rowing apricots cherries , p eaches & p lums in w · opportunity for success. when choosing a...

T E R Y L R . R O P E R , D A N I E L L . M A H R , PA T R I C I A S . M C M A N U S

GROWING APRICOTS,CHERRIES, PEACHES,& PLUMS IN WISCONSIN

A3639

Prunus cerasus

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The stone fruit plant . . . . . . . . . . . . . . . . . . . . . 2

Site selection and preparation . . . . . . . . . . . . . . 4

Selecting plant material . . . . . . . . . . . . . . . . . . . 4

Planting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

Fertilization . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

Weed management . . . . . . . . . . . . . . . . . . . . . . . 7

Training and pruning . . . . . . . . . . . . . . . . . . . . 8

Spring frost protection . . . . . . . . . . . . . . . . . . . 12

Fruit thinning . . . . . . . . . . . . . . . . . . . . . . . . . 12

Harvest . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

Storage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

Insect pests . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

Diseases . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

Problem solving . . . . . . . . . . . . . . . . . . . . . . . . 26

Glossary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29

Related publications . . . . . . . . . . . . . . back cover

CONTENTS

Apricot, cherry, peach,& plum trees produce some of the most delectable fruitavailable. They can also be pleasing additions to your home

landscape. But before planting any of these fruit trees—collectivelycalled stone fruits—you should consider whether you have the time, space,and expertise to grow them successfully. To be successful, stone fruitsshould be planted only in the very best sites and raised with care.

Apricots,Cherries,Peaches &PlumsI N W I S C O N S I N

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Most stone fruit trees are very sensitive to winterinjury. This results in short tree life and crops lostto spring frosts. Fruit buds of peaches, nectarines,and Japanese plums usually die if temperaturesfall to 0°F. Lower temperatures will damage orkill the trees. Sweet cherries are slightly morehardy. European and native plums, tart cherries,and apricots have hardier fruit buds and woodthan peaches or Japanese plums, but they maystill be injured by severely cold winters, even infavorable sites.

Only tart cherries and European plums should beconsidered for commercial plantings in Wisconsin.Apricots, sweet cherries, peaches, and Japaneseplums are not sufficiently winter hardy for com-mercial production. There is very little market forsand cherries and other exotic stone fruits.

This bulletin outlines the basics of stone fruit pro-duction for amateurs or hobbyists. For moreinformation, contact your county Extension office.

THE STONE FRUIT PLANTAll of the stone fruits belong to the genus Prunus.This genus is characterized by fruit with a hardinner seed—the pit—covered by a fleshy outerlayer. The name “stone fruit” comes from thishard seed, or stone. Table 1 shows other charac-teristics of common stone fruits.

People have also produced hybrids such as plum-cots, a combination of plum and apricot. Cherryplums will grow well in Wisconsin, but plumcotsare not hardy here.

All stone fruits produce flowers and bear fruit onthe sides of branches (laterally). Terminal buds—those at the ends of branches—always becomeleaves, not flowers or fruit. Stone fruit flowerstend to open from the outside lower portions ofthe tree and progress to the inside and top of thetree. Flowers may bloom on the sides of shortshoots called spurs, which are found on woodthat is 2 years old or older, or at the base of1-year-old wood. Cultivars that bear fruit onspurs are more desirable because they are moreproductive than those that bear fruit on 1-year-old wood.

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Some stone fruits are self-fruitful. That is, pollenproduced by the flowers of one tree will fertilizeeach other successfully. Plants that are self-fruit-ful can be planted singly. Cross-fruitful treesrequire a second cultivar planted nearby, usuallywithin 100 yards. Even some self-fruitful stonefruits will bear heavier crops if a second, compat-ible cultivar is planted alongside.

Stone fruit trees purchased from nurseries consistof two parts: the scion, which is the abovegroundportion of the tree that produces fruit, and therootstock, which is below ground and providessupport to the tree while absorbing water andnutrients (figure 1). Nurseries graft these twoparts to produce the stone fruit trees you maybuy. Both parts of the tree are important andshould be considered before purchasing trees.Not all stone fruit rootstocks are hardy inWisconsin. Suggested rootstocks for each speciesare outlined in Extension publication Rootstocksfor Fruit Trees in Wisconsin (A3561).

The trunk and branches of stone fruit trees pro-vide structural support for the crops of fruit andmay be manipulated to grow in a number ofways. Limbs with wide crotch angles relative tothe trunk are stronger than those with narrow

Scion(desired cultivar)

Rootstock

Bud union

Scaffoldbranches

TABLE 1. Characteristics of common stone fruits grown in Wisconsin. All belong to the genus Prunus.

Common name Species Fruit size Pollination Space

Apricot P. armeniaca medium to small self1 125 sq. ft.

Tart cherry P. cerasus small self 100 sq. ft.

Sweet cherry P. avium small cross1 150 sq. ft.

Peach and nectarine2 P. persica large self 125 sq. ft.

Sand cherry P. besseyi very small cross 40 sq. ft.

Nanking cherry P. tomentosa small cross 40 sq. ft.

Plums P. domestica medium self1 125 sq. ft.1 Some exceptions exist to the pollination requirements indicated. Your nursery can provide more information about specific

cultivars.2 Nectarines are peaches that have been bred not to produce fuzz.

FIGURE 1. Important parts of a young stone fruit tree. Thebud union shows where the rootstock and the scion werejoined by grafting.


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crotch angles. Limbs should not branch off fromthe trunk at the same height, because this is detri-mental to the trees.

Through photosynthesis, leaves produce carbo-hydrates that provide for both fruit growth andthe growth of the tree. Leaves that grow in theshade cannot produce sufficient carbohydrates.Trees should be trained so that branches do notshade each other and receive sun for at leastthree-fourths of the day.

SITE SELECTION ANDPREPARATIONOnce a fruit tree is planted, it’s not easy to moveit to a better location. So, you should plant in awell-prepared, suitable site. Begin site selectionand soil preparation the season before planting.Planning ahead allows time to adjust the soil pH,control perennial weeds, and improve the soil.

The ideal site for stone fruit trees is a gentleslope, where cold air can settle into adjacentlower areas. The bottoms of valleys are “frostpockets” and may be several degrees colder thannearby hillsides. Hilltops are also undesirable, asthey may be very windy and exposed.

Stone fruit trees will grow best in fertile, sandyloam soils, though they will grow in all but therockiest or heaviest clay soils. The soil must havegood internal drainage, as fruit trees will notgrow with “wet feet.” The soil should be neutralto slightly acidic, with a pH of 6 to 7.

Since fruit trees require full sun at least three-fourths of the day, shady locations are not suitable.

Site selection also means making sure you havesufficient space for your trees. Table 1 shows theapproximate area various stone fruit trees willoccupy, ranging from 40 to 150 square feet. Somestone fruit trees can become quite large, so makesure to allow plenty of room for each tree.

Once you select a suitable site, begin soil prepa-ration. Control perennial weeds either byrepeated tillage or by using non-residual herbi-cides. Herbicides containing glyphosate, such asRoundup or Kleenup, are well-suited to peren-

nial weed control. But be careful not to spraythese herbicides on desired plants, becauseglyphosate will kill any plant it contacts.

You should also take a soil test of the site to adepth of 6 inches. Follow the soil test recommen-dations to adjust soil pH: add lime if the soil istoo acidic, or add sulfur if the soil is too alkaline.To improve soil tilth, aeration and water-holdingcapacity, add organic matter such as manure,leaves, or compost. For information on how tosample soil and where to send samples for test-ing, see Extension publication Sampling Lawn andGarden Soils for Soil Testing (A2166).

SELECTING PLANT MATERIALStone fruits are less hardy than apples and pears.You must choose cultivars carefully to have anyopportunity for success. When choosing a culti-var, consider the intended use (fresh eating, jamor jelly, canning, freezing), flavor, and color.Remember, the cultivar must be winter hardy inyour area. Peaches and sweet cherries should beplanted only in southern Wisconsin, and even thenyou should choose only the hardiest cultivars.

You’ll need to know whether the cultivar you’reconsidering is self-fruitful or requires a secondcultivar nearby. Table 1 lists the pollinationrequirements of different stone fruits. For cross-pollinated fruits, you should be sure that the twocultivars flower at the same time so they can pro-vide pollen to one another. In addition, somesweet cherries are cross-incompatible, whichmeans that successful pollination may require athird cultivar. Your nursery should be able toadvise you in selecting cultivars. Pollinizer treesshould be planted within 100 yards of each otherfor effective cross-pollination.

Don’t let nostalgia for old cultivars influenceyour choice. New cultivars frequently have betterflavor, texture, hardiness, and store longer thanold cultivars. More information on cultivars well-suited to Wisconsin can be found in Extensionpublications Home Fruit Cultivars for SouthernWisconsin (A2582) and Home Fruit Cultivars forNorthern Wisconsin (A2488).

Peaches are not generally recommended forWisconsin. However, in extreme southeasternWisconsin thousands of home gardens havepeach trees that bear fruit. The peach cultivarsmost likely to succeed are Reliance, HarrowBeauty, and Madison, all of which are self-fruit-ful. Apricot cultivars include Goldcot and Harcot.Sweet cherries that may survive in Wisconsininclude Gold, Hedelfingen, Lapins, and Van.Lapins is self-fruitful; the others require cross-pollination.

Rootstock selectionStone fruit trees available at commercial nurseriesare typically grafted or budded to combine adesirable scion to a rootstock with desirable char-acteristics. Nurseries do not propagate stonefruits from seed since the offspring will not beidentical to the tree that produced the seed.

Rootstocks are very important to fruit trees,because they control tree size and may be moreor less winter hardy than the scion.Unfortunately, at the time of this writing thereare no reliable dwarfing rootstocks for stonefruits that are winter hardy in Wisconsin. A dis-cussion of rootstocks for common stone fruits isfound in Extension publication Rootstocks for FruitTrees in Wisconsin (A3561).

