N.C. Apple fififi Praduction IHa_llllahl Cultural Practices Training and Pruning Apple Trees Tree training and pruning are the two most basic horticultural orchard management practices. Training can be defined as a process of selecting the proper number and placement of scaffold limbs in a tree as well as developing the overall shape, size and light penetration of that tree. This process is generally completed by the time a tree reaches full bearing age around 6 to 8 years old. Proper tree training requires the grower to be aware of the number, position and angle of lateral limbs. A good angle of lateral limb attachment to the leader must be obtained since these points of attachment will carry the fruit load for the life of the tree. The proper number and position of scaffold limbs is necessary for good light penetration in future years. The overall benefits of training are healthy spur formation, adequate flower initiation, good fruit size and color, and easy picking. Pruning, sometimes called maintenance pruning, can be defined as the on-going process of maintaining Viable and productive bearing wood within the tree, maintaining prescribed tree shape and height, and maintaining tree size within the row space allocated. Pruning is the only way a grower can maintain the proper light penetration into the orchard canopy during its bearing years. Proper light penetration is essential for the continued Vigor and productivity of fruiting wood developed earlier in the tree training process. A vigorous and productive spur must receive full sunlight for 30 percent, or more, of the day. In addition, pruning contributes to annual bearing by helping prevent biennial bearing. Recently, research has shown that annual maintenance pruning has a direct stimulatory influence on fruit growth. Orchard planning and planting decisions such as tree and row spacing, variety, expected maximum allowable height, etc. have a great impact on training and pruning for the life of that orchard. A separate chapter on Planning and Establishing Commercial Apple Orchards in North Carolina is included in this manual. A good rule of thumb for tree height and row spacing is the cross or between-row spacing should be twice the height which the tree will be allowed to obtain; e.g., if trees are to be held at 12 feet, then crossrow spacing should be 24 feet. Following this rule insures maximum light penetration and adequate space between rows. Newly Planted Trees Central Leader Training. Some nurseries will ship trees for fall planting, while others ship only for spring planting. Regardless of when trees are planted, newly set trees should be pruned only in the spring after the chance of severe freeze is past. At pruning time, remove all side limbs and cut off the leader or terminal 30 to 32 inches above the ground. When new growth is 1 to 2 inches long (late April to mid May), identify the shoot which will form the new leader, leave it and remove all new shoots for 4 to 5 inches immediately below this new terminal (Fig. 1). If not removed, these shoots would be very upright, have a sharp crotch angle, and would compete with the new leader. Removal releases and encourages the development of buds or shoots in a zone from 6 to 14 inches below the cut tip of the tree (Fig. 2). The lateral limbs formed from shoots in this zone are more desirable because they are less vigorous and upright, less competitive with the leader, and easier to train into productive scaffold limbs. This technique also insures that the first whorl of scaffold laterals is produced at a height between 18 and 22 inches above the ground. All new shoot growth below this should be stripped off in late April or mid May to prevent competition with desired growth (Fig. 3). Trees should then have one terminal shoot to form a new leader and one 8 inch zone of shoots to form the first whorl of laterals. All other new growth must be removed early in the season. This insures that the tree s growth and vigor is directed toward development of a useful tree structure for its bearing years. Scaffold Training. When the first whorl of lateral shoots is 4 to 6 inches long but still quite succulent, the grower should select four to six well-spaced lateral shoots as potential scaffold limbs and spread these to a 70- to 80-degree angle with the leader using
Fig. 1 In the spring when new terminal growth is 1-2 inches, identify the new leader and strip all new shoots 4-6 inches immediately below the terminal. A shows the young tree before stripping; B shows how it should look after. v _ w:m, ifiré,x \' Fig. 3 This is a newly planted tree with the top Fig. 2 New lateral shoots are released in a zone and bottom shoots stripped and the first whorl of 6-14 inches below the stripped terminals. laterals at 18-22 inches above the ground.
