GROWING SOUR CHERRIES

Agriculture Handbook No. 451

_^ ^,, ,,.. r^^-= ;::o-

§5 ^SP3 CO

Agricultural Research Service UNITED STATES DEPARTMENT OF AGRICULTURE 414275 PRECAUTIONS Pesticides used improperly can be injurious to man, animals, and plants. Follow the directions and heed all precautions on the labels. Store pesticides in original containers under lock and key— out of the reach of children and animals—and away from food and feed. Apply pesticides so that they do not endanger humans, livestock, crops, beneficial insects, fish, and wildlife. Do not apply pesticides when there is danger of drift, when honey bees or other pollinat- ing insects are visiting plants, or in ways that may contaminate water or leave illegal residues. Avoid prolonged inhalation of pesticide sprays or dusts; wear protective clothing and equipment if specified on the container. If your hands become contaminated with a pesticide, do not eat or drink until you have washed. In case a pesticide is swallowed or gets in the eyes, follow the first aid treatment given on the label, and get prompt medical attention. If a pesticide is spilled on your skin or clothing, remove clothing immediately and wash skin thoroughly. Do not clean spray equipment or dump excess spray material near ponds, streams, or wells. Because it is difficult to remove all traces of herbicides from equipment, do not use the same equipment for insecticides or fungicides that you use for herbi- cides. Dispose of empty pesticide containers promptly. Have them buried at a sanitary land-fill dump, or crush and bury them in a level, isolated place. NOTE: Some States have restrictions on the use of certain pesticides. Check your State and local regulations. Also, because registrations of pesticides are under constant review by the Federal Environmental Protection Agency, consult your county agricultural agent or State Extension specialist to be sure the intended use is still registered.

ni CONTENTS Page Climatic requirements 2 Soil requirements 5 Cultivars 6 Pollination requirements 8 Propagation and rootstocks 8 Selecting and handling nursery trees 9 Orchard planting 10 Site 10 Time of planting 11 Tree spacing 11 Transplanting 12 Tree heading and training 14 Care of young trees 15 Orchard management 16 Tillage and cover crops 16 Fertilization 17 Intercrops . 18 Irrigation 18 Pruning 19 Thinning fruit 19 Harvesting 20 Packing 24 Processing 24 Virus diseases 24 Ringspot 24 Sour cherry yellows 25 X-disease 26 Pink fruit 26 Other virus diseases 27 Fungus diseases 27 Leaf spot 27 Brown rot 28 Other diseases 28 Insects 29 Black cherry aphid 29 Plum curculio 29 Fruit flies 30 Pearslug 30 Literature cited 31

Washington, D.C. Issued March 1974 For sale by the Superintendent of Documents, U.S. Government Printing Office, Washington, D.C. 20402 - Price 40 cents Stock Number 0100-02892 IV V5~/, y.I. /iM ff 7^/

' GROWING SOUR (MERRIES>/^, ifa

By H. W. FOGLE, L. C. COCHRAN, and H. L. KEIL*

The sour cherry {Prurms cer- to produce Duke cherries (P. asus L.) also is referred to as the gondouinii (Poit. & Turp.) Rehd.) tart, pie, or red cherry. Like the (19, i6), Duke cherries are tetra- sweet cherry (P. avium L.) it ploid and intermediate between is a drupe or stone fruit belong- the parent species. Some of these ing to the family Rosaceae. It is are very similar to sour cherries a tetraploid species (47i=32), in fruit characteristics but have which apparently is native to the upright growth habit. Caspian-Black Sea region and Approximately 6 million sour perhaps to northern India (22, cherry trees of bearing age and U7, 61, 66)? It is considered a another million trees not of bear- natural cross of P. fruticosa ing age were grown throughout Pall., also tetraploid, with unre- the United States according to duced pollen of P. avium, a dip- the 1964 census. They were dis- loid species {63), Occasionally tributed in every State. Michigan the sour cherry hybridizes with had about 4.2 million trees, or unreduced pollen of sweet cherry 62 percent of the total. Wiscon- sin had about 825,000 trees, New 'H. W. Fogle, horticulturist, and H. L. Keil, plant pathologist. Fruit Lab- York about 750,000 trees, and oratory, Northeastern Region, Agricul- Pennsylvania about 340,000 trees. tural Research Service, and L. C. The remainder were distributed Cochran, professor of plant pathology. primarily in States bordering the Department of Botany and Plant Pa- Great Lakes and in the North- thology, Oregon State University, Cor- western and Rocky Mountain vallis. The authors acknowledge the gen- States. erous use of text and illustrations from In the 1969 census about 4.8 Farmers' Bulletin 2185, "Growing Cher- million bearing trees and 0.9 ries East of the Rocky Mountains," million nonbearing trees were re- prepared by the late Leon Havis. This ported, reflecting a continued de- bulletin is out of print. Figure 2 was furnished by T. K. Toyama, Irrigated cline in total acreage. Agriculture Research and Extension The most important commer- Center, Prosser, Wash., figures 3, 7, 8, cial sour cherry orchards are lo- and 12 by Cornell University, Ithaca, cated in western Michigan, wes- N.Y., and figure 16 by Friday Tractor Co., Hartford, Mich. tern New York and the Hudson * Italic numbers in parentheses refer Valley, southern and northwes- to Literature Cited, p. 31. tern Pennsylvania, Door County AGRICULTURE HANDBOOK 451, U.S. DEPT. OF AGRICULTURE of Wisconsin, Oregon, Utah, The bulk of the sour cherry Arkansas River Valley of Colo- crop is frozen (about 55 percent) rado, and northern Ohio. Large or canned (about 40 percent) quantities of sour cherries are for use in pastries, primarily produced in some other States, pies. Small quantities are used but usually the individual or- for juice, jam, or jelly and for chards are small and do not rep- brining. Some of these uses are resent important community included in the total for canning. interests. Sour cherries often pro- Only about 3 percent of the crop duce well in the central and is sold fresh, and this is declin- southern Great Plains regions, ing (35). where more tender fruits usually fail. Annual sale value of sour cher- U.S. production of sour cher- ries in the United States is about ries varies from about 90,000 to $20 million. over 175,000 tons annually (table Production is relatively stable 1). Michigan produces from 50 (2i) and is predicted to remain to over 70 percent of this ton- so (79); however, acreage has nage, and combined with New declined in States where mech- York, Pennsylvania, and Wiscon- anical harvesting has not been sin up to 90 percent. adopted.

CLIMATIC REQUIREMENTS Climate, chiefly temperature, A sudden freeze after a mild is the most important factor af- period sometimes causes dormant fecting the geographic distribu- trunks to split. Often these splits tion of sour cherry trees (32), close tightly and little damage Generally the trees do not thrive ensues. However, sometimes bark where summers are long and hot and cambial tissues are injured or where winter temperatures are and repair of the large wounds high for short periods. Primarily requires several years. (Fig. 1.) because of this, few sour cherries Sour cherry trees usually are are grown in the South; how- less hardy than 'Mclntosh' and ever, some are grown at higher 'Northern Spy' apple trees, but altitudes. Young sour cherry trees are more hardy when fully dor- respond to longer day length di- mant than other stone fruit trees rectly by increased shoot growth of commercial importance except but less so as they become older the European plum (Prunus (W^ domestica L.). Early fall freezes Winter injury to trunks is a before the trees become fully serious problem in some central hardened may damage trunks and southern parts of the country. and crotches in northern produc- GROWING SOUR CHERRIES

oooooooo eoo O O O O O lA O |SOOCOOO(NCOlß tXOO

,ÔOOO<Î>00000 ^OOO'^ÓOO^OIOO

"o TH rH ^ s CO so 5'

CO 000000Tí<0 OOOOOO00 ÇO TH Tí< TH iH i o iH O W coOOOOOOOOOO SÓTHOOOOi^rH^ la ^^r^^ ^ TdT C^ TH ^ CO l> iH TH .S ë p.

eoÓOOÓOOOÓOOO gOOOÓOOOOOlAO g OiAOl>OC0Ó0t- 05 ^ t- (N E-H IÍ5 çfT 00 t> t> oí

P4 OOOÓOOÓOOOO COOOOOiOOOOOOO'^ ÇÎOrHLAOC0t>l>'^'^iA tH

C'^OlACÍOOíNCOTHrHTH V.^ U.W V.>l o H (M Oa rH

OOOOOOCOOCOOOO C9O"^Cs|Ç0Ç£>O00t-Ç0"^t> 5:t> ooc^'^'^o

tí o o 2 'S «? 2 2^ 2 ß 5 « ê ^ feo S ;z; PH ^ O t) O 4 AGRICULTURE HANDBOOK 451, U.S. DEPT. OF AGRICULTURE

ing areas {3, 37, A2). Extremely low winter temperatures may kill flowerbuds and damage terminal wood and spurs (fig. 2). The blossoms and young fruits of sour

PN-2947 FIGURE 2.—Browning of tissues in fruit spur and fruit buds of cherry in Yakima Valley of Washington State after -11° F. in November 1964.