Procuring plant materialIt is best to purchase stone fruit trees directlyfrom a reputable nursery or garden center. Goodnurseries will sell only trees that are free ofknown viral diseases and true to the cultivar’s

name. Some advanced hobbyists and commercialgrowers propagate their own trees, but this isrisky. While propagating procedures for stonefruits are straightforward, the operations takeskill and practice. The typical success rate foramateurs is less than 25%. Further, good nurs-eries discard weak plants which amateurs mighttry to save.

PLANTINGStone fruit trees must be planted correctly forbest results. Transplant trees in the spring, afterseverely cold weather has passed and the soil hasdried and warmed. Fall planting of bare root fruittrees is not recommended in Wisconsin.

Potted fruit trees may be planted any time of theyear if given proper care. The procedure forplanting bare root and potted trees is similar.

Bare root. If trees arrive from the nurserybefore they can be planted in your area, keepthem in a cool place but don’t allow them tofreeze. Open the container and make sure theroots are still moist. If not, add a small amount ofwater to moisten the roots, but don’t saturatethem. You may soak the tree roots in a bucket ofwater for 2 to 4 hours before planting to moistenthe roots.

Potted. Potted trees may be kept for 2 to 3weeks in the container. Potted trees need regularwatering, but don’t overwater them. The soilshould dry slightly between waterings. Removethe tree from the pot before planting and spreadthe roots. If the roots circle the inside of the con-tainer, make several vertical cuts through theroots and spread them away from the trunk.

When you are ready to plant the tree, dig a holelarge enough to accommodate the roots withoutcutting or bending them. If one root is very long,it can be shortened, but in general don’t prunethe roots. The hole should be deep enough so theentire root system will be in the ground. Don’tadd fertilizer or fresh manure to the hole. Fill thehole with soil and gently pack it in with yourfoot to ensure good contact with the roots. Water

Stone fruit plant Rootstock

Apricot Manchurian apricotseedling

Cherry (sweet or tart) Mahaleb seedling

Plums Myrobalan seedling

Peach and nectarine Siberian C or Baileyseedling

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the tree immediately. Most stone fruit trees willbe grafted from seedling rootstocks, and the graftunion of these trees should be planted at orslightly above the final soil surface.

Young trees should be staked at planting.Suitable staking materials include 3⁄4-inch metalelectrical conduit, pressure-treated 2 x 2 lumberor 2- or 3-inch-round wood stakes. Drive thestake into the ground 3 to 4 inches from the treeand use tape (masking, PVC, electrical) or fabricstrips to securely fasten the tree to the stake. Donot use wire, rope, or other materials that willnot allow the tree to expand as it grows. You willneed to periodically inspect the tape or other fas-tening materials for wear.

IrrigationYoung trees benefit from regular watering.During the first year, a stone fruit tree shouldreceive 1 to 2 inches (3 to 5 gallons) of waterweekly. If rain is insufficient, you must providewater. As trees get older their roots explore alarger volume of soil, and irrigation becomes lesscritical. Don’t wait for trees to wilt or show othersigns of water shortage before watering. On theother hand, overwatering can be equally detri-mental. Overwatering fills air spaces in the soiland keeps oxygen from reaching the roots. Wetsoils also have a greater potential for root rots.Measured watering throughout the season, fromplanting to leaf fall, will be most beneficial. Don’tignore the trees once the fruit have been har-vested. Sufficient water is still important.

Pruning at plantingNewly planted trees may need to be pruned. Theexact pruning to be done depends on the shapeyou desire for the tree. Prune unbranched “whip”trees to 30 to 40 inches tall. Pruning encouragesstrong lateral branches to form just below the cut.You control the height of the lowest branches bythe height of your cut. These branches will formthe basic framework of the tree. More informa-tion on pruning is provided in the “Training andPruning” section.

FERTILIZATIONLike all plants, stone fruit trees require someessential minerals in order to grow. Have yoursoil tested the year before planting fruit trees andincorporate all recommended nutrients into thesoil. Micronutrients such as zinc, copper, andboron are not required in great amounts, and fer-tilizing with these nutrients is usually not neededin Wisconsin.

You can apply nutrients as granules, liquids, ormanures. Granular fertilizer is usually the leastexpensive form and is easy to apply. Incorporategranules into the soil by tilling or wateringwithin 24 hours after application. Liquids can beapplied with a hose-end applicator or wateringcan. Dilute liquid fertilizers according to packagedirections. Manures are typically low in mineralcontent and should be aged before shallowlyincorporating them. Extension publicationOrganic Soil Conditioners (A2305) offers moreinformation about organic fertilizers.

FIGURE 2. An unbranched “whip” tree atplanting. Remove the top of the tree 30 to 40inches above the final soil line. Branches willarise just below the cut.

30–40 inches

A few weeks after planting you can make a lightapplication of a fertilizer containing nitrogen.Apply the fertilizer evenly within the drip line ofthe tree (the ground area under the tree’scanopy). The rule of thumb is to apply 1 ounce ofactual nitrogen to each tree per year of tree age,but not to exceed 1⁄2 pound of actual nitrogen pertree annually. Be sure to include any fertilizerapplied to lawns under trees in your total annualamount.

To calculate the amount of fertilizer to apply,divide the nitrogen needed, according to thisrule, by the percentage of nitrogen in the fertil-izer. For example, a 3-year-old tree should receive3 ounces of actual nitrogen. To calculate howmuch ammonium sulfate (which is 21% nitrogen)to apply, divide 3 ounces by 0.21 for a total appli-cation of 14 ounces of fertilizer.

You may need to adjust the standard nitrogenapplication to the tree’s actual growth. Shoots onyoung stone fruit trees typically grow 15 to 20inches each year, while shoots on bearing treesgrow 8 to 12 inches annually. If growth is lessthan normal, apply 25% more fertilizer. If growthis more than normal, don’t apply any nitrogenfor a year.

WEED MANAGEMENTManagement of the soil around the trunk of thetree affects tree performance. Don’t allow grass orother vegetation to grow within 18 inches of thetrunk. A vegetation-free zone of 2 to 3 feet is evenbetter. Grass and other vegetation compete withtrees for water and nutrients. Grass growing upto tree trunks also makes it difficult to mow with-out damaging the trunk. Mower injury frequentlykills home fruit trees.

Prevent weed and grass growth around treetrunks by cultivating, mulching, or applying her-bicides. Cultivate shallowly (no deeper than 1 to2 inches) to avoid damaging tree roots. Organicand inorganic mulches are ideal because theyprevent weed growth and conserve soil moisture.Apply 3 to 4 inches of an organic mulch such asshredded bark, bark chips, or wood chips. Spreadthe mulch in a donut fashion around tree trunks

(figure 3). Avoid heaping mulch around treetrunks. This can lead to fungal rots on the trunkor attract rodents that gnaw on the bark and maygirdle the tree.

Herbicides containing glyphosate, such asRoundup or Kleenup, are the easiest to use to killweeds growing around tree trunks. For youngtrees, wrap the trunk with aluminum foil or plas-tic wrap before applying herbicide. Applyglyphosate according to label directions andavoid getting spray on the trunk or leaves (oryou!). Be careful not to get glyphosate on vegeta-tion other than the weeds you want to remove,because it will kill whatever vegetation it touches.Spray herbicides only when winds are calm.

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FIGURE 3. To keep weeds away from trees,pile organic mulch around the base and mold it ina donut shape. Don’t heap mulch against the trunkbecause this can contribute to fungal rots orattract rodents.

Mulch

TRAINING AND PRUNINGAnnual training and pruning is essential for pro-ducing large yields of high-quality stone fruits.Training and pruning should be aimed at accom-plishing these goals:

■ Light management. All limbs of the treeshould receive light. The tree should not shadeitself.

■ Size containment. Don’t allow trees tobecome larger than their allotted space, nortoo large to prune or harvest.

■ Renewal of fruiting wood. Apricots andpeaches produce fruit only on 1-year-oldwood and must be pruned to encourage newgrowth to provide fruiting wood. Once theybegin fruiting, make a few large cuts each yearto encourage development of fruiting woodfor next season.

Stone fruit trees are pruned the same at plantingand are treated generally the same the first year.After the first year you’ll need to select one ofthree training systems: open center, centralleader, or modified leader. Each system isdescribed on the following pages.

Regardless of the training system, each year youshould remove any dead or broken branches,suckers, water sprouts, and branches formingnarrow angles with the trunk that cannot bespread. Remove the weakest of crossing orclosely parallel branches. Remove downward-growing branches. Thin out dense areas, particu-larly in the top of the tree. Thinning cuts (remov-ing an entire branch to its point of origin) arebetter than heading cuts (removing a portion of abranch) for making trees less dense. Keep theheight of tall trees manageable by cutting tallbranches in the tops of the trees back to a weaklateral branch.

Use tools specifically made for pruning, such ashand shears or long-handled loppers. Keep themsharp and clean. Don’t use hedge shears—man-ual or electric—because they make jagged cuts.Do not leave stubs when pruning. Make cutsclose to the trunk, but do not remove the branchcollar (figure 4). These cuts will heal mostquickly. Do not use pruning-wound paints orcoatings, as they keep the wound moist, allowinginsects and diseases to invade the tree. It is bestto allow the wood to dry naturally. The tree willproduce growth that covers the cut.

The best time to do major pruning is while thetrees are still dormant in spring (March andApril). Dense canopies can be thinned again inlate summer (late July and early August), butdon’t prune after mid-August as this can delaydormancy and predispose trees to winter injury.

FIGURE 4. Prune branches close to the trunk,as along line a–b. Be careful not to cut too closeto the branch collar, as along line c–d, and do notmake stub cuts, like line a–e. Pruning along linea–b allows the cut to heal most quickly.


