JULY 1980 BULLETIN 519 iC~(i L ~RICUUVL '1C XPERIMENT STATION ABR AUBURN UNIVER NVR CONTENTS PRUNING EXPERIMIENT Page .. . .. ... .. . .. .. .. . .4 Results and Discussion 6 ................. TREE SPACING AND LIMB POSITIONING EXPERIMENT................ 9 10 12 Results and D)iscussion .............................. CONCLUSION ............................................... DISCUSSION AND RECOMMENDATIONS............................ 12 23 LITERATURE CUTED .. ....................................... Mii- PRINTING 4M, JULY 1980 Information contained herein is available to all withot regard to race, color, sex, or national origin. Pruning and Training of Red Delicious Apples W. A. DOZIER, J., C. C. CARLTON, K. C. SHORT, W. A. GRIrFEY, H. E. BURGESS, A. A. POWELL, and JOHN McGUIRE' ilW() MAJ0o PII)larLMS confronting the apple industry are increasing cost of production and a lack of qualified workers, particularly for pruning and harvesting operations (2,3,5). Kelsey (11) reported in 1971 that pruning accounted for over 30 percent of apple production cost. This has probably increased since then, since labor available for pruning has decreased and become more expensive. Smith ald Feree (14) reported that time required tree training accounted for 43 percent of the preharvest lal)or requirements. In an effort to improve pruning efficiency andlreduce cost, research with various mechanical pruners has been conducted by a number of research workers (2,3,5,6,8,9). Even though the use of mechanical cutter bars to hedge and top trees reduces time necessary to prune orchards, such pruning results in a dense periphery of vigorous shoot growth. This dense growth reduces light penetration into the canopy, which results in suppressed spur formation, spur death, and poorly colored, smiall fruit (2,3,5). Mechanical pruning plus supplemental hand pruning has been an effective method (6,9), but the effect of annual mne- for chanical pruning on yield has not been .Mdllirney (12) reported that picking rate by fruit harvesters investigated. decreased by 0.4 bushel per hour for each 1-foot increase in bearing height of the tree. Thus, a picker would harvest 4 bushels per hour less from a 20-foot high tree than from a 10-foot high tree. Gilbert (7) reported that Auvil has successfully grown trees at Rlespectively, Associate Professor, I)e partinent Ilorticultore; Superintendent and Assistant Stiperintendenit, Chilton Area.I lorticulture Suibstation; Sit rriteiident and Serv ice Fruit Assistant Superintendent, IPiedmiont Substation; Cooperative Sp~ecialist; and Associate Professor, I)epartment or Research IData Analysis. of Extension 4 ALABAMA AGRICULTURAL EXPERIMENT STATION close spacing to a 14-foot height and then maintained the trees thereafter at this height by removing all annual terminal growth. lie has produced 2,000 bushels per acre each year using this method, which is known as the "mold and hold" system. Research to determine the effect of pruniig treatments and row spacing on yield and tree performance was initiated by the Auburn University Agricultural Experiment Station at its Chilton Area Horticulture Substation, Clanton, and Piedmont Substation, Camp lill. PRUNING EXPERIMENT The pruning study was established on Vance Red Delicious apples in their ninth leaf on MM106 rootstock. The trees were trained to a modified central leader at a spacing of 15 feet by 20 feet and had formed a solid wall in the row. All trees were hand pruned at the onset of the expeliment. Treatments consisted of (1) mechanical pruning annually, (2) mechanical pruning plus detailed hand pruning annually, (3) hand pruning annually, and (4) mechanical pruning annually plus hand pruning the first, third, and fifth years. Each treatment was replicated four times FIG. 1. A Fossum tree pruner mounted on front of tractor. PRUNING AND TRAINING RED DELICIOUS APPLES 5 in a randomized complete block design with 10 trees per replication. Mechanical pruning was done with a Fossum tree pruner mounted on the front of a tractor, figure 1. The pruner blade was set at an 800 angle so that each side of the tree top was cut at a slant, upward to the center. The blade was positioned so that the vious year's growth was removed. Conventional hand pruning techniques were used to maintain a modified central leader on hand pruned treatments. The time necessary to do both the mechanical and hand pruning was recorded. Tree fruiting height was maintained at 8 feet, conforming to growers' desire to maintain a fruiting height that would allow harvesting without the use of ladders. Light readings