cherries are very susceptible to PN-2946 injury by low temperatures. FIGURE 1.—Trunk of 'Montmorency' Protection against temperatures cherry, showing winter injury. This below 28° F. is advisable after the type of injury is often caused by buds reach the green tip or so- rapid changes in temperature. The called water bud stage (Dennis, injury to this tree occurred several F. G., et al., unpublished). Often years before the photograph was taken, and considerable healing had more blossoms and fruits, are kil- taken place, as indicated by new bark led by spring frosts oh sour along the right side of the wound. cherry than on peach trees in the same area. GROWING SOUR CHERRIES

SOIL REQUIREMENTS Sour cherry trees will grow cherry-growing areas the prevail- on a wide range of soil types ing soils are sandy loams or other provided the soils are well sandy soils that usually are under- drained. Perhaps no other fruit lain by clay subsoil. Such soils tree is more sensitive to the ill occur in districts bordering the effects of a poorly drained soil Great Lakes, where the most im- (fig. 3). In many important portant commercial cherry areas

PN-2948 FIGURE 3.—'English Morello' trees 6 years old, showing effect of soil drainage: A, On poorly drained soil ; B, on well-drained soil. These trees were within 33 feet of each other, and the camera was at the same distance from each. 6 AGRICULTURE HANDBOOK 451, U.S. DEPT. OF AGRICULTURE east of the Rocky Mountains are Since the heavier clay soils often located. However, the industry are insufficiently drained, the has developed in these districts lighter soils are preferred for because of the tempering effect cherries. of large bodies of water instead Soils that are droughty and of the existence of particular soil that dry out excessively are un- types. satisfactory for cherry trees. Many of the better orchards Moderately fertile soils give bet- in western New York are on ter results than those having Dunkirk clay loam, which is either extreme in fertility. fairly heavy but well drained.

CULTIVARS Sour cherries are separated in order of their introduction into two distinct groups based are 'McClain Montmorency' on the color of the fruit juice— (1925), 'Montearly' and 'Mont- the Amarelle or Kentish group late' (1932), 'Musselman Mont- with colorless juice and the Mor- morency' (1934), 'Gilbert Mont- ello or Griotte group with reddish morency' and 'Jordan' (1937), juice and usually dark-red fruit 'Richmorency' (1938), 'Bell Mont- {Si, ^7). In addition, a subspe- morency' (1940), 'Montmorency, cies classification is sometimes Dayton strain' (1941), and 'Fern- given to the Marasca group, which wood Montmorency' ( 1956). is used for distilled or brined 'Black Flame', introduced in 1940, products {61), Further classifi- is an open-pollinated seedling of cation into Montmorency, Mor- 'Montmorency' {9). ello, Brüsseler, and Vladimir A 1961 survey showed that groups has been suggested {66), 70 distinct cultivars and num- About 270 named cultivars erous selections or mutations of (varieties) of sour cherries were 'Montmorency' were growing in described by Hedrick in 1914 North American fruit collections (47). Only 12 had been added by {33), Only three cultivars are of 1950 and an additional five by economic importance—'Mont- 1970. Ten of these 17 were muta- morency', 'English Morello', and tions of 'Montmorency' {9). 'Early Richmond'. 'Montmorency' Numerous mutations or strains is by far the leading cultivar. of 'Montmorency' have been se- These cultivars are described in lected for productiveness, season order of fruit ripening as fol- of fruit maturity, or disease re- lows: sistance {18, 39y U), The fruits 'Early Richmond' (Kentish) of these are similar to those of apparently originated in the 'Montmorency'. These mutations Montmorency Valley of France GROWING SOUR CHERRIES and was introduced into America ing and sometimes drooping. An- via either England or Holland nual terminal growth often is W). Fruits are light red, small short and trees become unproduc- to medium sized, white fleshed, tive. They are particularly sus- of fair quality, and ripen 7 to ceptible to the leaf spot fungus 10 days before 'Montmorency'. ( Coccomyces hiemalis Higgins ). Trees are medium sized, moder- 'Meteor', introduced in 1952, ately productive, and relatively was derived from a cross of hardy. Early strains of 'Mont- 'Montmorency' and a seedling de- morency' are supplanting this rived from 'Vladimir' and 'Shub- cultivar. ianka' at the University of Min- 'Montmorency' originated in nesota Fruit Breeding Farm (9). the Montmorency Valley of This cultivar combines improved France before the 17th century winter hardiness with relatively (^7). Fruits ripen in midseason small Montmorency-type fruit. and are relatively large, bright 'Coronation', introduced in 1937 red, white fleshed, and of good by the Dominion Experimental quality. Trees are vigorous, hardy, and very productive on good soil. Station, Morden, Manitoba, and The firm flesh and long harvest 'Dwarfrich', introduced in 1952 season make this cultivar the by the U.S. Horticultural Field best suited for processing uses. Station at Cheyenne, Wyo., are Mutations in this cultivar have open-pollinated seedlings of made available a succession of 'Vladimir' (9). Both have bush- similar types that permits a pro- type, dwarfish growth. longed harvest season and more 'Northstar', introduced in efficient use of harvesting ma- 1950, was derived from a cross chinery and labor. Usually this is of 'English Morello' and 'Serbian the only sour cherry cultivar Pie No. 1' at the University of grown by the most successful Minnesota Fruit Breeding Farm orchardists. (P). It has Morello-type fruit 'English Morello' is thought and usually a very dwarfed, hardy to have originated in Holland or tree. This cultivar has potential Germany and then was intro- as a dwarfing interstock for sweet duced into England and France cherries. (^7). Fruits ripen 10 to 14 days Other cultivars generally have after 'Montmorency', and are a limited availability. Detailed medium sized, very dark red, descriptions of those originating and very tart, but of good quality. before 1920 are given by Hed- The flesh is dark red and the rick (^7) and later ones by juice is red. Trees are spread- Brooks and Olmo (9), g AGRICULTURE HANDBOOK 451, U.S. DEPT. OF AGRICULTURE

POLLINATION REQUIREMENTS

All commercially important A few minor cultivars, viz sour cherry cultivars are con- 'Chase', 'Ostheim', 'Kentish Red', sidered self-fertile and pollinizers 'Homer', and a few mutations of usually are not planted (31, 8i). 'Montmorency' give higher fruit Under favorable conditions, i.e., sets from cross-pollination than weather warm enough for bee from self-pollination (17, SI), activity and for pollen tube Factors may be involved, such growth, and adequate nutrition, as those that make all commer- pollen from an individual tree cial sweet cherry cultivars self- will fertilize the pistils of the incompatible (16). flowers on the same tree and Prolonged periods of cool wet cause fruit set. Low light inten- weather during blossoming may sity does not appear to hamper prevent fruit set because of in- fruit set (ii). However, bees or adequate pollination. However, other insects apparently are relatively short periods of warm necessary for transporting the temperatures and intense bee pollen, regardless of the com- activity may insure a good crop patibility factors. if the anthers are shedding pollen.

PROPAGATION AND ROOTSTOCKS

Most growers buy trees from stocks (70), Despite occasional a reputable nurseryman. Trees incompatible unions, mahaleb are propagated by budding on rootstocks are usually satisfac- seedling stocks in the nursery tory. Trees on this stock in good row and sold for transplanting soil are more productive than to the field when they are 1 or 2 those on mazzard (i). However, years old. It is essential that the mazzard rootstock is more nurserymen use budwood only desirable for heavy soils. 'Stock- from trees that are free of known ton Morello' rootstock sometimes viruslike diseases. Likewise, trees is used in areas with inadequate producing seeds for rootstock drainage (21), should be free of known viruses. Two kinds of seedling root- Trees on mahaleb rootstock ap- stock are in general use—the pear more spreading than those mahaleb and the mazzard (1, í, on mazzard in the early bearing 8, H, 15, 21, i5, JÍ8, 70, 78), The years, probably because those on mahaleb is used more extensively mahaleb grow more slowly and than the mazzard for sour cherry bear fruit when they are younger. GROWING SOUR CHERRIES 9

SELECTING AND HANDLING NURSERY TREES

Either 1- or 2-year-old nursery able, but smaller trees often are trees may be used. Medium-sized satisfactory (fig. 4). Unpack trees, 4 to 5 feet high and nine- trees immediately after delivery sixteenths to eleven-sixteenths and keep the roots moist. The inch in diameter, seem prefer- trees should be heeled in (fig. 5)

PN-2949 FIGURE 4.—Sour cherry trees representing different grades of nursery trees as follows: A, 2-year-old 'Montmorency' on mazzard rootstock, three-fourths inch or more in diameter, 5 to 7 feet high; B, same as A except on mahaleb root- stock; C, 1-year-old 'Montmorency' on mazzard rootstock, five-eighths to eleven- sixteenths inch in diameter, 3 to 4 feet high; D, 1-year-old 'Montmorency' on mahaleb rootstock, five-eighths to eleven-sixteenths inch in diameter, 3 to 4 feet high. 10 AGRICULTURE HANDBOOK 451, U.S. DEPT. OF AGRICULTURE

PN-29B0 FIGURE 5.—Cherry trees heeled in. if they cannot be planted im- in, they usually are placed in mediately. parallel rows. When this is done, A place where the soil is fri- the roots in one row may be able, deep, and well drained covered with the soil that is re- should be used for heeling-in the moved in opening the adjacent trees. Make a trench sufficiently trench. Trees that are tied in wide and deep for the roots and bundles when received must be lay the trees at an angle. Then separated before they are heeled- distribute moist sawdust, bark in. If this is not done, it is dif- dust, or soil among the roots to ficult to distribute the soil among fill all the spaces between them. the roots sufficiently to protect If many trees are to be heeled- them from drying.