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d

a

be

c

Open centerThis system will produce vase- or bowl-shapedtrees with good light distribution in the canopy,but its structure may be weaker than that of cen-tral leader or modified leader trees. Peach treesare usually trained to an open center form.

First year spring. During the first year ofgrowth, lateral branches should be encouraged todevelop strong, wide crotches. Do this byspreading the branches with clothespins ortoothpicks when they are no more than 6 incheslong (figure 5). In the first dormant season afterplanting, cut the central leader out of the tree justabove the uppermost scaffold limbs.

Second year spring. Remove about 25% of theextension growth from branches by cutting justabove a strong, outward-facing bud to encouragefurther branching.

Third year spring. Remove any branchesgrowing vigorously into the center of the tree.Also remove any weak, downward growingbranches. Unless few lateral branches have beenformed, don’t cut the tips off branches. Continuewith maintenance pruning to prevent shading, tokeep the canopy open, and to maintain tree size.

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FIGURE 5. Use clothespins or toothpicks to spreadbranches that are no longer than 6 inches. Wedge tooth-picks between the trunk and branches. Attach spring-type clothespins to the trunk and position them againstbranches.

First year spring Second year spring Third year spring

O PEN CENTER

Central leaderThe central leader system calls for training a treeto grow with a Christmas tree shape (conically).The tree has one major vertical trunk with threeor four tiers of lateral scaffold branches. Theupper limbs should always be shorter than thelower limbs so the tree does not shade itself. Youcan easily train sweet cherries to a central leader.

First year spring. Select four to six lateralbranches to be the lowest tier of scaffolds. Theseshould have wide crotch angles and should beevenly spaced around the trunk. Prune out the

remaining branches. If the lateral limbs have notbranched, you may wish to remove 25% of theirlength to induce branching.

Second year spring. By this time the centralleader should be tall enough to have a second tierof scaffolds. If branches have grown starting 25 to30 inches above the top scaffold of the lower tier,leave them. If not, cut the leader 25 to 30 inchesabove the top scaffold. This will induce branch-ing for the second tier of scaffolds.

Third year spring. When the central leader hasgrown 25 to 30 inches beyond the second tier,repeat the procedure for the third tier.


10First year spring Second year spring Third year spring

C ENTRAL LEADER

11First year spring Third year spring

Modified leaderThe modified leader is a hybrid of the open cen-ter and the central leader system. The advantageof this system is that there is more fruiting woodso the tree should produce better than an opencenter tree. Apricots, plums, and tart cherries arefrequently trained to a modified leader system.

First year spring. Select four to six lateralbranches to form the lower tier of scaffolds. Lookfor branches that have wide crotch angles and areevenly spaced around the trunk. Prune out theremaining branches.

Second year spring. To produce the secondtier of scaffolds, select four to six more branchesbeginning about 20 inches above the lower tier.Once the second tier is in place, remove the cen-tral leader.

Third year spring. Remove weak branches andany branches that grow inward, downward, orthat cross.

P runing old, overgrown trees to restore produc-

tion of high-quality fruit is difficult if not impossible.

Neglected trees will never produce as much high-

quality fruit as new trees.

To lower the height of a tall tree, remove one or two

of the tallest limbs. Make the cut where the limb joins

the trunk. Such heavy pruning cuts will stimulate the

tree to produce more vegetative growth, especially

near the cuts. Spread heavy pruning over 2 to 3

years. The interior of dense canopies may need to

be thinned out in order to allow light throughout the

tree canopy.

RECLAIMING AN OVERGROWN TREE

M ODIFIED LEADER

Second year spring

Training bush cherriesNanking cherries and sand cherries are usuallytrained as bushes rather than as trees. Newshoots arise annually from the roots. These needto be thinned out every year to retain productiv-ity. Shoots older than 5 years are less productiveand should be removed to allow room foryounger, more productive shoots. Cut old stemsas close to the ground as possible. Thin out thetotal number of stems and branches in thecanopy so that light is well-distributed and nobranches are continually shaded.

SPRING FROST PROTECTIONThe potential for spring frost injury can be lim-ited by planting stone fruit trees in only the bestsites (see “Site Selection”) and by planting late-flowering cultivars. However, in Wisconsin latespring frosts are common, and stone fruit trees—apricots in particular—bloom early.

In addition to plant and site selection, two othertechniques can be used to protect flowers orimmature fruit from late frosts. Covering treeswith tarps of some sort will hold heat in the treecanopy. The tarp must be in place before the tem-perature falls below 34°F and must remain inplace until temperatures are above freezing thefollowing morning. Secure the tarp to the tree orthe ground to prevent it from blowing off duringthe night. You may provide additional heat byplacing a lighted, 60- to 100-watt light bulb insidethe tree canopy. The idea is to provide more heatto keep the temperature under the tarp and withinthe tree canopy above 30°F. The tarp must beremoved the next day before heat builds up insidethe canopy. Keeping the canopy warmer duringthe day may hasten fruit development and makethe fruit even more susceptible to later frosts.

Low-volume sprinkling can also be used for frostprotection but is not recommended for home gar-deners. Protection depends on keeping a continu-ous film of unfrozen water on the tree branchesand flower buds for the entire night. As the waterfreezes into ice, it releases heat and keeps thetemperature at or above 30°F. Sprinkling mustcontinue until the air temperature is above freez-ing. This method will protect flower buds toabout 20°F if there is little or no wind.

FRUIT THINNINGDuring years with favorable weather, stone fruittrees may produce, or “set,” large quantities offruit. This will result in many small fruit at har-vest. To avoid this situation, thin the crop byremoving some of the immature fruit. To improvethe size of the remaining fruit, thin as early as


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After

Before

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possible after the fruit set and before they aredime-sized. The fruit of peach, plum, and apricottrees should be spaced at least 6 to 8 inches aparton a branch. Remove the smallest fruit and leavethe larger ones. Large fruit early in the seasonwill be large fruit at harvest. Thinning will resultin fewer fruit of higher quality. Cherries andcherry plums are usually not thinned.

HARVESTOne advantage of home-grown fruit is that it canbe picked at peak ripeness, when it is both sweetand juicy. Fruit picked for commercial harvestmust be harvested after it is mature, but before itis completely ripe to withstand handling andshipping.

Different stone fruits ripen over a long periodranging from early July through September. Youshould harvest fruit when they are fully mature,but before they begin to fall from the trees. Asfruit mature, they become softer and their fleshbecomes sweeter and more juicy. The skinchanges from a bright green color to a softergreen, then to yellow, and finally to orange, yel-low, purple or red. Usually the best way to deter-mine if stone fruits are ripe is to taste the fruit.

All the stone fruits except sweet cherries are usu-ally harvested without stems. Try to harvest thefruit by gripping it in the palm of your handrather than with your fingers. This is not possiblewith small fruit. Twist the fruit slightly whilepulling. Avoid pulling spurs or branches fromthe tree—these structures contain fruit buds fornext year’s crop. Sweet cherries should be pickedwith the stems if you plan to store the fruit foreven a few days. If you plan to eat or processsweet cherries soon, you may pick them withoutstems. Gently place the fruit into your pickingcontainer. Never throw or drop fruit. If you musttransfer fruit from one container to another, do socarefully to avoid bruising.

You may need to protect fruit from birds thatgather when the fruit begin to mature. Birds willpeck holes in the fruit or eat the entire fruit,depending on alternate food sources and thenumber of birds. You can deter birds from eatingalmost-ripe fruit using netting or scare devices.

Netting is the most effective means of protectingfruit from birds. Bird nets are available frommany sources, and satisfactory nylon netting canbe purchased at fabric stores. To be effective, theentire tree canopy must be covered and the net-ting secured around the trunks. If the bottom ofthe net is left open, birds can still get in. It is, ofcourse, difficult to net large trees, but this is stillthe best way to protect fruit.

You can deter birds, at least temporarily, withscaring devices. Aluminum pie tins hung fromouter tree branches will protect trees for a fewdays. Mylar tape hung in trees can also be effec-tive. Scare balloons have worked in some situa-tions. Propane-powered cannons and electronicdevices that emit bird distress sounds are effectivefor a time, too, until birds become acclimated tothe sound. These noisemaking devices are notrecommended in residential areas—no matter howunderstanding your neighbors are. Rotate meth-ods during a season and delay using any scaretactic as long as possible for maximum effect.

STORAGEStone fruits are highly perishable and will onlystore for short periods of time, usually a fewdays to 2 weeks. Fruit will keep longer if it ispicked slightly before its peak of ripeness and ifit is cooled to 32° to 40°F as soon as possible.Store only sound fruit. Sort through the fruit anddiscard any that are blemished, diseased,bruised, or punctured. These will not keep well.Store fruit in perforated plastic bags to maintainhigh humidity levels. Table 2 shows storagetimes for stone fruits under optimal conditions.

INSECT PESTSMany types of insects attack the foliage, fruit, orwood of stone fruit trees in Wisconsin. Not all ofthese occur at damaging levels every year oreven everywhere they occur.

There are two approaches to insect managementon stone fruits: a preventive approach whereinsecticides are applied routinely regardless ofactual insect damage, and a curative approachwhere controls are applied only when pests arepresent and capable of causing significant damage.

The preventive approach is often used by grow-ers who are unable to do routine pest monitoringor who are uncomfortable trying to identify pestsand damage. A minimal preventive program usesone to three insecticide sprays per year, timed atpetal fall, 2 to 3 weeks after the first spray, and2 to 4 weeks before harvest. This spray programusually protects a substantial proportion of fruit.Where the best possible fruit quality is desired, orwhere insect numbers are high, a more thoroughinsecticide program may be necessary, withapplications at 10- to 14-day intervals starting atpetal fall and extending to harvest.