were taken in 1974 with a Weston Model 756 sunlight illumination meter in the center of the tree at depths of 1, 2,3, and 4 feet below the canopy surface. Similar readings were taken near the outer periphery of the limb spread. Recommended practices for fertilization and insect, disease, and weed control were followed (4,15). Fruit were thinned with 2 pounds of Sevin per 100 gallons of spray solution 21 days after full bloom, followed by hand spacing and thinning of clusters. pre- I ". .. cal Tis 3 i' ° e. ," t f. ! runr._ esuted FIG.2. Alare nuber E f n athic sootsdeveope .il41 caopywhic nea eac 1s" : prhibied cu mad igh wit . " pentraion th mecani f " 6 - ALABAMA AGRICULTURAL EXPERIMENT STATION FIG. 3. Row of trees on right was mechanically pruned only each year, whereas trees on the left were hand pruned following mechanical pruning each year. Hand pruning following mechanical pruning opened up the tree by removing excess shoot development. Results and Discussion Use of the mechanical pruner destroyed the desired shape and framework of the tree. As many as 8-10 shoots developed around each cut made by the mechanical pruner if detailed hand pruning did not follow, figure 2. Mechanical pruning alone resulted in trees with a thick canopy which suppressed spur formation, shaded out fruiting wood in the interior of the tree, made insect and disease control difficult, and prevented fruit from developing red color, figure 3. A combination of mechanical and hand pruning each year reduced pruning time over that of hand pruning alone, table 1. Mechanical pruning prior to hand pruning reduced the time required to hand prune by 40, 39, 22, and 32 percent, respectively, in the 2nd, 3rd, 4th, and 5th years. The plots which were mechanically pruned each year and hand pruned in alternate years did not differ in time required to hand prune in alternate years (years 3 and 5) from the hand pruned only treatments. However, the hand pruning time was reduced approximately 50 percent over the 4 C Z 0 Z -4 TABLE 1. EFFECT OF MECHANICAL PRUNING ON TIME REQUIRED To PRUNE VANCE RED DELICIOUS APPLE TREES ON MM 106 R)TSTOCK Time per replication (10 trees) Treatment Hand 1972 Machine Hand 1973 Machine Hand 1974 1 2 0 1976 1975 Machine Hand 0a Min. Mechanical prune only .......... Mechanical prune plus hand prune ......... Min. 5.5 b Min. 0a 104 a 113 a 2 Min. 3.3b 3.1lb Min. 0Oa Min. 3.2 a 3.2 a Min. MM. 3.3 b Machine Hand Machine 0 r- Min. 0a 3.7 b 0a 3.7 b Min. 0a 0 Hand prune only ............. Mechanical prune annually rune1st, pplushand 3rd, 1468b Lil1a 4.3 b Oa 149 b 249 c 0a 266 c 271c ?5a 163 b 232 b 0a 296 c 240 b 355 c 315 bc 3.4 b 3.3b C and 5thyears................ 4.8b 0Oa 3.0Ob 0Oa b 3.5 m {A ' Experimental trees were established in 1964 and were in their ninth leaf at the initiation of the experiment in 1972. =Mean separation, within columns, by Duncan's multiple range test, 5 percent level. 8 ALABAMA AGRICULTURAL EXPERIMENT STATION years due to alternate year pruning. Time necessary for mechanical pruning (lid not vary between mechanically prunedltreatments. Yield was not significantly affected by pruning methods, table 2. The general trend was for tnechanically plus hand pruned trees (treatments 2 and 4) to produce higher yields than either hand pruned or mechanically pruned trees. pruned TlICnta l~i 2. I)tiucious APnlE'if, t* s ()N MM 1972 EATtN- 'MPHUNIN e MM5t'tic ON YI.o 106 1OOTSTOCK 1973 1974 (OFVANCE 'Treatment Yield per tree' 1975 1976 Lb. Lb. Mechanical prune only.................. 126 a2 174 Mechanical prune plus hand prune...........118 a 160 a a Lb. 158 a 192 a 140 a Mlechanical Ihland prune only..:..................... annually plus hand prne prune 1st, 3rd, and 5th years ............ .. 06 a 'j 142 a Lb. Lb. 128 a 157 a 170 227 a 136 ah 189 a 126 a were in their ninth leaf at the initia'Th'ie experimental trees were established in 1964 tioni oF the experiment. 