ORCHARD PLANTING Site ing blossoming. Heating of sour cherry orchards usually is not The area of land occupied by profitable. Because cold air set- the trees is called the "site." The tles to lower levels, orchards oc- most essential site considerations cupying sites slightly higher than are soil and local climatic condi- the surrounding areas are usually tions. Cherries blossom compara- less likely to be injured by frost tively early in the spring. Avoid than those at comparatively low sites subject to spring frosts dur- elevation. Also, the soil on higher GROWING SOUR CHERRIES 11 levels is likely to be better a 6-foot-wide strip in the tree drained. row need be prepared. Since soil Replanting favorable sites with preparation will vary with the sour cherries may lead to un- location and soil type, follow lo- thrifty growth. Preplant fumi- cal recommendations. gation of a problem site in Michigan increased trunk growth, even of diseased trees (55). Root Tree Spacing lesion (Pratylenchus sp.) and Cherry trees are planted at dagger nematodes (Xiphinema various spacings depending on sp.) were present in the orchard. the topography of the land, soil Avoid soils in which tomatoes, depth, rootstock, varietal char- potatoes, or other solanaceous acteristics of the trees, and pref- crops have been grown during erence of the individual grower. the previous 5 years because of Sometimes smaller trees, such as the verticillium wilt hazard. 'English Morello', are planted 16 Turning under a green man- to 18 feet apart each way. The ure crop is a good way to pre- minimum spacing of permanent pare a site. trees for most sour cherry culti- vars is 20 feet apart. The spacing Time of Planting may be increased up to 24 feet Cherry trees should be planted if the soil is favorable for tree as soon as possible after they growth, particularly for vigorous are dug to prevent losses of cultivars such as 'Montmorency'. young orchard trees. If feasible, The square system is generally obtain and plant trees in the used in planting cherry trees. fall. In areas where winters are However, a contour system extremely severe, spring plant- should be considered on sites ing is advisable. In the middle where there is danger of soil latitudes and where winters are erosion. Contour planting means comparatively mild, fall planting planting each row of trees at the usually is preferable and it is same level or on a contoured line becoming more common in areas with a slight grade along which where the climate is moderate. water moves slowly. Sometimes The trees should be completely terraces are desirable. In contour dormant prior to planting to pre- planting, there should be a min- vent bud growth. Extensive bud imum distance of about 18 feet growth prior to planting usually between rows. increases tree losses. Soil and moisture conservation Prepare a good seedbed for the are essential for best production. trees. Plowing or deep disking The extra time required to plan usually is necessary. Where ero- and lay out a good conservation sion is a potential problem, only system is well spent. 12 AGRICULTURE HANDBOOK 451, U.S. DEPT. OF AGRICULTURE

The undesirable effect of plant- Transplanting ing too closely is illustrated in The details of planting are figure 6. The 21-year-old 'Mont- similar to those usually followed morency' trees are spaced 14 by for apples, peaches, or other 14 feet since the filler trees were fruit trees commonly planted in not removed. The long, slender, sections where cherries are upright branches interlock, caus- grown. ing spraying and harvesting prob- When a tree is being prepared lems. for planting, remove all mutilated On well-drained, fertile soil, or injured parts of the roots. 'Montmorency' trees may become Cut long, slender roots to match crowded even when spaced more the length of the main roots. than 20 feet apart, and some of Take every precaution to pre- the trees may need to be removed vent the roots from becoming for best orchard operation. The dry. The tree roots will be in- trees in figure 7 are too close; jured if they are unduly exposed those in figure 8 are well spaced. to cold or to drying-out during

V i^rf- JA-}'_,', ■^ -jè^:

'^ ■*W

PN-2951 FIGURE 6.- -This 'Montmorency' cherry orchard in New York is about 21 years old and the trees are 14 feet apart each way. They are tall with long slender branches as a result of being planted too closely. GROWING SOUR CHERRIES 13

PN-2952 FIGURE 7.—Twelve-year-old 'Montmorency' trees. The permanent trees are planted 24 by 24 feet on a square system, and a semipermanent tree is in the center of the square. These trees on mazzard stocks and in good soil are too close together.

PN-2953 FIGURE 8.—Well-spaced trees in a 'Montmorency' cherry orchard. The semi- permanent trees were removed when 12 years old. 14 AGRICULTURE HANDBOOK 451, U.S. DEPT. OP AGRICULTURE trimming and planting. Many poor stands of cherry trees have resulted from injury to roots ex- posed prior to planting. Use only pulverized topsoil around the roots in filling the hole after a tree has been put into position and alined. Work the soil in closely around the roots. Moving the tree up and down slightly as the hole is being filled helps settle the soil among the roots. As the filling progres- ses, firmly tamp the soil around the roots and fill the hole to the surface. If water is available, fill the hole with water when it is about two-thirds filled with soil and completely fill it with A A^^^f!t^ soil several hours later. BvÄi:iï^*

PN-2954 Tree Heading and Training FIGURE 9.—One-year-old 'Montmorency' cherry tree, about 3 feet high, show- Sour cherry trees have ing method of pruning at time of a spreading habit of growth. The planting: A, Before pruning; J5, after pruning. modified-leader system of train- ing is preferable for all types. scaffolds should be at least 4 to Both well - grown 1-year-old 6 inches apart up and down the and 2-year-old trees should be trunk. If all are allowed to de- branched when received from the velop from the same height, a nursery. Select about four weak tree is likely to result (figs. branches for main or scaffold Hand 12). limbs of the tree (figs. 9 and 10). For these scaffold limbs, re- The lowest scaffold limb should tain only branches with the widest start at least 14 to 16 inches angles. Select the more vigorous from the ground. The others branches and cut back to about should be well spaced around the the length of weaker ones so that trunk up and down so that none all may develop to approximately are directly over a lower one. For equal length. Do not cut back the mechanical shaking, the lowest main stem or trunk when it is branch should be at least 18 and planted; it should be left higher preferably 24 to 30 inches from than any of the scaffold branches ground level. Where possible, the (figs. 9 and 10). GROWING SOUR CHERRIES 15

PN-29B6 FIGURE 11.—'Montmorency' cherry tree with no leader and all scaffold limbs arising at the same height. The left limb is very weak at the crotch and is likely to break and leave a large wound on the trunk. PN-2955 FIGURE 10.—'Montmorency' tree grown 2 years in the nursery. It is about 4 feet high and pruned properly for setting in the field. Note that the original leader was cut back after 1 year in the nursery, but the lateral branch selected as a leader was not cut back.

Care of Young Trees In areas of low or poorly dis- tributed rainfall, newly planted trees should receive supplemental irrigation to avoid moisture stress PN-29B7 (53). Competition for nutrients FIGURE 12.—Eight-year-old cherry tree, showing type of scaffold-limb break- or moisture from weeds or cover age common on cherry trees on which crop should be prevented. If a several limbs are allowed to develop cover crop is used, maintain a at the same height. clean-cultivated strip of about 18 inches on each side of the tree mental nitrogen sparingly as the row or a 3-foot circle around each need is indicated by inadequate tree. In general, do not use chem- terminal growth or pale-green fo- ical weed killers during the first liage. However, fertilizer usually summer of growth. Apply supple- should not be applied after mid- 16 AGRICULTURE HANDBOOK 451, U.S. DEPT. OF AGRICULTURE

July to avoid growth late in the areas, potassium solutions are ap- fall and subsequent winter injury plied at planting time to prevent to unhardened tissues. In some potassium deficiency (60).