The curative approach is the best way to manageinsect pests. It requires learning to recognizecommon pests and the types of injuries theycause, monitoring pest activity weekly through-out the growing season, and applying insecti-

cides only when necessary. This approach allowsthe buildup of beneficial insects that naturallyhelp to control many orchard pests.

Table 3 will help you determine when to monitorfor the most serious insect pests. It summarizeswhen insects are likely to be present, and the besttimes to apply controls. Use the chart togetherwith the detailed insect information below todecide when controls are appropriate.

Several methods can be used to monitor insectactivity, including sticky traps, pheromone traps,and visual inspection. Not all methods work onall insects. We offer specific suggestions for moni-toring each pest listed below.

Pheromone traps are sticky traps with a synthe-sized attractant that mimics the natural odor orpheromone produced by female moths forattracting males for mating. The traps catchmales and help identify the period when matingand egg-laying occurs. Traps can be purchased atbetter garden centers and through mail-order cat-alogs. For best results, follow the manufacturer’sdirections.

Do not use insecticides during bloom. Stonefruits are pollinated by honey bees and otherinsects. Broad-spectrum insecticides applied dur-ing flowering will kill these beneficial insects andinterfere with pollination.

The following descriptions are of the most seri-ous stone fruit insects in Wisconsin. The insectsare grouped by whether they primarily damagethe fruit or the plant. More thorough and inclu-sive descriptions and color illustrations of insectsand their damage can be found in Extension pub-lication Common Tree Fruit Pests (NCR063). Foradditional information on specific pests and pes-ticides, see also the list of publications at the endof this book.


14

TABLE 2. Stone fruit storage duration underoptimum conditions, at temperatures of 32° to 40°F.

Fruit Duration

Cherriessweet 1–2 weekstart, sand, bush, and nanking 3–5 days

Apricots 1–2 weeks

Peaches 2–3 weeks

Plums 3–5 weeks,depending on type

Fruit-damaging insects

Cherry fruit flies Hang monitoring traps in mid-June.Damage can continue until harvest.

Apple maggot Hang sticky traps last week in June.Control is most critical July through August.

Caterpillars

Fruittree leafroller Hang pheromone traps early June. Criticalmonitoring time during bloom. Spray once atpetal fall.

Redbanded leafroller Hang pheromone traps mid-April and mid-July.Spray once at petal fall and for second genera-tion if necessary.

Green fruitworm Spray once before blossom or at petal fall.

Japanese beetles Apply sprays as needed or use floating rowcovers as soon as adults appear.

Plum curculio Apply first spray at petal fall. Check fruit foregg-laying damage in spring, feeding damage inlate summer.

Plant-damaging insectsAphids Can occur throughout growing season. Not

usually damaging on established trees.

Caterpillars Several species can damage fruit and foliagethroughout season. Apply controls as necessary.

Scale insects Monitor fruit, foliage, and stems throughoutyear. Spray before budbreak or during crawlerstage.

Spider mites Most damage occurs mid-June through August.Apply dormant spray, treat as needed through-out season.

Wood borers Hang traps according to flight periods of thespecific pests as indicated in text. Apply insecti-cides during adult flight.

Mar

chApr

ilM

ay

June

July

Augus

tSe

ptem

ber

Octobe

rCom

men

ts

TABLE 3. Approximate dates for monitoring and controlling insect pests. Dates will vary depending on weatherand location in state. Do not apply insecticides during blossom period.

Monitor adult insects Monitor larvae and/or damage Control periods

15


16

Fruit-damaging insectsThe most serious insect pests of stone fruits arethose that directly damage the fruit. Theseinclude cherry fruit flies, apple maggot, caterpil-lars such as leafrollers and fruitworms, and plumcurculio.

Apple maggot

The apple maggot is a typeof fly closely related to thecherry fruit flies. The larvaetunnel throughout the fruit,causing it to deteriorate. Asthe name implies, the apple

maggot is primarily a pest of apples. If uncon-trolled, it is the most serious insect pest of applesin Wisconsin. It is also a summer pest of plumand apricot from July until harvest. Nativehawthorns are also hosts.

Type of damage. The adult apple maggot flylays eggs under the skin of fruit. It may lay sev-eral eggs in a single fruit. The fruit decomposesaround the site of this sting, causing a small,darkened depression. Tiny, transparent larvaehatch from the eggs and tunnel through the fruit,leaving slender, brown trails. Infested fruit startto deteriorate and eventually fall from the tree.

Description. The apple maggot fly is abouttwo-thirds the size of a common house fly. Itsbody and wings are marked with black andwhite bands and spots. The larvae are headless,legless, cream-colored maggots about 1⁄3-inchlong when fully grown. Young larvae are verytiny and virtually transparent, making them diffi-cult to find within fruit, even with a microscope.

Monitoring. Hang sticky traps during the lastweek in June and continue trapping until harvest.There are two types of apple maggot traps: yel-low sticky boards and red sticky spheres. Yellowtraps are less efficient but pick up insects beforethey start to lay eggs. The red sphere trap is effi-cient for monitoring reproductively mature flies.An “apple volatile” lure, available for hangingwith the red sphere, greatly increases the attrac-

tiveness of this type of trap. Apple maggot trapsare not as selective as pheromone traps; theycatch many different types of insects. For this rea-son, it is important to be able to distinguish theapple maggot fly from other, similar insects. Thetwo types of cherry fruit flies discussed earlierare easily mistaken for the apple maggot fly. Youcan identify them based on differences in wingpattern (see illustration). For management pur-poses, keep in mind that the cherry fruit fliesattack only cherry, while apple maggot damagesplum and apricot as well as apple and pear.

Prevention and control. Use, destroy, or buryinfested fruit as soon as they fall from the tree.Do not compost these fruit because the larvaemay survive.

Apple maggots can be controlled by trapping.Use the round red spheres along with the com-mercial apple volatile bait. Research shows thatone trap per 100 fruit will catch most flies andwill minimize fruit injury. In larger plantings,ring the planting with traps by hanging themevery 50 feet along the edges of the orchard.

Apple maggots can be controlled with insecti-cides. In lightly infested areas, spray in early Julyand repeat once or twice at 2- to 3-week intervals.Reduce the time between sprays in heavilyinfested areas. Sprays can be timed by usingtraps to monitor for adult fly activity; spraywhen the first flies are caught, and again aftersubsequent catches, but no more frequently thanevery 2 weeks.

Wing-banding pattern of fruit flies.

Cherry fruit fly

Black cherryfruit fly

Apple maggot

Caterpillars—leafrollers, fruitworms,and others

The larvae (caterpillars or “worms”) of severaltypes of moths feed on stone fruit foliage andfruit. Leafrollers (especially redbanded leafroller,obliquebanded leafroller, and fruittree leafroller)and green fruitworms are the most common, butothers include inchworms and cankerworms.Most of these are early-season pests, causingdamage shortly after bloom; a few cause damagein midsummer.

Type of damage. The larvae feed on bothleaves and fruit. Young larvae feed on leaves dur-ing the blossom period, causing minimal damageto the tree. Leafrollers use silken webbing to rollleaves or tie two or more leaves together, creatinga refuge where they live and feed. Leaves areoften tied around clusters of young developingfruit, and the leafroller larvae feed on the fruitsurface, causing superficial smooth or corkybrown scars. Such damage caused early in fruitdevelopment may heal naturally. Although thefruit is scarred, the flesh will remain usable andwon’t rot. In contrast, green fruitworms do nottie leaves together, and they feed deeper, inyoung fruit only. Feeding damage from greenfruitworms may cause the fruit to drop from thetree. More mature fruit in summer are not able toheal the fruitworms’ feeding wounds, and theyusually fall from the tree and rot. Leafrollers,green fruitworms, and similar caterpillars do nottunnel into fruit, but feed only from the surface.

These caterpillars feed on many types ofbroadleaf trees and shrubs, often in wooded areasadjacent to where orchards are planted. Mosttypes also feed readily on other cultivated fruitplants, including apple, pear, and even berries.

Description. Leafroller larvae are pale yellow topale brown and have a yellowish, brown, orblack head, depending on the species. They growfrom 1⁄8 inch long at hatching to about 3⁄4 inchlong. Green fruitworms are much larger androbust, growing to over 1 inch long. They aregreen and may have small white spots or palelines which run the length of the body. The adultsof these insects are moths.

Monitoring. Check during the blossom periodfor signs of larval feeding, which may appear astattered leaves or leaves with holes chewed inthem. Also check for leaves that appear stucktogether; carefully separate these to look forleafroller larvae. Pheromone traps are availablefor redbanded, obliquebanded, and fruittreeleafrollers. Traps will help determine flight peri-ods and therefore when eggs are being laid.

Prevention and control. Insect populationsvary from year to year, depending in part ontheir numbers in nearby forests, wood lots, orabandoned fruit trees. In some years they may beessentially nonexistent, whereas in other years,noticeable defoliation or fruit injury may occur ifthe trees are not protected. Insecticide spraysapplied at petal fall (the very end of bloom, when75% of the flowers have fallen) will control mosttypes of caterpillars. Traditional insecticides maybe used. Also, microbial insecticides containingthe active ingredient Bacillus thuringiensis willusually provide satisfactory control as long asthey are applied when the larvae are very young.

Cherry fruit flies

Two closely related species of fruit fly attacksweet and tart cherries, but no other stone fruits.In addition to cultivated cherry, they also com-monly infest wild cherries. Black cherry fruit flyand cherry fruit fly have similar life cycles andcause the same type of damage, and thus will bediscussed together.