2 Mean separation, within columuns, by )uncan's n ultiple range test, 5 percent level. and 180 a 190 a b 160 al) 22.3 a Light penetration into the center of hand pruned trees was 4 JO times greater than for mechanically pruned only trees, table 3. Small differences were recorded for light penetration into the branches on the outer periphery of the tree. The heavy pruning necessary to Maintain the trees at an 8-foot fruiting height was too severe and resulted in excessive vegetative growth each season. In a different experiment in which the same age scion-rootstock combination was mechanically pruned, trees -reached a bearing height of _14-16 feet before excessive vegetative growth was arrested and large annual crops were produced. The time required to hand prune was versely eced mechanical pruner prior to hand pruning, and yield was not ad- reduced by use of the affected. owever, this investigation indicates that mechanical pruning to maintain an 8-foot fruiting height is not satisfactory for high density orchards in Alabama due to effects ont color development, light penetration, and tree shape. The results may have been different had a greater fruiting height been maintained. PRUNING AND TRAINING 'IA 3lE :3. RED DELICVOUS APPLES 9 1NItI E-NC;E1O' I 'NINC tMTIo i) ON Licirr PENTBAI(N PB INTO) n'AhIIOIS I)ErTIIs 'T'EE CANcOPY' OF ~IreatInent Top canopy of light tree canopy, foot candles readlings at 1 foot 2 various positions in feet 3 feet 4I feet 131.:3 JUNE 17 NMechianical prune only ........ Mechanical prunie hand primn(............... plus 10,562.5 10,550.0 . 450.0 Center 262.5 850.0) 12.i.() 85().() 775.0 I land Mechanical prune annually plis hand prune 1st, 3rd and 5th years .............. only ........ NMechianical Mechanical jirune phits hand prine ................ I and prime only ............. Mechanical prone anntall I pius hand prune 1st, 3rc and 5th years ............. prune only., 2,425.0 ........... 10,450.0 10,050.0 4,475.0 1,562.5 1,2,50.0 312.5 :375.() 6 75.() 256.3 lOOt) 287.5 prtie Ouiter periphery 10,550.0) 3,875.0 2,075.0 8:37.5 10,675.0 10,362.5 . 10,02,5.0 2,812.5 2,887.5 1,325.0 4,650.0 637.5 750.0 .enter 387.5 726.0 900.0 675.0) 2.37.5 287.5 65() 212.5 1750( 102.5 275.0 (i50).( JUNE 27 Nlechianical prime only........ Mechanical prune plus1 hand prine................ 9,900.0 9,737.5 9,737.5 9,950.0 9,826.0 9,775.0 9,800.0 9,750.0 875.0 1,787.5 1,287.5 275.0 962.5 1,537.5 Iand prune only ............. Mechanical pirune annually plis hand 1st, 3r, and 5th years. I'mine .. . .. . .. . .. "". Mechanical p~rune only ......... Mechanical prune p~his hand pruine ................ land prine only ............. 350.0 212.5 131.3 Outer periphery 3,487.5 1,150.0 500).0 5,550.0 3,626.0 2,726.0 275.0 :312.5 '100.) 1,0)12.5 4137.5 I Mechanical prune antmafll 2,412.5 1,150.0 1,67 1,212.5 537.5 775.01 the llies hand pluetllC1st, 3r, and 5th years .............. were made above the tree canopy and at depths of 2, 3, and canopy at both the center and in the outer periphery. 'Light readings olbtainled with Weston Model 756 sunlight 1, 5.0 ilttininationameter. li 4 feet from top iing, of the TREE SPACING AND LIMB POSITIONING' EXPERIMENT Wellspur planted in January 1969 with spacings of 5, 7.5, and 10 feet between trees in the row and 22 feet between rows. Trees were trained to a modified central leader with major scaffold branches developed at a 65- to 90-degree angle to the trunk axis by the lise Red Delicious apple trees on MM 106 rootstock were 10 ALABAMA AGRICULTURAL EXPERIMENT STATION ._. FIG. 4. Branches were placed in a horizontal position by pulling them down and tying them in position. of wire braces during the first few years of the tree's life. In the spring of 1973 the trees were topped at a height of 8 feet with a Fossu n tree pruner, followed by uniformly detailed pruning by hand. The 5-foot spaced trees had formed a solid tree wall at this time. A randomized complete block design with four replications of 5-tree plots was utilized to determine how tree spacing, conventional training, and horizontal placement of all major scaffold branches affected weight and number of fruit produced. With trees spaced 7.5 and 10 feet, branches were placed in a horizontal position by pulling down and tying them in position, figure 4. Weight and number of fruit per tree were recorded from 1974 through 1979. No yield records were recorded in 1978 due to poor fruit set. Results and Discussion The accumulated yield was higher for 5-foot spaced trees than 7.5- and 10-foot spaced trees on which the major scaffold branches were not spread, table 4. However, the 10-foot spaced trees with major scaffold branches spread had an accumulated PRUNING AND TRAINING RED DELICIOUS APPLES 11 1 'I'Antt. 4. [ Fi-cci 1' ' I'lEESPACING ANt) Treatmient of major scaffoldl LIMB POSITIONING ON YIELDOFrWEtiSeM tIII l)Iru~Cv( us Atrt .r TRES ON MM11)6 ROOTS'TO(;K RED Accurn- Ibranches 1974 Yield per acre, by year 1977 1976 1975 idlated 1979 yed acre 10-ft. spacing. in. row'. . 2 .. . . . .. . .. . .. Tied, . Not tied.......... ............ .. . .. 256 19 313 be 346 a 217 h 305 a 369 a 7.5-ft. spacing Not 275 c 538 h 409h1 1,004l a in row "iecl........................... Not tied(..................... 