ORCHARD MANAGEMENT Orchard management practices crop is seeded at the last culti- vary with soil types, drainage, vation, at about the time the fruit availability of irrigation, and is harvested, and it is disked down many other factors (3, 28, 38, early the following spring. Cherry M, 51, 52, 53, 61, 67, 68, 7U). growers sometimes allow weeds to Cost estimates for some of these grow as a cover crop during the practices in sour cherries are not late summer and fall. However, a available, but some are similar to planned cover-crop system is of- estimates for sweet cherries {73). ten necessary to prevent erosion in sloping orchards. Tillage and Cover Crops Mechanical or chemical weed control in a strip 3 to 4 feet wide Cherry orchards usually are in the tree rows and periodic given clean tillage with a disk har- mowing or flailing of the sod row during the early summer or strips between tree rows over- until about the middle of July. come the disadvantages of com- The clean-tillage practices of vari- plete cover in orchards requiring ous growers differ greatly. Some continuous cover crops. Usually a growers cultivate their orchards low-growing nonlegume such as weekly when the trees are grow- bluegrass and fescue or a shallow- ing rapidly, others cultivate three rooted legume such as subterran- or four times during the entire ean clover (Trifolium subterran- season, and some use chemical eum It.) adapts best to this weed control. The tendency is to- cultural system. ward less tillage and even non- Cover crops have additional ad- tillage. The latter combines chemi- vantages. They improve aeration cal weed control with mowing. in clay soils, increase water-hold- Cover crops in the early sum- ing capacity, and aid in retaining mer, when most tree growth oc- the nutrients in sandy soils. They curs, may compete seriously with utilize excess nitrogen in late the trees. The rapidly growing summer and may aid in harden- fruits and shoots require large ing of trees by preventing late amounts of moisture and soil nu- flushes of growth and subsequent trients. A more continuous cover winter injury. The type of cover crop may be necessary if there is crop used and the method of man- danger of soil and water loss aging it vary in different dis- from erosion. Usually a cover tricts and sometimes even on dif- GROWING SOUR CHERRIES 17 ferent farms in the same area applications to individual trees {51 y 52). from the average indicated rate In many localities, one of the according to the amount of ter- best cover crops for cherries is minal growth and the leaf appear- rye, which is sown in late sum- ance. mer at the rate of about IVè The fertilization procedure for bushels per acre. The cover crop cherries is similar to that for should be disked or mowed well other orchard trees {77). Ade- before it matures in the spring to quate but not excessive amounts prevent competition with the of the major elements contribute trees. Some growers prefer a late- to fruit firmness {20). Cherries summer crop that does not sur- usually respond well to nitrogen- vive the winter, such as oats, ous fertilizers such as sodium ni- millet, or buckwheat. trate, urea, ammonium sulfate, Sometimes cherry orchards can and ammonium nitrate. Because be maintained satisfactorily in of differences in the soil, no def- sod if adequate nitrogen is ap- inite amount to apply can be plied. However, the trees may suf- stated {67). In general, one-half fer from lack of moisture unless pound of sodium nitrate or equiv- the soil is deep. A mulch of straw, alent amount of other fertilizers, hay, or similar material around based on actual nitrogen content, the trees reduces evaporation and for each year of the tree's age allows better root development may be used. For example, a 6- in the surface soil. Trees grow year-old tree would be given 3 best without competition, and a pounds of sodium nitrate or I14 continuous sod should be consid- pounds of ammonium nitrate, ered only when necessary to pre- since the latter contains twice as vent erosion. Where bluegrass is much nitrogen as the sodium ni- adapted, it is one of the best sods ; trate. Usually the application of in other areas the native grasses, any other element is not neces- lespedeza, and other legumes may sary, but cherry trees in a few be used. areas have responded to potassium {60)y and in Oregon some orch- Fertilization ards are deficient in boron. A soil test may be useful in The fertilizer should be spread determining the average initial uniformly under and around the fertilizer application necessary. trees to just beyond the dripline Likewise, leaf analysis services of the branches. Apply nitrogen may be utilized periodically to fertilizer in either the fall or the monitor the general level of nutri- early spring. ents in an orchard. However, Usually it is necessary to apply the most economical fertilization more fertilizer to trees grown in system may be to vary the annual sod than to those that are clean 18 AGRICULTURE HANDBOOK 451, U.S. DEPT. OF AGRICULTURE cultivated. Application of a com- before the trees become crowded. plete fertilizer, such as 10-10-10, Substantial crop reduction for 1 at the rate of about 250 pounds or more years will result from de- per acre when the crop is planted, layed removal of "filler" trees. is often valuable in establishing a vigorous cover crop. Trees in Irrigation bluegrass sod require 50 to 100 Irrigation is necessary in many pounds per acre more fertilizer than the amount necessary for western orchards. Supplemental cultivated trees. irrigation is beneficial in areas with sufficient total rainfall but with inadequate moisture dur- Intercrops ing part of the growing season. An orchard may endure an in- Usually rill, check, or under-the- terplanted crop without appreci- tree sprinkler systems are used. able ill effect, but the crop will Overhead (over-the-tree) sprink- be of no benefit to the trees unless ler systems are in experimental the orchard is given better tillage use in the Pacific Northwest. because of it. Beans, peas, and These can be adapted also to other vegetables of like cultural sprinkling for frost control and requirements are the most com- reduction of leaf and fruit tem- patible. Avoid tomatoes, potatoes, peratures on excessively hot days and other crops susceptible to and to applications of certain verticillium wilt. Crops requiring pesticides, growth regulators, or late-summer cultivation should foliar fertilizers. The hazard of not be used in the Northern increased diseases has not been States, where winter injury of serious and it has been out- cherry is common because of im- weighed by labor-saving advan- maturity of the wood. Pesticides tages such as movement and stor- and timing of sprays for the two age of irrigation pipes. However, crops usually are not compatible. overhead systems should not be The planting of an annual crop installed until their feasibility in an orchard is a system of has been established experiment- double cropping in which the more ally in the grower's immediate important crop is the cherry. The area. tops require only a small part of Sour cherry trees are suscept- the space above ground, but the ible to "wet feet" and should not roots occupy a larger volume of be overirrigated. The need for ir- the soil. Usually it is better to rigation can be predicted reason- plant "filler" trees, preferably ably well from (1) an évapotrans- other sour cherries, than row piration chart for the specific crops, but these must be removed area, (2) moisture tension blocks GROWING SOUR CHERRIES 19 at different depths, or (3) a soil- idly than others, the leader and crumbling test. In the last method the weaker scaffold branches will a ball of soil from the 3-foot depth be choked out (fig. 13). More that is squeezed and jarred slight- pruning than necessary, however, ly will crumble easily if irriga- will delay bearing and dwarf the tion is necessary. On the other tree. Constraint to the minimum hand, trees should not be permit- pruning that will give a balanced, ted to suffer from moisture stress, strong tree will give returns in which may reduce fruit size and precocious bearing. restrict vegetative growth. Mature sour cherry trees re- quire little pruning except re- moval of weak branches, espe- Pruning cially on the inside of the trees (fig. 14). If this is not done they One year after planting, little become brushy, hard to spray and pruning of a sour cherry tree pick, and bear many small un- should be necessary. At this time evenly ripening fruits (fig. 15). It remove extra scaffold limbs left at is best to head back the branches planting time. The more vigorous of trees that become too tall for scaffold limbs may be suppressed convenient harvesting. Moder- by (1) removing some of the ately light pruning accompanied lateral branches and (2) pruning by adequate nitrogen fertilization back the main one to an outward- helps maintain good terminal and upward-branching lateral. growth and vigorous spurs. After a tree has been in the orchard for 2 years, cut back its leader to a strong outward and Thinning Fruit upward lateral arising about 5 feet from the ground. Then select Thinning of fruit usually is two or three additional scaffold not practical for sour cherries. limbs on the upper part of the This is accomplished to some ex- trunk, so that about six, which tent, however, by selective prun- are well distributed along about ing. Thinning out some of the 3 feet of the trunk, finally remain. fruiting wood during the dormant Pruning during the first 4 or 5 season reduces the total number years is mainly to train the young of fruit buds and gives larger trees so as to obtain maximum fruits. However, care should be strength and productivity. Some taken to avoid reducing the over- pruning is necessary each year all production of the orchard. to maintain a balance between the No chemical has been consist- scaffold limbs. If some scaffolds ently effective in thinning sour are allowed to develop more rap- cherries. 20 AGRICULTURE HANDBOOK 451, U.S. DEPT. OF AGRICULTURE

^

PN-29B8 FIGURE 13.—Three-year-old 'Montmorency' cherry tree with weak crotch that resulted from allowing the scaffold branches to crowd out the leader.