17

1⁄2–3⁄4"


18

Type of damage. The adult fly punctures thefruit and lays its eggs within. After the eggshatch, the larvae (maggots) tunnel through thefruit. The fruit may appear normal for severaldays, but eventually sunken areas develop.Usually only one maggot infests each fruit. Ifsubstantial infestation occurs near harvest, thedamage may not be apparent externally. If thecherries are used for preserves, the small mag-gots may be a noticeable contaminant. Feedinginjury not only damages the fruit directly, butalso allows brown rot and other fruit diseases todevelop. Eventually, the fruit will be completelyunusable.

Description. Adult cherry fruit flies are abouttwo-thirds the size of a common house fly. Blackand white bands and spots mark the body andwings. The larvae are headless, legless, cream-colored maggots, about 1⁄3-inch long when fullygrown. Young larvae are very tiny and virtuallytransparent, making them difficult to find withinfruit, even with the aid of a microscope.

Monitoring. Cherry fruit flies are best monitoredusing yellow sticky traps. Black cherry fruit flycan begin flight as early as mid-June and willcontinue through mid-July, with peak flight inlate June. Peak flight for cherry fruit fly is early tomid-July, with some continuing flight into earlyAugust. Therefore, traps should be hung in mid-June. Continue trapping until the end of harvest.Trapping efficiency can be improved by adding aspoonful of ammonium hydroxide to the traps.Place the liquid in a small jar or vial and hang itimmediately under the trap. Some commercialtraps already include another attractant calledprotein hydrolysate; if you use these traps, theammonia bait is unnecessary.

Check the traps at least twice weekly. There isabout a 1-week period between the time fliesemerge and when their eggs are developed andready to lay. Therefore, if you use an insecticide,the first application should be made about 5 to7 days after the first fly is trapped.

Prevention and control. If possible, eliminatewild hosts such as choke cherry growing imme-diately adjacent to the orchard. However, cherryfruit flies are strong fliers and can move consider-able distances.

In small plantings, baited monitoring traps canbe used to suppress cherry fruit flies, but severaltraps need to be hung in each tree. Trapping isnot highly efficient and some fruit injury can beexpected, especially in areas where populationsare high.

Cherry fruit flies can be controlled with insecti-cides. In lightly infested areas, spray them inmid-June and repeat once or twice at 2- to 3-weekintervals. Reduce the time between sprays inheavily infested areas. If using monitoring traps,time the first spray 5 to 7 days after the firstcatch, and then no more frequently than every10 days. Cherry fruit flies can continue egg layingthrough the harvest period. If populations arehigh, it may be necessary to use an insecticidewith a preharvest interval of 1 to 5 days—checkthe insecticide label for this information.

Japanese beetle

The Japanese beetle is a relativelyrecent invader of Wisconsin. It ismost serious in the southern partof the state, but extends into cen-tral Wisconsin, and will likely con-tinue to be an increasing problem. Populationscan build to very large numbers, resulting in sub-stantial damage to fruit and foliage.

Type of damage. They feed on many types oftrees and shrubs. The USDA lists stone fruitsamong the beetle’s top 10 favorite food plants.Unlike other fruit crops, Japanese beetles preferto feed on fruit of stone fruits. The beetles clusteron the fruit and cause substantial injury, espe-cially within the 2- to 3-week period just beforepicking.

19

Description. The 1⁄3 inch beetles are reddishbrown and metallic green, with a series of whitetufts of hair around the edge of the wing covers.The larvae are white grubs that feed on plantroots and organic matter in the soil, especiallyunder turfgrass.

Monitoring. Japanese beetles are strong fliersand can invade from considerable distances fromoutside the immediate garden area. Watch forthem from late June through early August.Modest defoliation (10–15%) will not affectmature fruit trees or yield, but higher levels ofdamage will stress trees and reduce crop yieldand quality. Substantial defoliation to young treeswill delay their establishment.

Prevention and control. Many insecticidesregistered for use on stone fruits will killJapanese beetle adults, but others may soon fly infrom adjacent untreated areas. Japanese beetletraps are available and can catch thousands ofbeetles, but, because they can attract more beetlesthan they catch, research has shown that the useof traps can actually increase damage to smallgardens. If you use traps, they should be placedat least 50 feet away from plants you wish to pro-tect. If you have just a few small fruit trees, youmay find success using the woven fabric “float-ing row covers” that are available to protect gar-den plants from flying insects.

Plum curculio

Plum curculio is a native species of weevil—a type of beetle. As its name suggests, its pre-ferred host is plum, but it attacks other stonefruits as well as apple and pear. Plum curculio iscommon throughout Wisconsin and is one of themost damaging pests of stone fruits.

Type of damage. Plum curculios damage fruitin three ways: egg laying, feeding by larvaewithin the fruit, and feeding by adults at the fruitsurface. The adult female scars the fruit surface ategg laying by cutting small crescent-shaped flapsin the skin of young fruit. This damage occurswhen the fruit are smaller than 11⁄2 inches indiameter. As the fruit grows, it becomes verymisshapen, with lumps and dimples. Larvae tun-

nel through the fruit, causing considerable deteri-oration and, eventually, fruit drop. Adults feedon the fruit surface, causing small, shallow irreg-ular holes. The surrounding areas decay and rot.

Description. Adult weevils are less than 1⁄4 inchlong and are gray-brown to dark brown. Theplum curculio has three pairs of bumps on theback, and a long, curved snout on the front of thehead. The larvae are pale and grublike, with adistinct, pale-brown head but no legs. Fullygrown larvae are about 1⁄4 inch long.

Monitoring. Monitor for adult weevils frommid-April through mid-June and again from lateJuly through mid-September. To monitor, spreada white sheet beneath a tree, then sharply tap thebranches with a padded stick. Adults will fall tothe sheet and pretend to be dead. Check fruit for4 weeks beginning shortly after petal fall; lookfor the characteristic crescent-shaped scars.

Prevention and control. Collect and burywindfalls as soon as they fall. Since the weevilscan easily tunnel through soil, bury infested fruitat least 2 to 3 feet deep. If possible, remove vege-tation from fence rows and eliminate other siteswhere beetles may overwinter. Chickens readilyfeed on migrating beetles and may reduce theirpopulations some. Do not allow chickens to for-age in areas treated with pesticides or wherethere may be pesticide drift or runoff.Appropriate insecticides applied at petal fall and10 to 14 days later will provide good control.

1⁄4"

egg-laying scars causedby plum curculio


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Plant-damaging insectsFeeding by insects and mites on foliage orbranches can hurt host trees various ways. Thedamage weakens trees so that they grow poorly;it reduces bloom and fruit set; and it results inthe production of small, low quality fruit. Theplant-damaging insects and mites includeaphids, caterpillars, scale insects, spider mites,and wood borers.

Aphids

Several types of aphids feed on thefoliage and young stems of stonefruits throughout the growing sea-son. Those most commonly foundon stone fruits include the blackcherry aphid (on cherries), greenpeach aphid (on all stone fruits), andapple grain aphid (on plums). Applegrain aphids may heavily infest buds and veryyoung growth in spring, but they cause no injuryand do not require treatment.

Type of damage. Aphids often cause newlydeveloping leaves to twist and curl. They feed bysucking plant sap from leaves and small succu-lent stems. During feeding, they inject saliva intothe plant to aid in feeding and digestion. Aphidsaliva is often toxic to the plant, resulting instunted, twisted, or curled leaves.

Description. Aphids are usually less than 1⁄8inch long and are generally found in largecolonies, often on the undersides of the leaves.They vary in color from pale yellow to lightgreen to pale rose to dark purple. Occasionally,winged individuals can be seen in the colony;these may differ in color from the winglessforms.

Monitoring. Check leaves throughout the grow-ing season. Infested leaves will be curled, withthe aphids feeding on the lower leaf surfaces.Clusters of small aphids are easy to see.

Prevention and control. Native natural ene-mies, such as lady beetles and lacewings, helpcontrol all aphids that attack stone fruit trees.

Lacewing eggs can be purchased commerciallyand released into the trees during bloom to aug-ment local natural enemies; we do not recom-mend purchasing lady beetles because they dis-perse too rapidly after release.

An appropriate insecticide, applied at petal fall,will control aphids. Insecticidal soap will providegood control if coverage is thorough. Again,moderate aphid activity will not hurt establishedtrees and usually does not warrant the use ofbroad-spectrum insecticides.

Caterpillars

Various caterpillar species are important defolia-tors of fruit trees. Some feed on fruit as well asleaves. Eastern tent caterpillar and fall webwormare common problems. Both caterpillars are rela-tively large and hairy. Eastern tent caterpillarsspin densely webbed “tents” in early spring,soon after the first leaves have formed. The lar-vae first feed in groups, outside of their tents andreturn to their tents when not feeding. Severalcolonies can completely defoliate a tree. Fall web-worms produce large, loose tents that surroundthe colonies of feeding larvae. There are two gen-erations: spring and late summer. For a discus-sion of control, see the previous section on cater-pillars in “Fruit-Damaging Insects.”

Scale insects

Scales are tiny insects that feed by sucking sapfrom branches, leaves, or fruit. During most oftheir lives, scale insects are motionless and cov-ered by a hard, waxy coating. The shape and sizeof the coating varies with species. The San Josescale and oystershell scale occasionally infestWisconsin stone fruit trees. Both types can alsoinfest apple trees.

Type of damage. Newborn scales, calledcrawlers, can settle on fruit. Their feeding leavessmall, red halos (1⁄8 to 1⁄4 inch in diameter) ongreen or yellow fruit. These marks appear moredistinct as the fruit mature. In addition to injur-ing fruit, heavy infestations can stress trees andkill stems and branches.

1⁄8"

21

Description. San Jose scale is very tiny, onlyabout 1⁄16 inch when fully grown. Its covering iscircular and looks from the side like a broad, flat-tened cone. It overwinters as a partially grownscale on the tree; females mature and producecrawlers by mid-June. Crawlers seek appropriateplaces to settle and start to feed. A second gener-ation occurs in summer. Because of their tiny sizeand brown color, San Jose scales are difficult tosee on branches or trunk, and they are usuallynoticed first when they start to infest fruit. Bythis time, the tree is usually infested heavily.