260 b 464 a 428 a 410 a 360 abc 297 a 391 ab 353 a :3911)87 1,9 404 a 953 ab 2,1591h 688 bc 2,28(3 h (6(36thc c 508 2,157 b 5-ft. spacing in row '"Frees stpaceld 5, resj)ccti' e ly. tied........................ Scaffold experiment. scaffold brantches w~ere not of trees that were trained to a central leadler and1 the miajor we re tied to a horizontal p~osition. 'Mtean 7.5., nd 10 8.15 a c2,531 a feet apart in)the row equIlals 396, 26i4, antel 198 trees per acr e, 2'111(, mjor lbranches p~resent on the 5-year-old central leadler tree tiedI The not-tied treatmient consisted to a horizontal p~osition at the initiation of the separation, within colunnuts, lby luncan's multiple range test, 5 percent 1(eeI. yield equal to the 5-foot spaced trees. Limb spreadling increasedl the accumulated yield of the 7.5- and 10-foot spaced trees lby approximately The 5-foot spacedl trees produced higher yields in the early years, but the 10-foot spaced trees produced more in 1979. The 300 bushels per acre. PER number of fruit produced per acre followed the same trend as the TABLE 5. EFFECT OF TREE SPACING AND PRODUCED BYWELLSPUBt RED DELicious APPLES ON MM106 ROOTSTOCK ACRE LIMB POSITIONING ON NUMBER oF Fni lr ajreaffold o btr aches Number fruit/acre, by year 1974 1975 1976 1977 1979 No. 10-ft. spacing in brow' liei.................... Not tied ..................... 7.5-ft. spacing in row Not No. No. No. No. 28,789 b3 35,155 bc 31,314 a 66,904 1b113,078 alb 26,245 b 28,898 c 25,610 a 49,179 h l09,(965 al, 43,904 'lied(.I....................... tied...................... 29,898hb in row .. """"".... ab 48,075 a 37,224 a 54,138 b 36,458 be 25,610 a 50,51711) 82,1311) 83.768 h 5-ft. spacing Not tied 59,697 a 42,234 ab 30,427 a 108,445 a 142,117 a a horizontal position at the initiation of the experiment. The not-tied treatment consisted major scaffold branches were not tied of trees that trained a central leader and '''rees spaed 5, 7.5, and 10 feet apart in the row equals 396, 264, and 198 trees per acre, I1'e majo~;r scaffold branches p~resent on the 5-year-old central leader tre(es were tied~ to to a horizontal position. :IMeain serat'_tion, tii were to the coumslby Duncan's multple range test, 5Ir'nt level. 12 12 ALABAMA AGRICULTURAL EXPERIMENT STATION r .f AND) or Tiur SI'ACINC: IIMB PIsn()s'IONINC,(ON AvRnc WniiOr Fi isOK lll) ) D;!,iciois A{''!;.E Tmi.s ON NINI1100 1100! (. ErFrrc TABLEi litl'l(:Ep BY WEM~fL I''t ii Treatment m abranches of scaffoldlfruit cor Individual fruit weight, by year 1974 Lb. Average weight 1975 Tied; 10-ft. jL. 1970 Lb. 1977 1979 Lb. Lb1. Lb. spacing in row' ......................... ......... Not tied ......... 7.5-ft. spacing in row lie'd...... .................... Not tied................... 5-ft. spacing in row Not tied...................... .0.:36 a 0.358 a 0.438 a 0.323 a 0377 a 0.371 a) :.....360)a .386 a .474 a .3:31 a .,351 a .380 a . ' .:356 a ... 17 a .391 a ,315 a .440 a .449 a .465 a .290 a .32( a .329 a .353 1) .322 a1) .364 ab .371 a :30) a .210 b .332 b '"frees spaced .5, 7.5, and 10 feet apart in the row equals 396, 261, and 198 trees per acre, reslpectivelIy. 2'1'1re major scaffold branches lresent on time 5-year-old central leader trees were tied to a horizontal position at the initiation of the experiment. he not-tied treatment consisted to a central leader and the major scaffold branches were not of trees that were ii tied to a horizontal position. :'Mlean selparatiomi, within coluMns, by Il)nncan's multiple range test, 5 percent level. trained method did not affect average fruit weight, table 5. weight, table 6. 10-foot spacing is better for "spur type trees on MM 106 rootstock than the 5- and 7.5-foot spacing. The closer spacing requires more plants per acre, and the 5-foot spaced trees soon become crowded and begin competing among themselves, figure 5. Major scaffold branch positioning develops a tree that has the Ipotential for producing large crops in the future. The Pruning CONCLUSION Results of the research reported emphasize the need to properly train and shape an apple tree in its early years and maintain this pruning destroyed the tree shape and led to the formation of a thick canopy, which prevented light penetration into the center of the tree pruned to an 8-foot height. Hand pruning (developeda mlore desirable tree. DISCUSSION AND RECOMMENDATIONS form for the duration of the orchard's productive life. Mechanical experiments, as well as on. other available data, certain general statements and recommendations concerning apple tree training and pruning can be made. Based on recorded