HARVESTING Sour cherries usually are har- picker's body. Temporary picking vested without stems. Until about crews estimated at 45,000 workers 1964 the fruit was harvested by were required to harvest the hand into pails harnessed to the Michigan crop alone (58, 81). GROWING SOUR CHERRIES 21

PN-2959 FIGURE 14.—Vigorous 'Montmorency' cherry tree, about 7 years old, received little pruning after selection of scaflfold branches. When the tree was photographed, only a light thinning out of weak limbs in the center was needed. Note the strong, well-spaced scaflfold branches. Many of them were transients, 70 percent, respectively, of the who become more scarce each Michigan crop was harvested by year. The grower has been forced machine (7). In 1970, 600 har- to harvest the crop mechanically. vesting machines were used in In 1964,1967, and 1968, 3, 50, and Michigan (7); in 1971, about 85 22 AGRICULTURE HANDBOOK 451, U.S. DEPT. OF AGRICULTURE

PN-2960 FIGURE 15.—Twelve-jrear-old 'Montmorency' cherry tree that had not been pruned for 5 years and had received very little pruning before that. When photo- graphed, it was too brushy for uniform ripening of high-quality cherries, for thorough spraying, or for easy harvesting of the fruit. All that it needed, however, was some thinning of weak limbs in the center. Note the strong, well-spaced scaffold branches. percent of the crop was harvested in a short time. The cherries are by over 700 machines. cooled to under 60° F. and remain Reciprocating limb or trunk in the pallet tanks until they are shakers are used to shake the pitted 6 to 8 hours later. Trans- fruit onto self-propelled or trac- portation and storage in these tor-drawn catching frames. Most tanks minimize bruising and en- advanced harvesters are operated hance refirming of bruised fruits by two men (fig. 16). The frames {5, 56). are inclined to roll the fruit onto Water sprays are sometimes ap- conveyor belts and then into pallet plied to the trees by airblast ma- tanks of cold water (62). The chines 20 to 30 minutes before tanks are moved within 30 min- harvest to reduce fruit tempera- utes to cooling stations in the ture at least 10° F. (26). Scald, orchard where ice is added. This browning of bruised areas, and removes field heat from the fruits other sources of loss of quality GROWING SOUR CHERRIES 23 ^^^^H L

' ^.'.-Vr. A-'' '■- ■ "A' rti " ' .■^•" > •■ ^•>'^ ' . •••'•'■,■.•• -1

"■ \ ^¿ä£SJ«*~^^-~.,^:>i^^KBÊt^^>^'^:'^^am^mÊ^^K& Wk 1 El--*: "^^^^-^ '^Jj^- i% ¡^ ■? " . f ■ '-•ik'

PN-2961 FIGURE 16.—Machine harvesting sour cherries in Michigan orchard. and subsequent reduction in pack- acid (ethephon) and suc- out are minimized by such treat- cinic acid 2,2-dimethylhydrazide ment {B6). (SADH), reduce the force neces- A single mechanical harvester sary to remove fruits from the and its crew remove at least as tree (2, 10, 11, 18, 29, 30, 59, 83) much fruit as 33 handpickers and thereby may reduce bruising. {58). The newest machines with Sprays of the latter chemical 2 two men harvest over 60 trees per weeks after full bloom enhanced hour. Cost per pound of fruit re- anthocyanin development and al- moved by mechanical harvesters tered ceil wall composition of is comparable to, and often less 'Montmorency' fruits {23, 83). than, that of handpicking. Michi- Treated fruits had more total an- gan researchers estimate that har- thocyanins and more pectin and vesting fruit from 15 acres of hemicellulose, and they were sour cherry trees makes one unit firmer. economical {81). Cherries har- In 1970, 60 percent of Michi- vested and handled by machinery gan cherries were sold by volume are bruised less than those hand- rather than by weight (75). Fruit picked (7, 12, 72). Certain ex- scald was reduced by elimination perimental chemical sprays, of the rehandling formerly associ- notably 2-chloroethylphosphonic ated with weighing the fruit. 24 AGRICULTURE HANDBOOK 451, U.S. DEPT. OF AGRICULTURE

Thus the cherries are handled in and high harvesting labor costs water tanks until they reach the have encouraged pick-your-own- processing plant, where they go fruit operations. Orchards near over a machine that removes population centers often attract stems, usually on 1 to 10 percent families interested in picking of the fruits, and then are con- fruit for their own use or in buy- veyed to the pitter. ing tree-ripened fruit from road- The shortage of trained pickers side markets.

PACKING Some sour cherries are sold for boxes. These are packed into 16- fresh consumption (6^). Several or 24-quart crates for marketing. methods are used to pack cherries Also used are the western lug, for the fresh-fruit market. holding 15 to 20 pounds, and the Fruit is occasionally packed di- 4-quart climax basket. rectly into baskets of various sizes. Sometimes the picking pails For highest quality and least are emptied onto a sorting table spoilage, cherries for fresh con- or conveyor, from which the cher- sumption must be handled with ries are transferred to 1-quart stems attached and kept cool (57).

PROCESSING Processing details are not in- is referred to a few pertinent pub- cluded in this handbook. However, lications on processing (6, 25, 61, since about 95 percent of the sour 69, 75, 76, 80, Sind 85). cherries are processed, the reader

VIRUS DISEASES Several virus diseases affect duces symptoms only during the cherries in the north-central and initial stages of infection, which northeastern areas of the United usually last 1 to 2 years. After States (82). this, infected trees may show no symptoms except varying degrees Ringspot of retarded growth, yet they stand The stone fruit ringspot virus as virus reservoirs from which is widespread in commercial stone further spread can occur. fruit orchards throughout North During the early stages of in- America, but few trees show fection, foliation is retarded and symptoms. On sour cherry it in- sparse. As the season advances, ' Prepared by L. C. Cochran. leaves fail to size and many bear GROWING SOUR CHERRIES 25 ring and necrotic patterns. The delay further spread is probably patterns become progressively ne- no longer practical. Diseased crotic and some areas drop out trees produce less and poorer giving some leaves a shot-holed quality fruits, but they are still and tattered appearance (87), salable. Leaf symptoms are accompanied by necrosis of leaf and flower buds Sour Cherry Yellows and few fruits are set on affected The disease known as yellows parts. is widespread in sour cherry The ringspot virus is seedborne orchards. One-third of the trees in stone fruits and infects a high in commercial orchards in the percentage of the seeds of sour United States are infected. The cherries. It also infects pollen disease is caused by a combina- and is carried from diseased to tion of the Prunus ringspot vi- healthy trees in pollen. Some of rus and the agent that induces the infected pollen grains fertilize prune dwarf in P. domestica the ovules and result in infected plums. There is evidence that the seed, and some invade the ovary latter is a mycoplasma and not a tissues where they discharge virus. virus. This virus then is trans- The ñrst symptoms of yellows— located from the young fruits green and yellow mottling of into the previously healthy tree. the older leaves—appear in early Prevention is the best control. summer, 3 to 4 weeks after petal There is no cure once a tree is fall. These leaves usually drop infected. Budwood can be freed promptly and periodic waves of of the Prunus ringspot virus by leaf fall follow. Symptoms are exposure to dry heat at 100° F. most pronounced on trees in the for 4 to 5 weeks. This budwood better producing areas that have can then be used to establish cool summers, such as those foundation stocks, which in turn bordering the Great Lakes. Symp- are used by nurserymen to pro- toms may not be expressed on duce ringspot-free nursery stock. diseased trees in the warmer Seed for rootstocks must also areas of the Midwest. come from ringspot-free trees When trees have been affected grown in isolated areas where by yellows for several years, they they cannot be pollinized by dis- develop abnormally large leaves eased pollen. Do not plant young and produce few fruit spurs. The orchards of ringspot-free trees shoots that should have become near old, infected orchards. spurs lengthen, become pendant, Promptly remove newly infected and give the tree a weeping ap- trees in young orchards. When pearance. Affected trees bear 10 percent or more of the trees small crops of large fruits. There have become infected, roguing to is no cure for infected trees, but 26 AGRICULTURE HANDBOOK 451, U.S. DEPT. OF AGRICULTURE

more spurs and greener leaves trees, particularly those on maz- have resulted from experimental zard rootstock, as soon as they gibberellin treatments (65). can be recognized. X-disease also Yellows is spread by infected affects sweet cherries and the en- pollen and seed in the same way tity moves from them to sour as Prunus ringspot. The control cherries. Where possible, do not is similar to that for ringspot. plant new orchards near old Several nurserymen can now sup- sweet or sour cherry orchards. ply yellows-free sour cherry nurs- In areas where this disease ery trees. spreads rapidly and orchard iso- lation is not possible, some con- trol has been obtained by top- X-Disease working scions on the individual X-diseased sour cherry trees scaffold arms of mahaleb frame- have sparse, light-green foliage work trees. Since the causal and fail to mature their fruits. agent does not pass from one arm At normal maturity time, af- through the mahaleb interstock, fected fruits remain small and the agent can be eradicated by pink. Affected trees die back removing the diseased arm just over several years. Recent evi- below the graft union. The so- dence indicates that X-disease is called "Russian" or "Turkish" caused by mycoplasma and is not mahaleb cherries are more vigor- a virus disease (43). ous and cold hardy than the com- In the Eastern United States mon clones. the X-disease agent moves direct- ly from diseased choke cherries Pink Fruit (P. virginiana L.) to unaffected cherries. It can be controlled by The pink fruit disease is lim- removing the choke cherries from ited to a small area on the west within 500 feet of the orchard. side of the Cascade Mountains In the Western United States the near Tacoma, Wash. It is a dev- agent is spread by leafhoppers, astating disease but has shown which feed and breed on cherries no indication of rapid spread. as well as on choke cherries. Up to 50 percent of the fruits Trees on mahaleb cherry root- on affected trees fail to mature stock tend to die rapidly and are and remain a salmon pink color poorer reservoirs of infection at normal harvesttime. The vas- than are trees on mazzard root- cular tissue in affected fruits be- stock. To control X-disease in the comes necrotic and turns rusty Western United States, it is nec- brown. The disease is distin- essary to remove not only choke guished from X-disease by fail- cherries from the vicinity of the ure of transmission to peach and orchard but also diseased cherry by the random occurrence of dis- GROWING SOUR CHERRIES 27 eased and unaffected fruits Other Virus Diseases throughout affected trees. Where Several other virus and virus- affected trees have been promptly like diseases occasionally affect rogued, the disease has disap- sour cherries but as yet are not peared. considered serious.