Oystershell scale is less common than San Josescale but causes similar damage. It is slightlylarger and elongated in the shape of a musselshell. It overwinters in the egg stage under thescale covering of the mother. Eggs hatch 1 to 3weeks after blossom and crawlers move aboutuntil they find an appropriate place to settle onthe stems or branches of the tree; occasionallythey will settle on young fruit. The scales growslowly throughout the year, and there is only asingle generation per year.

Monitoring. Because of their small size, scaleinsects are often overlooked unless they areabundant. If you notice the characteristic haloeson fruit, carefully examine the tree trunk andbranches for scale colonies.

Prevention and control. Lime sulfur sprays orsuperior oil applied during dormancy controlsboth types of scale. Crawlers can be controlledwith one to two applications of a conventionalinsecticide, timed 2 to 4 weeks after petal fall.

Spider mites

Spider mites are very tiny creaturesthat are more closely related to scorpi-ons, spiders, and ticks than they are toinsects. There are many different typesof spider mites, all of which are plantfeeders. Two types, European red miteand twospotted spider mite, com-monly attack the leaves of stone fruits.European red mite is most common on plum, butalso occurs on other stone fruits. Twospotted spi-der mite can be found on all stone fruits. Bothalso occur on apples, where they tend to be bothmore common and more damaging than on stonefruits.

Type of damage. Mites suck sap and nutrientsfrom leaves. Their feeding damages leaf surfaces,causes moisture loss, and reduces the plant’scapacity to grow and produce fruit. Damagedleaves first become slightly yellow, then take on apurplish or bronze coloration.

Description. Both species of spider mite arevery tiny—only about 1⁄50 inch long when fullygrown. Twospotted spider mites are pale yellow,with a large dark spot on either side of the body.These mites produce very fine silken webbingalong the leaf edges and veins, which becomesquite noticeable where their population is dense.European red mites are a dark, reddish brown,and they do not produce silken webbing. Bothtypes of mites have many generations each yearand can build to very high levels. They repro-duce more rapidly in warm, dry weather and canaverage more than 100 per leaf.

Monitoring. Because of their very small size, itis helpful to have a 10- or 15-power magnifyingglass when checking for mites. If you see leaf dis-coloration and suspect mites, check 10 randomlyselected leaves from each tree. Most mites will beon the lower leaf surfaces. When smashedbetween thumb and forefinger, or against a pieceof white paper, the mites will leave a smallbrownish stain. In early spring, check stems nearbuds for eggs of European red mites. If eggs arepresent, a dormant spray will control them.

1⁄ 8"1⁄16"San Jose scale Oystershell scale

Size of aperiod. 1⁄ 50"


22

Prevention and control. Spider mites rarelydamage trees in home orchards except wherebroad-spectrum insecticides are frequently used.

Natural controls are important for regulating spi-der mites. Heavy rains wash many from leaves,especially on smaller or well-pruned trees. Manybeneficial predators also occur naturally. Theseinclude tiny predatory mites as well as lady bee-tles, lacewings, and other insects that feed onmites. These beneficials are more prevalent whentrees are not heavily sprayed with broad-spec-trum insecticides.

A dormant superior oil spray applied at the timeof “tight cluster” (as the flower buds first becomenoticeable) will kill overwintering eggs ofEuropean red mite. However, this treatment isineffective against twospotted spider mites,which do not overwinter on the tree. Insecticidalsoap and certain types of conventional insecti-cides will suppress mites during the growing sea-son, but may not provide complete control. Ifnumbers are high, two applications 5 to 7 daysapart may be needed. Commercial orchardistshave access to specific miticides that provideeffective control.

Wood borers

Several types of wood borers can seriously dam-age and even kill stone fruit trees. The mostimportant of these are peachtree borer, lesserpeachtree borer, and American plum borer. Theadults of all of these insects are moths. Thepeachtree borer lays eggs from late June throughmid-August. The lesser peachtree borer lays eggsfrom early June through early September. TheAmerican plum borer has two generations peryear, laying eggs from mid-May to mid-June, andagain from mid-July through the end of August.

Type of damage. Eggs of all three species aremost commonly laid near wounded areas of thebark on the trunk or major branches. Injuries sus-ceptible to infestation include sun scald, frostcracks, lawn mower injury, injury from mechani-cal cherry shakers, and previous borer sites.Wood borers lay eggs on the surface of the barkor in bark cracks; the young larvae tunnel into

the tree as soon as the eggs hatch. They tunnelthrough the cambium layer right under the bark.The damage girdles the tree. When the infesta-tion is in a branch, only that branch will showsymptoms. If the injury is to the trunk, the entiretree will suffer. Symptoms include poor growth,small, sparse, and off-color foliage, and poorbloom and fruit set. If left untreated, the infestedareas will continue to be reinfested over severalyears, and the tree will eventually die.

Description. The adult moths of peachtreeborer and lesser peachtree borer have clear, scale-less wings. They are slender moths, peachtreeborer being about 3⁄4 inch long and lesserpeachtree borer about 1⁄ 2 inch long. The generalbody color of both is a dark blue-black. Peachtreeborer females have a distinct, orange band acrossthe midpoint of the abdomen. The larvae of boththese species are cream colored; the head is paleto dark brown. Peachtree borer larvae attain alength of about 11⁄ 2 inches whereas those of lesserpeachtree borer grow to about 1 inch.

The adult American plum borer is a moth about1⁄2 inch long. The wings are covered with scales.The front wings have a pale gray-brown back-ground color, with a broad, dark, irregular banda little more than halfway from the wing base.The larvae grow to about 1 inch. The larval colorcan vary from dirty white to grayish purple todark red. The head can also vary in color frompale to dark brown.

Monitoring. All three insects can be monitoredwith pheromone traps. Also, look for signs ofnecrotic or loose bark that may have oozing sap,or holes with sawdust-like material. When suchareas are found, use a sharp knife and carefullycut away the bark to determine if larvae or theirgalleries (tunnels) can be found.

Prevention and control. Prevent injury to thetrunk and branches of trees, so that wood borersdon’t lay eggs there. You can clean up isolatedinfestations by carefully cutting away theinfested tissue, being certain to remove all larvae.You can then paint these areas with asphalt-based tree wound compounds, which will retardreinfestation. Insecticides directed with a hand-

23

held spray wand at the trunk and lower branchesshould be timed when the insects are flying andlaying eggs. This will require the use ofpheromone traps and also proper diagnosis ofthe type of borer present.

DISEASESMany disease-causing pathogens (fungi, bacteria,viruses, and nematodes) attack stone fruit trees.Diseases may damage the fruit directly, making itunattractive or inedible, or they may weakentrees by injuring or invading the leaves, trunkand branches. Damage to the tree reduces pro-ductivity and increases susceptibility to winterinjury or attack by additional pests. SinceWisconsin is near the northern limit for stonefruit trees, disease management is critical to pro-duce quality fruit consistently. For specific recom-mendations on pesticide applications, seeExtension publication Apricot, Cherry, Peach, andPlum Pest Management for Home Gardeners(A2130).

Brown rotBrown rot is caused by a fungus (Monilinia fructi-cola) and is the most common disease of stonefruits in humid areas of the United States such asWisconsin. All stone fruits are susceptible tobrown rot, which damages flowers, twigs, andfruit. Warm, humid, and wet weather favor thedevelopment of brown rot. In years when theseconditions prevail, entire crops may be lost in justa few days.

Infected blossoms wilt and turn brown but per-sist into the season. Infected twigs show smallcankers that eventually expand and may girdlethe branch. This causes the new growth at theends of branches, or “terminal growth,” to die.Mature fruit are more susceptible to brown rotthan immature fruit. Initially, small, light brownspots develop on the fruit. Given favorableweather, these spots will expand rapidly and candestroy an entire fruit in only a few hours. Aninfected fruit may fall to the ground or persist onthe tree as a “mummy.”

Brown rot overwinters in these mummies, on thetree or on the ground. When warm, wet weatherreturns in the spring, the fungus ejects sporesfrom mummies and other overwintering sitessuch as branch cankers. The spores spread bywind and splashing rain, causing primary infec-tions of blossoms and twigs. Later, fruit areinfected by spores from mummies, infected flow-ers, and previously infected fruits. Injured fruitsare especially susceptible to infection.

Prevention and control. Management ofbrown rot begins by removing any infected fruit,mummies, and twigs from the tree and the sur-rounding ground immediately after harvest. Thisreduces the amount of overwintering fungus.Applications of fungicides, particularly early inthe season during flowering, is usually necessaryto manage brown rot. Additional applicationsbeginning about 3 weeks before harvest may benecessary under heavy disease pressure. Formore information see Extension publicationBrown Rot of Stone Fruits (A8NYDS2).

Cherry leaf spotLeaf spot is a major disease of both sweet andsour cherries in the Great Lakes area. It is causedby the fungus Blumeriella jaapii. A related speciesattacks plums. The disease first appears as smallpurplish spots on the upper side of leaves. Thespots then turn brown. Only a few lesions perleaf are required before a leaf will turn yellowand drop. Severe infections may lead to partial orfull defoliation of trees, which subsequently leadsto smaller crops of soft, watery fruit with lowsugar content. This is accompanied by a loss ofvigor, which predisposes trees to winter injury orattack by other pathogens.

The disease overwinters in infected leaves underthe tree. The release of spores from infectedleaves coincides with the emergence of tendernew leaves in spring. However, infection usuallydoes not occur until after petal fall, when minutepores on leaves and stems, called stomata, open.Infection occurs through the stomata. Once pri-mary infection has occurred, secondary spores


24

may spread from the underside of infectedleaves. With favorable conditions, secondaryinfection can continue until leaf drop in the fall.