results and observations made during the PRUNING AND TRAINING RED DELICIOUS APPLES 13 FIG. 5. The 5-foot spaced trees were crowded and competing among themselves in the fifth growing season. The ideal shape would have all leaves on the tree intercepting a maximum and equal amount of light. A perfect distribution of light would result in the vegetative growth being evenly distributed throughout the tree and fruit being of uniform size, quality, and maturity. In addition, the light intercepting leaf area and fruiting wood should be close to the ground to facilitate cultural practices and harvest. To achieve these goals, the growth pattern of the scion variety-rootstock combination must be considered when planning the orchard and the trees must be properly trained in the early years of the orchard's life. The central leader tree form (pyramidal or Christmas tree) for free standing or staked medium density plantings of apples is preferred to maximize light penetration into the center of the tree and light distribution along and between trees, figure 6. Methods of training high density, free standing apple trees to a central leader system have been reported by several workers (1, 10, 13). These methods, with modifications, were used in developing the following procedure for training free standing, high density apple trees and maintaining them. 14 ALABAMA AGRICULTURAL EXPERIMENT STATION FIG, 6. This is a well shaped spur type Red Delicious apple tree on MM 106 rootstock in the third growing season. The first two tiers of branches have been developed. Newly set trees should be pruned immediately after planting, before gEowth begins, to a height of 28 to 30 inches. This will force the first scaffold branches to develop at the desired height. When the new branches are 3 to 6 inches long, remove all branches lower than 20 inches above the soil line. Three to five branches that are 2 to 6 inches apart and spiraling up and around the tree should be selected, with all other lateral branches removed by rubbing them off. The selected branches will form the first tier or whorl of branches. Train the selected branches to form a wide crotch angle by using spring-type wooden clothespins, round toothpicks, or short wires (number 9 clothes line wire) sharpened at both ends, figures 7, 8, and 9. The braces should be put in when the branches are 3 to 6 inches long and set so that the branches form a 90-degree angle with the main axis of the tree. Remove the clothespins to prevent girdling when shoot tissue PRUNING AND TRAINING RED DELICIOUS APPLES 15 FG. 7 Wo....lte is.c...b...e.......d...A....... br. o ° . FIG. 7. Wooden clothespins can be used to develop the Initial branch angle of 90 FIG. 8. Round wooden toothpicks can be used to develop the proper branch angle. 16 ALABAMA AGRICULTURAL EXPERIMENT STATION lignifies or hardens, usually by mid-July in the same season. It should be noted that clothespins or other small devices are initial training aids and not substitutes for long limb spreaders to be used later. The toothpicks and wire braces do not have to be removed that season. All other branches that develop in this area should be removed when they begin growing so they do not compete with the selected scaffold branches. This will develop the first tier of branches. Three or four tiers of branches will usually be needed to form the ideal tree. The second, third, and fourth tiers should be at least 20 to 24 inches apart on spur type trees and 24 to 36 inches apart on non spur type trees. It will take 3 to 4 years to develop the third- or fourth-tier branches. The procedure used to develop the first tier of branches should be used to develop the second, third, and additional tiers of branches. When a tier of branches is selected and formed, the terminal of the leader should be removed about 36 inches above this tier to facilitate branch development for the next tier. All branches should be removed as they start to develop between the tiers of branches. When developing the second and higher tiers, shoots should be selected that have an area of their own to intercept light without casting excessive shade on lower limbs. To accomplish this, the ,ove t I . : the1' i ~ t . '. I ~is ter ;irmin ! r- t { 7. FIG. 9. Wire spreaders can be used to develop the proper branch angle. PRUNING AND TRAINING RED DELICIOUS APPLES 17 * . r . " FIG. 10. This is a well trained 3-year-old tree with two tiers of branches developed. The branches in the second tier are positioned between and not directly above a branch in the lower tier, so that shading is