FUNGUS DISEASES' The most important fungus dis- tion to adjacent leaves and trees. eases of cherry are leaf spot (fig. If not controlled, leaf spot 17) and brown rot of the fruit. causes partial to complete defolia- tion U9, 50). In mild cases only a small number of leaves may be spotted, but frequently during damp or rainy weather the spots become so numerous that the tree is completely defoliated be- fore the crop is harvested (fig. 18). Control of leaf spot on sour cherries may require as many as five spray applications: (1) As soon as the petals have fallen, (2) when about three-fourths of the shucks have dropped, (3) PN-2962 about 10 days after the second FIGURE 17.—Sour cherry leaves affected spray, (4) 10 days to 2 weeks by leaf spot. after the third spray, and (5) immediately after harvest. Leaf Spot Growers should consult their Leaf spot is caused by a fungus State agricultural experiment sta- (Coccomyces hiemalis Higgins) tion or county agricultural agent that overwinters on fallen leaves. for information regarding the In the spring the spores are dis- fungicides best suited to their charged from these leaves and localities and the timing of carried by the wind to the new sprays. Use only materials and leaves, where they germinate and rates currently registered for cause infection. Small spots, pur- your area. plish at first but finally brown, Certain materials that have develop on the leaves and pro- been used to control leaf spot oc- duce enormous numbers of sum- casionally cause damage. Liquid mer spores. These spread infec- lime-sulfur may discolor the fruit. ' Prepared by H. L. Keil. Bordeaux mixture may reduce the 28 AGRICULTURE HANDBOOK 451, U.S. DEPT. OF AGRICULTURE

n lo

OTHER DISEASES Other fungus diseases, such as powdery mildew (Podosphaera black knot (Dibotryon mor- oxyacanthae (DC) d By.), leaf bosum (Schw.) Th. & Syd.), rust (Tranzschelia pruni-spinosae GROWING SOUR CHERRIES 29

(Pers.) Diet.), wilt (Verticillium Most of them are held in check albo-atrum Reinke & Berth.), by applying sprays used to con- and scab (Cladospoñum carpo- trol leaf spot and brown rot. philum Thuem.), occur to some A bacterial leaf spot caused by extent on sour cherries. These dis- Xanthomonas pruni (E. F. Sm.) eases are usually less serious than Dows. sometimes aifects 'Mor- either leaf spot or brown rot. ello' cherries {27).

INSECTS

The insect pests most commonly trees bloom, the curculios move found on cherry trees are the to the trees. Females insert their black cherry aphid, the plum eggs just beneath the skin of the curculio, two kinds of fruit flies, cherries. They then make and the pearslug. crescent-shaped slits, each of

Black Cherry Aphid The black cherry aphid (My- zus cerasi (F.)) is a tiny, black, shiny insect that curls the tender young foliage of the cherry early in the season (fig. 19). Often it severely checks growth. It rarely injures the sour cherry seriously. The insects overwinter as tiny, black eggs on twigs and small branches. The eggs hatch in the spring about the time the tree growth starts, and the young aphids cluster on opening buds.

Plum Curculio The plum curculio (Conotra- chelus nenuphar (Herbst)) is a humpedback, brown beetle that hibernates in trash in the orch- ard or near it. Early in the spring, soon after the cherry

' Prepared by Merrill L. Cleveland, PN-2964 staff scientist, National Program Staff, FIGURE 19.—Cherry leaves curled by the Agricultural Research Service. cherry aphid. 30 AGRICULTURE HANDBOOK 451, U.S. DEPT. OF AGRICULTURE

which partly surrounds an egg the fruit to be misshapen and puncture (fig. 20). The curculio often prematurely colored. larvae, or grubs, feed within the cherries for several weeks. Pearslug The pearslug, also called the Fruit Flies cherryslug (Caliroa cerasi L.), is a slimy, dark worm that feeds In the Northern States, cher- on cherry leaves. The slugs ap- ries are sometimes infested by pear on the trees in May or maggots of two species of fruit June depending on the locality. flies {Rhugoletis cingulata A second brood may appear in (Loew) and R. fausta (Osten midsummer or late summer. Sacken)) (36). These species have yellowish heads and legs More information about these and are distinguished by con- and other insects attacking cher- spicuous bands across the wings ries is available in Home and and distinct white crossbands on Garden Bulletin 190, "Insects on the abdomen of the R. cingulata. Deciduous Fruits and Tree Nuts Adult flies, about two-thirds the in the Home Orchard," which size of house flies, appear just may be purchased from the Su- after the blossom buds open. The perintendent of Documents, U.S. females lay eggs in the fruit Government Printing Office, when it appears. Maggots cause Washington, D.C. 20402.

PN-2966 FIGURE 20.—Puncture marks made by plum curculios inserting eggs into cherry- fruits. GROWING SOUR CHERRIES 31

For information on insecticides Since some States have restric- to be used, dosages, and timing of y^^^^ ^^ ^^^ ^^^ ^f ^^^ain pest- applications, consult your county agricultural agent or State ag- ^^^^^^> ^^^^^^ ^^"^ State and local ricultural experiment station, regulations.

LITERATURE CITED

(1) ANONYMOUS. 1963. LITERATURE SURVEY OF FRUIT TREE ROOTSTOCKS. 83 pp. Gerber Prod. Co., Fremont, Mich. [Processed.] (2) ANDERSON, J. L. 1969. THE EFFECT OF ETHREL ON THE RIPENING OF MONTMORENCY SOUR CHERRIES. HortScience 4: 92-93. (3) ANDERSON, L. C. 1935. A SURVEY OF THE BEHAVIOR OF CHERRY TREES IN HUDSON RIVER VALLEY WITH PARTICULAR REFERENCES TO LOSSES FROM WINTER KILLING AND OTHER CAUSES. N.Y. Agr. Expt. Sta. Bui. 653, 23 pp. (4) ANTHONY, R. D., SUDDS, R. H., and YERKAS, G. E. 1938. ORCHARD TESTS OF MAZZARD AND MAHALEB CHERRY UNDERSTOCKS. Amer. Soc. Hort. Sei. Proc. 35: 415-418. (5) ARNOLD, C. E., and MITCHELL, A. E. 1970. HISTOLOGY OF BLEMISHES OF CHERRY FRUITS (PRUNUS CERASUS L. CV. MONTMORENCY) RESULTING FROM MECHANICAL HARVESTING. Amer. Soc. Hort. Sei. Jour. 95: 723-725. (6) BEDFORD, C. L., and ROBERTSON, W. F. 1962. PROCESSED MONTMORENCY CHERRIES—A TEN YEAR SUMMARY. Mich. Agr. Expt. Sta. Quart. Bui. 45: 334-344. (7) BOLEN, J. S., and CARGILL, B. F. 1970. MECHANIZED HARVEST SYSTEMS. Mich. Agr. Expt. Sta. Bui. E-660, 6 pp. (8) BRASE, K. D., and WAY, R. D. 1959. ROOTSTOCKS AND METHODS USED FOR DWARFING FRUIT TREES. N.Y. Agr. Expt. Sta. Bui. 783, 30 pp. (9) BROOKS, R. M., and OLMO, H. P. 1972. REGISTER OF NEW FRUIT AND NUT VARIETIES. Ed. 2, 708 pp. Univ. Calif. Press, Berkeley. (Includes lists 1-25; lists 26, 27, and 28 in HortScience 6: 439-442, 7: 455-460, and 8: 378-383.) (10) BUKOVAC, M. J. 1971. THE NATURE AND CHEMICAL PROMOTION OF ABSCISSION IN MATURING CHERRY FRUIT. HortScience 6: 385-388. (11) ZuccoNi, F., LARSEN, R. P., and KESNER, C. D. 1969. CHEMICAL PROMOTION OF FRUIT ABSCISSION IN CHERRIES AND PLUMS WITH SPECIAL REFERENCE TO 2-CHLOROETHYLPHOSPHONIC ACID. Amer. Soc. Hort. Sei. Jour. 94: 226-230. (12) CAIN,J. C. 1967. THE RELATION OF FRUIT REMOVAL FORCE TO THE MECHANICAL HARVEST- ING EFFICIENCY OF MONTMORENCY CHERRY. HortScience 2: 53-55. (13) CARLSON, R. F. 1969. MONTMORENCY CHERRY SELECTIONS. Mich. Agr. Expt. Sta. Res. Rpt. 101: 3-4. 32 AGRICULTURE HANDBOOK 451, U.S. DEPT. OF AGRICULTURE