Prevention and control. Removing fallenleaves from around cherry trees will break thedisease cycle by not allowing overwinteringspores to develop. If cherry leaf spot becomesestablished, treatment with fungicides at 10- to14-day intervals from petal fall to harvest is usu-ally required.

Perennial cankerPerennial canker (also called Valsa, Cytospora, orLeucostoma canker) is caused by the fungiLeucostoma cincta and Leucostoma persoonii. Thedisease is most severe on peach but also affectsapricots, cherries, and plums. Perennial cankercan kill limbs and entire trees. Cankers on trunksand branches are oval-shaped with swollen edgesand may ooze an amber-colored gum. Gumming,however, is not unique to this disease.

The fungi overwinter in cankers or dead wood.Fungal spores are released during cool, wetweather. Mechanical and winter injuries, insectwounds, and leaf scars provide sites for spores tocause new infections. When a tree is growing vig-orously, it produces a wall of callus tissue thatlimits canker expansion. However, when a tree isdormant or stressed, fungal growth is favoredand cankers enlarge.

Prevention and control. The most effectiveway to prevent perennial canker is to keep treesin good health. Prune out cankered tissue fromthe tree by cutting near the base of the branch.Remove infected material from the site. Do notplant new trees near cankered trees. Avoidmechanical damage from lawn mowers. Winterinjury can be minimized by applying white latexpaint to the southwestern side of trunks andlarge limbs. To promote wound healing, delayextensive pruning until spring when warm, dryweather is forecast.

Bacterial cankerBacterial canker is caused by two closely relatedspecies of bacteria (Pseudomonas syringae pv.syringae and pv. morsprunorum). The disease willaffect virtually any part of a tree. Branches andtwigs will have visible cankers that may ooze agummy material. Note that gumming is notunique to this disease. Infection is most severeduring prolonged periods of cool, wet weatherfollowing bloom. Severely infected leaves willhave reddish spots or a shothole appearance, andthe leaves may curl inward.

The bacteria overwinter in infected woody tis-sues. For infection to occur, there must be someopening for the bacteria to penetrate. The pre-ferred openings are leaf scars and bud scale scars.The bacteria are usually spread by windblownrainfall and pruning shears.

Prevention and control. Some cultivars aremore susceptible than others to infection, but youshould assume that all cultivars are susceptible.Removing cankers reduces the population of thepathogen. Spraying trees with copper compoundsin the spring before bloom and in the fall afterharvest can suppress the bacteria. However, cop-per can be toxic to plant tissues and should notbe applied to developing fruits. Training trees tohave wide crotch angles helps prevent cankers.

Bacterial spotMost apricot, peach, and plum cultivars are vul-nerable to bacterial spot, a widespread problemin the eastern United States. Bacterial spot mayinfect leaves, fruit, and tender shoots. Leaf symp-toms begin as small, angular, water-soaked areason the underside of leaves. Severely infected treesmay be defoliated, leading to stress and loss ofvigor. When fruit are infected early, deep pitsform in the flesh. Later infection of fruit results ina mottled skin.

The disease is caused by the bacteriumXanthomonas campestris which overwinters incankers on the trees. In the spring, when growthresumes, bacteria ooze out of the cankers andspread via wind-driven rain. The bacteria mustenter the plant through wounds, such as thosecaused by hail, or through a natural opening,such as a leaf scar. Periods of frequent rainfalland moderate temperatures favor developmentof the disease.

Prevention and control. Keeping trees ingood health by controlling other disease andinsect pests and fertilizing properly will help pre-vent infection. Some cultivars are more resistantthan others. Copper applications in the fall orearly spring may suppress the disease but willnot eliminate it.

Black knotBlack knot, caused by the fungus Apiosporina mor-bosa, can be a severe pest of plum and cherrytrees. It is commonly found on wild plums andcherries, and this is an important source of infec-tion even for backyard fruit trees. The mostnoticeable symptom of the disease is the produc-tion of dark brown or black swellings on thebranches of plum and cherry trees. The knotstend to be longer than they are wide. The fungusoverwinters in knots on infected branches. In thespring, the knots release primary spores, whichare carried by wind and rain to infect otherbranches. Water droplets on limbs and tempera-tures between 55°F and 77°F are required forinfection to occur. Several months later newknots will begin to appear on infected branches.

Prevention and control. Most cultivated,European-type plums and cherries are suscepti-ble to black knot. Inspect trees several times peryear for black knot and remove the lesions bypruning 3 to 4 inches below the infection.Fungicides applied to control brown rot or cherryleaf spot may help prevent infection, but spray-ing fungicides alone will not control the disease.For more information, see Extension publicationPlum and Cherry Disorder: Black Knot (A2588).

Crown gallCrown gall is caused by the bacteriumAgrobacterium tumefaciens. The pathogen persistsin the soil for many years and affects a widerange of herbaceous and woody plants. The bac-teria invade roots and crowns through woundssuch as those caused during planting or by insectdamage. The bacteria stimulate an over-production of plant hormones, causing tumorlikegalls that can grow to 4 inches in diameter. Thegalls are initially fleshy and white but becomefirm and tan to brown when the tree is dormant.

Prevention and control. There is no knowncontrol for crown gall. Therefore, to preventintroducing it into your soil, carefully inspect theroots and crowns of new trees for any abnormali-ties. Do not plant trees in soil where plants previ-ously had crown gall.

VirusesStone fruits are particularly susceptible toviruses. Viruses are very host-specific, so thosethat attack stone fruits will infect only stonefruits. Symptoms may range from yellowingleaves to dieback of terminal shoots to delayedbud break and leaf emergence to general stuntingand loss of vigor. While viruses may be impli-cated in maladies that cannot be explained byother means, do not assume your tree is virus-infected just because you can’t find anothercause. Tests are available to verify infection withcommon viruses.

Sucking insects such as leafhoppers are usuallyimplicated in the spread of viruses. When insectsfeed on an infected tree and then on an unin-fected tree they may pass the virus to the latter.Prunus necrotic ringspot virus can also be spreadby pollen. Wild Prunus species growing nearyour planting may harbor viruses which can thenbe carried into your trees. Some viruses arespread from tree to tree by root grafts. There isalso evidence that some viruses can be spread viapruning shears or other tools. Before virus index-ing programs were started at commercial nurs-eries, the nurseries spread viruses through the

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budding and grafting processes used to producetrees. Modern sanitation programs have largelyremoved viruses as a problem in commercialnurseries. This is an important reason to pur-chase trees from a commercial nursery ratherthan try to propagate your own.

Prevention and control. There are no cures forviruses in plants. If you have confirmed a viralinfection, the only remedy is to remove the plant.Otherwise, it can become a source of infection tonearby stone fruits.

PROBLEM SOLVING

Why stone fruit trees fail to bearStone fruit trees can fail to bear fruit for manyreasons—cold winter temperatures, spring frosts,poor pollination, age of trees, too much pruning,and too little training. This section describes themost common problems and how to avoid them.

Winter injury. Perhaps the most common prob-lem of peaches and sweet cherries is bud injuryfrom cold winter weather. Fruit buds are themost sensitive part of stone fruit trees. Wintertemperatures below 0°F will kill fruit buds, andtemperatures below about –10°F will injure or killthe trees. Planting on favorable sites is virtuallythe only method to help avoid winter injury.

Spring frosts. Another very common problemfor stone fruits is spring frosts. Temperatures ator below 30°F during or after flowering will killthe flowers and prevent fruiting. Apricots areparticularly susceptible to frost damage. Stonefruits generally flower earlier than apples orpears, so they are even more prone to spring frostinjury. Planting on only the best sites and plant-ing late-flowering cultivars will reduce the prob-lem. See the earlier section “Spring FrostProtection” for more information.

Pollination problems. Poor pollination may bedue to poor weather conditions during flowering.Bees or other insects are required for pollinatingstone fruit flowers. If the weather is cold, cloudy,windy, or rainy, bees do not forage well. Withoutinsects to transfer pollen, no fruit develop. Pollen

incompatibility is another problem. Table 1 liststhe pollination requirements of common stonefruits. If cross-pollination is required, a secondcompatible cultivar must be planted within 100yards to be effective. Sweet cherries also can becross-incompatible. Ask your nursery whatpollinizer will be effective for the main cultivaryou desire.

Tree age. Stone fruit trees must mature beforethey will produce fruit. The number of yearsrequired is not absolute. Some trees will bearfruit the year after planting, while others maytake 5 years to begin to bear. Be patient and elim-inate all other causes before implicating tree age.

Heavy pruning. Too much pruning, particularlyheading cuts into 1-year-old wood, causes treesto produce strong vegetative growth. Trees thatare vegetatively invigorated produce few flowerbuds. Heavy pruning can also remove flowerbuds once they have formed. Prune trees only asneeded to train the tree to the desired shape andto ensure good light distribution within thecanopy. Don’t prune trees with hedge shears orsimilar tools.

Poor training. Trees that have strongly verticallimbs will produce fewer fruit than limbs with amore horizontal orientation. Training branches togrow out, rather than up, will increase their fruit-fulness. See the “Training and Pruning” sectionfor advice on correcting the problem.

Too much fertilizer. Trees that receive toomuch nitrogen fertilizer produce excessive vege-tative growth. This growth comes at the expenseof fruit production.

Poor fruit qualityIn some cases stone fruit trees will produce fruit,but the fruit is of poor quality. This sectiondescribes several problems that may lead to poorfruit quality.