minimized. branches in the tier above another should be positioned between and not directly above a branch in the lower tier, figure 10. The branches that were forced to form a wide angle at their bases will turn and grow upward as they elongate. Thus, after clothespins are removed from newly formed scaffolds (in midsummer of the first year), it is usually advantageous to continue the branch spreading process using longer spreaders. If trees have made sufficient growth, new spreaders may be placed on branches in late summer of the first growing season. Otherwise, new spreaders should be positioned on branches during the first winter. Tree development will dictate when additional spreading should be done. Branches should be initially braced to form a 35- to 45-degree angle with the main axis of the tree. Spreading the limbs to a more horizontal position at this time encourages the development of undesirable, strong, vertical shoots on the tops of scaffold limbs. As branches become large enough to fill their allotted space, they may be spread further to about a 60-degree angle from the central leader. The branches can be spread using wood spreaders, wreaderseaders, or wires, figure 11. Spreaders will need to be used for one and possibly two or more seasons. 18 __ 18 ALABAMA AGRICULTURAL EXPERIMENT STATION FIG. 11. Wood spreaders can be used to improve the crotch angle on larger limbs. Suckers arising from trunk and scaffold branches should be removed tWo or three times during the growing season ly rubbing the tendler shoots off. In some instances a side branch will not develop at the desired location on the trunk of a tree. If a scaffold branch is needed in a particular spot on the tree, you can force a dormant bud by making a 1-inch cut through the bark parallel to the above a bud on young trees and 1inch above a 1)11( on older trees, figure 12. Apple trees trained by the above procedure will have a suaff icient number of well placed scaffold lbranches. A maximitumnumber of horizontal fruiting branches sIhouldl be dleveloped near the tree axis on each scaffold branch. If the fruiting branches are dlevelop~ed near the tree axis, this will eliminate the need to prop the scaffold branches when the tree starts producing heavy loads. Fruiting spurs should. be developed from the sidles of the horizontal fruiting branches. fruiting spurs (leveloping from the sides of the fruiting branches are more jprodluctive and pro(Itice larger, higher colored fruit. spurs that (levelol) on the lower side of the branch are weak and prodluce small, less colored fruit. Fruiting spurs that (levelop from the top of the ground, /12 inch The Fruiiting PRUNING AND TRAINING RED DELICIOUS APPLES 19 branch are less productive, more vigorous, and subject the fruit to limb rub and sunburn. Annual pruning of bearing trees is essential throughout the lifetime of an orchard. The introduction of size controlling rootstocks and the pyramidal form for tree training has resulted in changes in the conventional manner in which bearing trees are pruned. The need to prune trees in high density plantings to maintain them within their allotted space is considerably more iniportant than with larger trees grown on wider spacings. 'ree vigor must be kept adequate, but not excessive, to produce optimum yields of top quality fruit. To achieve all of the desired effects from pruning higher density plantings requires a limited amount of summer and winter pruning annually. Sunti er pruning is more dwarfing than winter pruning, but both types are necessary in properly managing modern apple orchards. Bearing apple trees should be pruned during the winter prior to bloom development. Pruning at this time is stimulative and should not be overdone to avoid excessive shoot growth in the spring. This form of pruning is quite useful for thinning out excessive limbs and reducing tree height while maintaining sufficient vigor in the tree top. It is important to maintain the central leader as a strong vegetative shoot on bearing trees. This is most easily achieved through annual heading back of the 1-year-old terminal portion each winter. Sometimes it may be necessary to leave only one or two buds of the previous year's growth. Trees on semi-dwarfing rootstocks (M7A and MM 106) can be main- FIG. 12. If a scaffold branch is needed in a particular spot on the tree, a dormant bud can be forced by making a 1-inch cut through the bark parallel to the ground (arrow, left photo), 12 inch above a bud on young trees and 1 Inch above a bud on older trees. Result of the cut is evident in the right photo (arrow points to old cut). 