(14) CLARKE, W. S., and ANTHONY, R. D. 1964. AN ORCHARD TEST OF MAZZARD AND MAHALEB CHERRY ROOTSTOCKS. Amer. Soc. Hort. Sei. Proc. 48: 200-208. (15) COE, F. M. 1945. CHERRY ROOTSTOCKS. Utah Agr. Expt. Sta. Bul. 319, 43 pp. (16) CRANE, M. B., and LAWRENCE, W. J. C. 1934. THE GENETICS OF GARDEN PLANTS. 236 pp. MacMillan & Co., Ltd., London. (17) CRIST,J.W. 1939. PHOTOSYNTHETIC STUDIES OF NUTRITIONAL BARRENNESS IN THE MONT- MORENCY CHERRY. Jour. Agr. Res. 59: 547-554. (18) CROCKER, T. F., and KENWORTHY, A. L. 1970. EFFECTS OF N, K, AND ALAR ON VEGETATIVE GROWTH, YIELD AND QUALITY OF SOUR CHERRY, PRUNUS CERASUS CV. MONTMORENCY. (Abstract) HortScience 5: 326. (19) CULLINAN, F. P. 1937. IMPROVEMENT OF STONE FRUITS: CHERRIES. U.S. Dept. Agr. Ybk. 1937: 724-737. (20) CURWEN, D., MCARDLE, F. J., and RITTER, C. M. 1966. FRUIT FIRMNESS AND PECTIC COMPOSITION OF MONTMORENCY CHERRIES AS INFLUENCED BY DIFFERENTIAL NITROGEN, PHOSPHORUS AND POTAS- SIUM APPLICATIONS. Amer. Soc. Hort. Sei. Proc. 89: 72-79. (21) DAY,L.H. 1951. CHERRY ROOTSTOCKS IN CALIFORNIA. Calif. Agr. Expt. Sta. Bul. 725, 31 pp. (22) DE CANDOLLE, A. 1890. ORIGIN OF CULTIVATED PLANTS. 207 pp. Appleton Inc., New York. (23) DEKAZOS, E. D., and WORLEY, J. F. 1970. EFFECT OF SUCCINIC ACID 2,2-DIMETHYL HYDRAZIDE ON ANTHOCYANIN METABOLISM AND CELL WALL CARBOHYDRATES IN RED TART CHERRIES. Amer. Soc. Hort. Sei. Jour. 95: 703-706. (24) DENNIS, C. C. 1963. LONG-RUN EQUILIBRIUM IN TART CHERRY PRODUCTION. Mich. Agr. Expt. sta. Tech. Bui. 291, 32 pp. (25) DoMiNicK, B. A., and KELLY, B. W. 1964. THE GREAT LAKES TART CHERRY INDUSTRY: PRODUCTION COSTS. U.S. Dept. Agr. Econ. Res. Serv. Rpt. 171, 24 pp. (26) DIENER, R. G., WHITTENBERGER, R. T., and LEVIN, J. H. 1968. PREHARVEST SPRAY COOLING FOR TART CHERRIES. Mich. Agr. Expt. Sta. Res. Rpt. 69, 4 pp. (27) DUNEGAN, J. C. 1935. A DISEASE OF THE ENGLISH MORELLO CHERRY CAUSED BY BACTERIUM PRUNI. Jour. Agr. Res. 49: 745-754. (28) EDGERTON, L. J. 1950. CHERRY GROWING IN NEW YORK. N.Y. Agr. Expt. sta. Ext. Bui. 787, 24 pp. 129) 1968. NEW MATERIALS TO LOSSEN FRUIT FOR MECHANICAL HARVESTING. N.Y. State Hort. Soc. Proc. 113: 99-102. GROWING SOUR CHERRIES 33

(30) and HATCH, A. H. 1969. PROMOTING ABSCISSION OF CHERRIES AND APPLES FOR MECHANICAL HARVESTING. N.Y. State Hort. Soc. Proc. 114: 109-113. (31) EiNSET, 0. 1932. EXPERIMENTS IN CHERRY POLLINATION. N.Y. Agr. Expt. Sta. Bul. 617, 13 pp. (32) FOGLE, H. W. 1965. PROGRESS AND PROBLEMS IN TREE FRUIT AND NUT PRODUCTION: STONE FRUITS. Advn. in Agron. 17: 295-312. (33) HANSON, K. W., PETERSON, R. M., and others. 1961. SOURCES OF PROPAGATION WOOD FOR CHERRY VARIETIES AND SPECIES IN THE UNITED STATES AND CANADA. Fruit Varieties and Hort. Digest 16: 2-11. (34) FRENCH, A. P. 1943. PLANT CHARACTERS OF CHERRY VARIETIES. Mass. Agr. Expt. Sta. Bul. 401, 23 pp. (35) FRENCH, B. C. 1957. TRENDS AND CHARACTERISTICS OF RED CHERRY CONSUMPTION. Mich. Agr. Expt. Sta. Spec. Bul. 414, 32 pp. (36) FRICK, K. E., SIMKOVER, H. G., and TELFORD, H. S. 1954. BIONOMICS OF THE CHERRY FRUIT FLIES IN EASTERN WASHINGTON. Wash. Agr. Expt. Sta. Tech. Bul. 13, 66 pp. (37) GARDNER, V. R. 1935. THE SUSCEPTIBILITY OF FLOWER BUDS OF THE MONTMORENCY CHERRY TO INJURY FROM LOW TEMPERATURE. Jour. Agr. Res. 50: 563-572. (38) 1936. FACTORS INFLUENCING THE YIELDS OF MONTMORENCY CHERRY ORCHARDS IN MICHIGAN. Mich. Agr. Expt. sta. Spec. Bul. 275, 18 pp. (39) 1943. STUDIES IN THE NATURE OF THE CLONAL VARIETY. III. PERMANENCE OF STRAIN AND OTHER DIFFERENCES IN THE MONTMORENCY CHERRY. Mich. Agr. Expt. Sta. Tech. Bul. 186, 20 pp. (40) 1946. THE CHERRY AND ITS CULTURE. 146 pp. Orange Judd Pub. Co., New York. (Rev.) (41) and TOENJES, W. 1948. STRAIN DIFFERENCES IN THE MONTMORENCY CHERRY. Mich. Agr. Expt. Sta. Quart. Bul. 31: 83-90. (42) GLOYER, W. 0., and GLASGOW, H. 1928. DEFOLIATION OF CHERRY TREES IN RELATION TO WINTER INJURY. N.Y. Agr. Expt. sta. Bul. 555, 27 pp. (43) GRANETT, A. L., and GILMER, R. M. 1971. MYCOPLASMAS ASSOCIATED WITH X-DISEASE IN VARIOUS PRUNUS SPECIES. Phytopathology 61: 1036-1037. (44) GRAY, G. F. 1934. RELATION OF LIGHT INTENSITY TO FRUIT SETTING IN THE SOUR CHERRY. Mich. Agr. Expt. Sta. Tech. Bul. 136, 35 pp. (45) GRUBB, N. H. 1933. CHERRY STOCKS AT EAST MALLING: I. STOCKS FOR MORELLO CHERRIES. Pomol, and Hort. Sei. Jour. 11: 276-304. 34 AGRICULTURE HANDBOOK 451, U.S. DEPT. OF AGRICULTURE