Fruit from rootstock. Most stone fruit treesare “two-piece trees,” composed of a rootstockand a scion. If the scion is killed but the rootstockcontinues to grow, the rootstock can producefruit. Such fruit will typically be inferior in size,


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color, flavor, and texture if it is edible at all.Occasionally nurseries fail to remove a tree whenthe scion’s budding or grafting was unsuccessful.If a stone fruit tree is girdled or dies back toground level, it is better to replace the tree thanto risk having the rootstock produce fruit.

Neglected plantings. Fruit quality sufferswhen trees are not properly trained, pruned andfertilized, or if diseases and insects are not man-aged. Trees may be defoliated prematurely, lead-ing to low vigor and poor fruit quality. In othercases diseases or insects may attack the fruititself, rendering it inedible.

Poor growing conditions. Trees planted inpoor sites will likely produce poor-quality fruit.Strong shade prevents trees from manufacturingsufficient carbohydrates to produce quality fruit.Windy sites may promote the growth of woodrather than fruit. Carefully consider site selectionbefore planting. For more information, see “SiteSelection and Preparation.”

Inferior cultivars. Inferior cultivars will pro-duce inferior fruit. Also, chance seedlings willlikely produce poor-quality fruit. Bush cherries,sand cherries, Nanking cherries, and cherryplums will not produce fruit of the same qualityas standard tart or sweet cherries. Of course,these species will thrive and produce fruit in coldclimates where conventional cherries won’tthrive. For the best chance of success, plant culti-vars recommended in this bulletin or Extensionpublications Home Fruit Cultivars for NorthernWisconsin (A2488) and Home Fruit Cultivars forSouthern Wisconsin (A2582).

Why plantings failPlant death is usually caused by a number of fac-tors interacting rather than by a single identifi-able cause. One injury may cause enough stressto allow other problems to kill the tree. Severalcommon reasons for tree death follow.

Winter injury. Peach and sweet cherry trees arenot reliably hardy in Wisconsin. Tart cherries,European and domestic plums, and apricots are

more winter hardy, but they can still be injuredby severe winter temperatures, particularly ifthere is no snow covering the ground.

Winter-injured trees may leaf out and flower inthe spring. The leaves may be small and narrowand a lighter green color than leaves of undam-aged trees. Once hot days begin, the tree will wiltand die. The layer beneath the bark (the cam-bium) is normally cream-colored but turns red-dish brown when damaged. Other winter-injuredtrees don’t leaf out or flower at all and appeardead from the onset of spring.

In less severe situations the trees appear healthybut weaken over time, and diseases are able toinvade and ultimately kill the trees. Bacterial dis-eases in Wisconsin stone fruits are frequentlyassociated with winter injury. You can minimizewinter injury by selecting hardy species and cul-tivars, planting on only the best sites, controllingdisease and insect pests, and allowing trees to“harden off” by not fertilizing after August 1 andnot pruning after August 15. Branches with nar-row crotches have tender wood that may neverharden off fully. Spreading young limbs to createwide crotches can improve winter hardiness.

Too much water. Stone fruit trees will not tol-erate “wet feet.” Poor soil drainage is common insoils with a high clay content and in low areas.Standing water or soil saturation lasting morethan three days during the growing season willlikely damage the roots. Water fills the pores inthe soil, depriving the roots of oxygen. Avoidthese problems by choosing sites with good soildrainage.

Too little water. Young stone fruit trees areparticularly susceptible to drought. When wateris scarce, roots cannot supply enough water toreplace that lost by the leaves through transpira-tion. Sandy soils can’t hold a lot of water and areparticularly drought-prone. Prevent droughtstress by watering regularly. Young trees shouldreceive 3 to 5 gallons of water per week.Irrigation also benefits older, bearing trees duringdry periods.

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Physical damage. Bark at the base of the trunkcan be damaged by small animals feeding in thewinter and by lawn mowers and string trimmers.If a complete ring of bark is removed so that thetree is girdled, death will occur shortly aftergrowth begins in the spring. If the tree is not gir-dled but a large portion of the bark has beenremoved, the tree will weaken but may survive.To prevent physical damage, keep the area aroundthe trunk free of grass and weeds. Don’t pilemulch materials there. This will prevent rodentsand rabbits from nesting and will make the treesless attractive as a food source. Keep vegetationaround the planting mowed short, particularly inthe fall. You can also wrap tree trunks with wiretrunk-guards made from an 18-inch square of1⁄4- or 1⁄ 2-inch mesh hardware cloth. For moreinformation about rodent control, see ExtensionpublicationMeadow Mouse Control (A2148).

Deer will also feed on fruit trees. They tend to eatthe tips of shoots in late winter or early spring.When deer browse trees heavily, it is difficult totrain and prune trees correctly. Deer may alsorub against young trees, scraping off the barkand killing the tree. If deer pressure is heavy,only fencing will keep them away from trees. Butif deer pressure is light, repellents can reduce oreliminate injury. Inexpensive repellents includehuman hair or slaughterhouse tankage hung infabric net bags in each tree. Small, hotel-size barsof soap can also be effective repellents. Leave thewrapper on the bar and poke a hole through thesoap, then hang it on the tree with a short pieceof wire. All repellents last only a few weeks to afew months and need to be replenished often.For more information see Extension publicationControlling Deer Damage in Wisconsin (G3083).

Insect and disease pests. Severe insect ordisease infestations will not only make the fruitunusable but may defoliate trees. This is particu-larly true late in the year. Thus, severely diseasedtrees go into winter under stress that may lead towinter injury. While these problems seldom killtrees outright, they often contribute to death.Manage pests using the practices described in thesections “Insect Pests” and “Diseases.”


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G LOSSARY

Branch collarA slightly raised ring of tissuewhere a branch joins the trunk.When pruning be sure to leavethe branch collar.

CambiumA layer of quickly dividingcells, between the wood andbark in trees, where newgrowth appears.

CankerA localized diseased area, fre-quently roundish to oblong,surrounded by healthy tissue.

Central leaderThe main vertical branch of afruit tree.

CultivarA contraction of “cultivatedvariety” used to describe differ-ent varieties within a plantspecies.

Extension growthGrowth at the ends of shootsresulting in length, not girth.

GirdleTo remove a complete circle ofbark from a tree thus stoppingthe flow of nutrients from thetop of the tree to the roots.

Harden offThe process of adapting frommild growing conditions tomore rigorous conditions, as inthe autumn.

Heading cutA pruning cut that removes aportion of the length of a branch.Compare to thinning cut.

InoculumA pathogen or pathogen partthat infects plants.

MummyDried or shriveled fruit thatmay host pathogen inoculum.

PollinatorThe agent of pollen transfer, forfruit trees usually an insect.

PollinizerThe plant that is the sourceof pollen transferred by the pol-linator.

RootstockThe below-ground portion offruit trees. Rootstocks are usu-ally genetically distinct fromthe scions (the abovegroundportion) to which they aregrafted.

ScaffoldA lateral branch arising fromthe main trunk or leader, form-ing, along with other scaffolds,the framework of the tree.

ScionThe aboveground portion offruit trees that is grafted orbudded to a rootstock.

StomataSmall openings in leavesthrough which water exits (thetranspiration process) and car-bon dioxide enters.

SuckerA rapidly growing shoot aris-ing from the roots or rootstock.

Terminal growthGrowth from the end of abranch.

Thinning cutRemoving an entire branch atits point of origin on the trunkor a scaffold. Compare to head-ing cut.

TierOne of two or more levels ofbranches, each level arrangedone above the other.

Water sproutA rapidly growing shoot, usu-ally unbranched, growing onthe trunk or scaffold limbs.

Whip treesTrees from a nursery that haveno branches.

Winter hardyCapable of surviving wintertemperatures encountered inthe planting area.

RELATED PUBLICATIONSApricot, Cherry, Peach, and Plum Pest

Management for Home Gardeners(A2130)

Commercial Tree Fruit SprayGuide (A3314)

Common Tree Fruit Pests(NCR063)

Controlling Deer Damage in Wisconsin (G3083)

Diseases of Tree Fruits in the East (NCR45)

Fruit Crop Pollination (A3742-E)

Home Fruit Cultivars for Northern Wisconsin(A2488)

Home Fruit Cultivars for Southern Wisconsin(A2582)

Organic Soil Conditioners (A2305)

Meadow Mouse Control (A2148)

Plum and Cherry Disorder: Black Knot (A2588)

Rootstocks for Fruit Trees in Wisconsin (A3561)

Sampling Lawn and Garden Soils for Soil Testing(A2166)

Copyright © 1998 by the Board of Regents of the University of Wisconsin System doing business asthe division of Cooperative Extension of the University of Wisconsin-Extension. Send inquiries aboutcopyright permission to: Manager, Cooperative Extension Publishing, 103 Extension Building, 432 N.Lake St., Madison, WI 53706.

Authors: Teryl Roper is professor of horticulture, Dan Mahr is professor of entomology, and PattyMcManus is professor of plant pathology, College of Agricultural and Life Sciences, University ofWisconsin-Madison and University of Wisconsin-Extension, Cooperative Extension.Produced by Cooperative Extension Publishing. Pruning illustrations and graphic design by Jody Myer.Cover illustration by Catherine Baer, copyright 1998. Japanese beetle illustration by Dave Shetlar.

University of Wisconsin-Extension, Cooperative Extension, in cooperation with the U.S.Department of Agriculture and Wisconsin counties, publishes this information to further the purposeof the May 8 and June 30, 1914 Acts of Congress; and provides equal opportunities and affirmativeaction in employment and programming. If you need this material in an alternative format, contact theOffice of Equal Opportunity and Diversity Programs or call Cooperative Extension Publishing at608-262-2655.

This publication is available from your Wisconsin county Extension office or from CooperativeExtension Publishing. To order, call toll free 877-947-7827 (WIS-PUBS) or visit learningstore.uwex.edu.

A3639 GROWING APRICOTS, CHERRIES, PEACHES, & PLUMS IN WISCONSIN

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