20 ALABAMA AGRICULTURAL EXPERIMENT STATION tained at a height of 14 to 16 feet and trellised trees at a 7- to 8-foot height through annual topping as just described. If the trees grow too high, too quickly, lower branches may not develop properly. To correct this situation, the top may be cut back substantially (in 2-year or older wood) during re 4lar winter pruning. The idea is to develop vigor evenly throughout the tree in all scaffolds while keeping the tree in its allotted space. )Duringthe training process, heading cuts are used to stiffen the central trunk and lateral scaffolds and cause more branching and spur development. As trees begin regular bearing, the numof heading cuts should be reduced. If lateral branches are long enough to fill the allotted space, the terminal shoot should not be headed back. A thinning cut should be used to reduce the vigorous terminal shoot to a weaker side or terminal shoot which should be left unheaded. The object is to discourage further growth in that area. Thinning cuts should be used to replace most heading type cuts in older bearing trees (except for the terminal of the central leader which must be headed annually). Some heading cuts will be needed to replace fruiting wood where growth has become too slow. ber The thinning out and heading back cuts on the central leader and lateral scaffolds are among the most important aspects of winter pruning. Normally, excessive inside shoot growth is handled with summer pruning, but it still may be necessary to remove any undesirable shoot growth developing on the upper sides of branches and where crowding of branches is occurring. Large limbs which are crowding other scaffolds may be removed in the winter by cutting back to a side branch. D)ead, diseased, weak, and unproductive wood should also be removed. It is important to keep the center of the tree around the trunk open to permit spray materials and light to better penetrate the tree. Do not leave stubs when pruning unless cuts are being made for spur development. Cut back to a lateral branch in the direction of desired growth. Pruning during the growing season can dwarf or devitalize apple trees. The degree of dwarfing resulting from summer pruning is related to the amount of leaf area removed. Early season growth is produced at the expense of stored materials in the tree. After the leaf area has developed, carbohydrates manutfactured in the leaves begin to feed back into the storage areas to be used dluring the following season. With summer rtuning, PRUNING AND TRAINING RED DELICIOUS APPLES 21 leaf area is removed before the feedback process is complete. The later in the season that summer pruning is done, the more leaf area is removed and the greater is the dwarfing response. Summer pruning is an important step in properly training young apple trees. It can be used to direct growth into desired growing points on young trees and actually result in larger and better shaped trees than non summer pruned trees. If sunier pruning is done just after the shoots start to grow and are only a few inches long, little actual leaf area is removed. Summer pruning can be used to direct growth into desired growing points in the following ways: 1. Shoots headed during the dormant season usually develol two or three vigorous shoots from buds immediately below the cut. One or two of these shoots can be removed early in the growing season to direct the growth into a single shoot. 2. After branches have been selected to form the scaffold branches for each tier, the remaining shoots in this area should be remnoved by rubbing off. 3. Shoots developing on the trunk between the tiers of branches should be removed just after they begin to develop. :. FIG. 13. Spur and flower bud development occurs following summer pruning between July 15 and August 1. 22 22 ALABAMA AGRICULTURAL EXPERIMENT STATION 4. When the major scaffold branches are braced out to the desired position, several strong shoots normally (evelo) in the leIld area on the upper side of the branch. Thlese shuldlbe removed )y rlbling I)rior to lignification. 