage of pesticides, and noteson specific pesticides, see ID-21 in theappendix of this manual.

Multi-Purpose or All-Purpose Fruit Sprays

Insecticides and fungicides are oftenneeded at the same time on a plant to protect itagainst attack by both insects and diseases.There are all-purpose fruit sprays on the marketwhich contain a mixture of insecticides andfungicides that give adequate control for mostcommon problems and are easy to use. If amixture containing Sevin is used, apply this onlythree to four weeks after petal fall on apples andpears. Sevin thins or causes fruit to drop ifapplied before this date. Sevin may also causebuildup of pest mites.

These commercially prepared mixturesare convenient to use and reduce the number ofpesticides the homeowner must store safely.

You can mix the all-purpose fruit spraywith additional pesticides, but there are somelimitations with which you should becomefamiliar. If you are in doubt about spraycombination injury, check the label. Apply themixture to a small portion of the tree and waitto see what happens. Spray burn should showup in 24 to 48 hours. If burn results, do notapply the combination. If you plan to mix yourown combination, it is advisable to use wettable

powders to reduce the problem of plant injury.

Where To Purchase Pesticides

Most garden centers or stores with yardand garden departments where pesticides aresold have the commonly recommendedpesticides. Many agricultural supply or farmerco-op centers also carry them. Some pesticidesare difficult to obtain in some parts of the stateand can be ordered through the mail.