(46) HASKELL, G. 1954. STAMEN NUMBER AND VARIATION IN DIPLOID AND TETRAPLOID CHERRIES. Ann. Bot. 18: 95-111. (47) HEDRICK, U. P. 1914. THE CHERRIES OF NEW YORK. N.Y. AgT. Expt. Sta. Ann. Rpt. 22 (2) : 1-371. (48) HOWE, G. H. 1927. MAZZARD AND MAHALEB ROOTSTOCKS FOR CHERRIES. N.Y. AgT, Expt. Sta. Bui. 544,13 pp. (49) KEIL,H. L. 1965. CHERRY LEAF SPOT AND ITS CONTROL. U.S. Dept. AgT. Leaflet 489, 6 pp. (50) KEITT, G. W., BLODGETT, E. C, WILSON, E. E., and MAGIE, R. 0. 1937. THE EPIDEMIOLOGY AND CONTROL OF CHERRY LEAF SPOT. Wis. AgT, Expt. Sta. Res. Bui. 132,117 pp. (51) KENWORTHY, A. L. 1954. EFFECTS OF SODS, MULCHES, AND FERTILIZERS IN A CHERRY ORCHARD ON PRODUCTION, SOLUBLE SOLIDS, AND ON LEAF AND SOIL ANALYSES. MICH. AgT. Expt. Sta. Tech. Bui. 243, 39 pp. (52) and MITCHELL, A. E. 1952. SOLUBLE SOLIDS IN MONTMORENCY CHERRIES AT HARVEST AS INFLU- ENCED BY SOIL MANAGEMENT PRACTICES. Amer. Soc. Hort. Sci. Proc. 60: 91-96. (53) KESNER, C. C. 1969. IRRIGATION FOR CHERRIES IN NORTHWESTERN MICHIGAN. Mich. AgT. Expt. Sta. Res. Rpt. 101: 5-6. (54) KLOS, E. J., and FRONEK, F. R. 1964. CHEMICAL ERADICATION OF CHERRY LEAF SPOT FUNGUS. Mich. AgT. Expt. sta. Quart. Bui. 47: 65-68. (55) KNIERIM, J. A. 1964. A SOIL FUMIGATION TEST IN RELATION TO THE CHERRY REPLANT PROB- LEM. Mich. Agr. Expt. Sta. Quart. Bui. 46: 527-532. (56) LA BELLE, R. L., WOODAMS, E. E., and BOURNE, M. C. 1964. RECOVERY OF MONTMORENCY CHERRIES FROM REPEATED BRUISING. Amer. Soc. Hort. Sei. Proc. 84: 103-109. (57) LEVIN, J. H., and GASTON, H. P. 1956. GROWER HANDLING OF RED CHERRIES. Mich. Agr. Expt. Sta. Cir. 981, 20 pp. (58) GASTON, H. P., HEDDEN, S. L., and WHITTENBERGER, R. T. 1960. MECHANIZING THE HARVEST OF RED TART CHERRIES. Mich. Agr. Expt. Sta. Quart. Bui. 42: 1-32. (59) LOONEY, N. E., and MCMEEHAN, A. D. 1970. THE USE OF 2-CHLOROETHYLPHOSPHONIC ACID AND SUCCINAMIC ACID 2,2-DIMETHYLHYDRAZIDE TO AID IN MECHANICAL SHAKING OF SOUR CHERRIES. Amer. Soc. Hort. Sei. Jour. 95: 452-455. (60) MCMANUS, G. A., and KENWORTHY, A. L. 1953. PREVENTION OF POTASSIUM DEFICIENCY IN MONTMORENCY CHERRY TREES WITH POTASSIUM SOLUTIONS APPLIED AT PLANTING TIME. Mich. Agr. Expt. Sta. Quart. Bui. 36: 11-12. GROWING SOUR CHERRIES 35

(61) MARSHALL, R. E. 1954. CHERRIES AND CHERRY PRODUCTS. 283 pp. Interscience Pub., New York. (62) MousTAFA, S., FARMER, D. M., and HANSEN, C. M. 1968. HYDROHANDLING OF CHERRIES. Mich. Agr. Expt. Sta. Res. Rpt. 74, 8 pp. (63) OLDEN, E. J., and NYBOM, N. 1968. ON THE ORIGIN OF PRUNUS CERASUS L. Hereditas 59: 327-345. (64) OLDENSTADT, D. L. 1964. ECONOMIC RELATIONSHIPS IN RED TART CHERRY MARKETING, 1947-63. Mich. Agr. Expt. Sta. Econ. Mimeo. 971, 50 pp. (65) PARKER, K. G., EDGERTON, L. J., and HICKEY, K. D. 1964. GIBBERELLIN TREATMENT FOR YELLOWS-INFECTED SOUR CHERRY TREES. Farm Res. (N.Y. Agr. Expt. Sta.) 29: 8-9. (66) POWELL, G. H. 1900. THE SOUR CHERRIES OF AMERICA. Del. Agr. Expt. Sta. Ann. Rpt. 12 : 99-128. (67) PROEBSTING, E. L., JR., and KENWORTHY, A. L. 1954. GROWTH AND LEAF ANALYSIS OF MONTMORENCY CHERRY TREES AS IN- FLUENCED BY SOLAR RADIATION AND INTENSITY OF NUTRITION. Amer. Soc. Hort. Sei. Proc. 63: 41-48. (68) RUEF,J. U. 1936. CHERRY PRODUCTION IN PENNSYLVANIA. Pa. Agr. Expt. Sta. Cir. 172, 8 pp. (69) SHIEH, J. T., and DENNIS, C. C. 1965. THE TART CHERRY INDUSTRY: PROCESSING COSTS AND EFFICIENCY. Mich. Agr. Expt. Sta. Res. Rpt. 27, 36 pp. (70) SIMONS, R. K., and CARLSON, R. F. 1968. CHARACTERISTICS AND PROPAGATION OF ROOTSTOCKS FOR DECIDUOUS FRUITS IN THE NORTH CENTRAL REGION 1966-67. HortScience 3: 221-225. (71) SMEETS, L. 1957. SOME EFFECTS OF THE PHOTOPERIOD ON THE SHOOT GROWTH OF CHERRY SEEDUNGS. Euphytica 5: 238-244. (72) STOSSER, R., RASMUSSEN, H. P., and BUKOVAC, M. J. 1969. HISTOCHEMICAL CHANGES IN THE DEVELOPING ABSCISSION LAYER IN FRUITS OF PRUNUS CERASUS L. Planta 86: 151-164. (73) SwANSON, J. p., GARRETT, J. R., and ZUROSKE, C. H. 1965. GROWER ESTIMATES OF PRODUCTION COSTS; CHERRIES, PEACHES, PEARS AND PLUMS, YAKIMA VALLEY, 1962 AND 1963. Wash. Agr. Expt. Sta. Cir. 452, 28 pp. (74) SWINGLE, C. F. 1951. CHERRY GROWING IN DOOR COUNTY, WISCONSIN. 17 pp. Sturgeon Bay, Wis. [Processed.] (75) TENNES, B. R., ANDERSON, R. L., and LEVIN, J. H. 1968. WEIGHT TO VOLUME RELATIONSHIP OF TART CHERRIES. Mich. Agr. Expt. sta. Res. Rpt. 70, 4 pp. (76) TRISCOLL, J. H., COLLINS, D., and SYER, M. 1962. CANNED MONTMORENCY CHERRY PIE FILLING. Hort. Expt. Sta. and Prod. Lab. Rpt. 1962, pp. 129-131. 36 AGRICULTURE HANDBOOK 451, U.S. DEPT. OP AGRICULTURE

(77) TUKEY, H. B. 1927. RESPONSES OP THE SOUR CHERRY TO PERTILIZERS ANÖ TO PRUNING IN THE HUDSON RIVER VALLEY. N.Y. AgT. Expt. Sta. Bul. 541, 26 pp. (78) and BRASE, K. D. 1934. RANDOM NOTES ON FRUIT TREE ROOTSTOCKS AND PLANT PROPAGATION. N.Y. Agr. Expt. Sta. Bul. 649, 22 pp. (79) TuKEY, L. D. 1961. A REVIEW OF THE CHERRY SITUATION WITH PROJECTED DEMANDS TO 1975. PT. Ill, THE SOUR CHERRY SITUATION. Agindus. Adjust. Conf. Proc. 1961, pp. 13-31. (80) TwsEATL, J. H., and NORSWORTHY, M. 1967. FREEZING MONTMORENCY CHERRIES. Ontario Hort. Res. Inst. Rpt. 1967, pp. 73-99. (81) UNITED STATES DEPARTMENT OF AGRICULTURE. 1964. MECHANIZING THE HARVESTING AND ORCHARD HANDLING OF FRUITS. U.S. Dept. Agr. ARS Spec. Rpt. 22-88,16 pp. (82) 1951. VIRUS DISEASES AND OTHER DISORDERS WITH VIRUSLIKB SYMPTOMS OF STONE FRUITS IN NORTH AMERICA. U.S. Dept. AgT. Agr. Handb. 10, 276 pp. (83) UNRATH, C. R., KENWORTHY, A. L., and BEDFORD, C. L. 1969. THE EFFECT OF ALAR, SUCCINIC ACID 2,2-DIMETHYLHYDRAZn)E, ON PRtHT MATURATION, QUALITY AND VEGETATIVE GROWTH OF SOUR CHERRIES PRUNUS cERAsus L. cv. MONTMORENCY. Amer. Soc. Hort. Sei. Jour. 94: 387-391. (84) WELLINGTON, R. 1947. POLLINATION OF FRUIT TREES. N.Y. Agr. Expt. Sta. Bul. 720, 8 pp. (85) WHITTENBERGER, R. T., GASTON, H. P., and LEVIN, J. H. [n.d.] EFFECT OF RECURRENT BRUISING ON THE PROCESSING OF RED TART CHERRIES. Mich. Agr. Expt. Sta. Res. Rpt. 4, 6 pp. (86) and HILLS, C. H. 196Q. BRUISING OF RED CHERRIES IN RELATIONSHIP TO THE METHOD OF HARVEST. U.S. Dept. Agr. ARS 73-27,14 pp. (87) WiLLisoN, R. S., BERKELEY, G. H., and CHAMBERLAIN, G. C. 1948. YELLOWS AND NECROTIC RING SPOT OF SOUR CHERRIES IN ONTARIO— DISTRIBUTION AND SPREAD. Phytopathology 38: 776-792.

':4, iirU.S. GOVERNMENT PRINTING OFFICE: 1974 0—505-755