5. Apical dominance can be tlr oken on vigorous shoots removing terminal bud and thus promoting the (cvclopmcnt of side shoots. Flower bud formation can be enhanced on current season's growth by pruning the shoots back to two or three lateral buds between July 15 and August 1, figuire 13. After heading, the remaining buds will make short shoots that often form terminal flower "this practice is generally effective on young trees when upright shoots on the main scaffold andhorizontal branches are headed back. However, heading back current seashoots early in the growin season will nsually resnit in the remaining lateral buds making excessive growth. In general, snrenmer pruning in late Jutly and early August will reduce growth the by buds. strong son's aidl in developing a fruiting andl system for the followving season. Proper training and care of ap~ple trees in the early years of the orchard's life will enable the grower to cope with labor shortages andl increasing production cost in properly managing the orchard for production of quality fruit in later years. Properly trained trees will produce large, high quality crops at an earlier age than trees that are allowed to grow for several years and then trained. Trees that produce large crops at an early age make less vegetative growth, in later years. thus requiring less pruning andl management PRUNING AND TRAINING RED DELICIOUS APPLES 23 2 LITERATURE CITED (1) BANTA, E. S., F. S. IIOWIETT, AND R. C. HILL, JR. Pruning and Training (2) (3) (4) CAIN, (5) (6) (7) (8) (9) (10) Fruit Trees. Ohio State Univ. Ext. Bull. 528:1-24. J. C. 1971. Effects of Mechanical Pruning of Apple hedge flows with a Slotting Saw on Light Penetration and Fruiting. J. Amer. Soc. hlort. Sci. 96:664-667. CAIN, Jot IN C. 1972. Slotting Saw Pruning of Hedge flow Apples Improves Production'and Quality. Cornell Univ. Food and Life Sci. Bull. .15:1-4. COPE, J. T. ANI) I. L. KIRKLAND. 1975. Fertilizer Recommendations and Computer Program Key Used by the Soil Testing Laboratory. Auburn Univ. (Ala.) Agr. Exp. Sta. Cir. 176. FERREE, D. C. 1976. Influence of Slotting Saw Mechanical Pruning and Alar on Apple Fruit Size and Quality. Ohio Agr. Res, and Iev. Center Res. Cir. 220:3-7. FoSIIEY, C. C. 1970. Mechanical Hedging and Topping of Fruit Trees. Eastern Fruit Grower. Mar. 1970. p. 4. CIUI3ERTr, E. J. 1964. Mold and Hold a Profitable System of Pruning. American Fruit Grower. Mar. 1964. p. 18. IIA.SEILY, D. C., C. 1). MCCARTY, AND S. B. BOSEWELL. 1972. Desert Crapefruit Pruning and Orchard Thinning Trials. Calif. Agr. 20(3):7-9. hANSEN, C. F., R. P. LARSEN, AND C. MONROE.1968. Pruning of Fruit Trees. Mich. Agr. Exp. Sta. Quart. Bull. 50:331-341. 1975. High-density Apple Orchards--Planning, TrainH-EINICKE, DON 1R. fledge ing and Pruning. USI)A Agr. Iles. Ser. Agr. Handbook 458:1-34. (11) KELSEY, M. P., S. B. HAIISII, AND H. BETTER. 1971. Economics of Apple Production in Southwestern Michigan. Mich. State Univ., Agr. Leon. lipt. No. 184. (12) MCBIRNEY, S. W. 1968. It's True: Dwarf Trees Can Be PickedI Faster. Western Fruit Crower. Aug. 1968. p. (13) POWELL, A. A., T. B. I-IAGLER, AND W. A. DOZIER, JR.1979. Fruit Culture in Alabama. Ala. Coop. Ext. Ser. Cir. ANR-53. pp. 10-12. (14) SMIT!!, 0. CECIL MAURICE FERREE. 1969. Apples Enterprise Cost Analysis. Coop. Ext. Ser. Univ. of Ca. College of Agr. Misc. Pub. No. 82. (15) STROIlIEB, C. IR., W. CAZAWAY, A. A. POWELL, A. J. LATIhA NI. 1979. Alabama Spray Schedule for Commercial Apples. Ala. Coo1). Ext. Ser. Cir. ANR 11. 8-9. AN!) ANI) , 1ca~ rN ii 7W Nr i:' With. an agricultural research unit in every major soil area, Auburn University serves the neets of and '0 (~) ii field crop, livestock, forestry, () hor- ticultrlal producers in each. region in Alabama. Every cii- f zen of the State has a stake in this research ilAt c~1T UŽ ii program, since any advantage from new and more economical ways of producing andl handling " i N farm I.. products diI- rectly benefits the consuming public. Idv(t't(la1 CI) IlIn ewI dWtI(a~ SMain Agricultural Experiment Station, Auburn. SE. V. Smith Research Center, Shorter. 1. Tennessee Valley Substation, Belle Mina. 2. Sand Mountain Substation, Crossville. 3. North Aabama Horticulture Substation, Cullman. 4. Upper Coastal Plain Substation, Winfield. Fayette County. 5, Forestry Unit,Seed Stocks Farm, Thorsby. 6. Foundation Coosa County. 9. Piedmont Substation, Camp Hill. 10. Piant Breeding Unit, Telassee. 11. Forestry Unit, Autauga County. Area Horticulture Substation, 7,Chilton Clanton. 8. Forestry Unit, 12. Prattville Experiment Field, Prattville. 13. Black Belt Substation, Marion Junction. 14. The Turnipseed-lkenberry Place, Union Springs. 16. 17. 18. 19. 15. Plain Substation, Lower Coastal Barbour County. Camden. Forestry Unit, 20. Solon Dixon Forestry Education Center, and Escambia counties. 1.Ornamental Horticulture Field Station, Spring' Hill. 22. Gulf Coast Substation, Fairhope. YCovington Monroeville Experiment Field, Monroeville. Wiregrass Substation, Headland. Brewton Experiment Field, Brewton.