toothpicks, Clothespins, etc. All other new lateral shoots should be cut off at this time and all fruit removed (Fig. 4). Spreading insures a wide crotch angle and strong attachment of the scaffold limb to the leader. These spread shoots will curve back upright and need to be spread next spring; however, establishing a good angle while the shoot is succulent is essential. It is very hard, if not impossible to alter the crotch angle with later limb propping. No pruning should be done on trees after July until the next spr ing to prevent winter injury. One Year Old Trees Dormant Training. Dormant training and pruning on 1 year-old trees should be done in the early spring, after the risk of hard freeze is past but while trees are still dormant. Cut the leader off approx imately 20 to 28 inches above where it was cut off last year. This will space the whorls of scaffold limbs about 2 feet apart. By doing this each year, a 6-yearold tree should be 12 to 13 feet tall and have six whorls of scaffolds. At the end of these 6 years, the tree scaffold system will be complete. Maximum tree height will be established at 13 to 14 feet, and fruit bearing will be well established. Pruning emphasis will shift to holding tree in its allotted space, providing good light penetration, and maintaining the tree in an inverted cone shape (Fig. 5). Select three to four (very few trees Will have five) of the best and most equally spaced laterals that were spread the first year and cut all remaining lateral limbs that grew during the last season off the leader. Cut the tip off the selected three to four laterals so that each is about 18 to 24 inches long. By selecting three to four laterals per year, a 6-year-old tree will have 18 to 24 scaffold limbs. This number represents the maximum number of scaffold limbs a productive, space-contained, central leader apple tree should ever have. Tipping, or cutting back, the laterals strengthens them and encourages branching. A strong and highly branched limb is desirable for future support of crop load and production of secondary fruiting wood. When new growth is 1 to 2 inches long, follow the procedure for removing shoots in the first 4 to 5 inches below the leader and the bottom 18 inches above the ground as described for newly planted trees. The new terminal of each lateral limb should be selected, and all other new shoots stripped off for 4 to 5 inches below the tip, just the same as described for the central leader terminal. At this time, remove all flowers and fruit from the tree. Fig. 4 When the new laterals have grown 4-6 inches, spread them to the correct angle with toothpicks. Fig. 5 Train young trees to an inverted cone shape.
When new lateral shoot growth is 4 to 6 inches long, spread four to six lateral shoots in the second whorl. Spread three to four laterals that were established last spring in the first whorl to a 40- to 50- degree angle with the leader with 6- to 8-inch-long wood or wire props. Spreading reduces the vigor of the lateral limbs and encourages secondary branching and flowering. Summer Pruning. Each year, during the last half of June or July, make an additional trip through the orchard to remove any secondary shoots that have reestablished upright growth or originate from the top side of scaffold limbs. Remove any new growth that has developed around old pruning cuts (Fig. 6). This type of shoot removal is called summer pruning, or more correctly summer deshooting. Summer deshooting should be done each year on all scaffold limbs 1 year old or older. It is usually done two to three times a year (usually during May, June and July) on 2-year-old and older nonbearing or lightly bearing trees and once or twice a year (usually late May and mid July) on bearing trees. Summer deshooting is most effective if shoots are broken or stripped rather than cut; however, if timing is too late and pieces of bark pull off with the shoot, they should be cut. On young trees, summer deshooting reduces undesirable, or junk, growth and directs vigor to scaffold limbs and fruiting wood production. On bearing trees, summer deshooting allows better light and chemical spray penetration, keeps fruiting spurs healthy, and improves fruit size and color development. It has been found that summer deshooting is a less expensive and more efficient use of labor and requires less skilled labor than dormant pruning. It also cuts dormant pruning time and costs substantially. Our North Carolina experience suggests a 30 to 50 percent reduction in dormant pruning time. Two Year Old Trees Dormant Training. During March, prune dormant 2-year old trees. These trees now have two whorls of scaffolds on them. Cut the leader off 2 feet above last year s cut on the leader. Select three to four scaffold limbs from the top whorl which were allowed to grow last summer and head back to 18 to 24 inches as described for a 1-year-old tree. The bottom whorl (now 2 years old) grew in length and developed secondary branching last season. Cut the tip off the ends of the scaffold limbs so the shape of the tree resembles an inverted cone (A). The limbs should be pruned enough that the outer limb tips form a cone with the sides having an angle of approximately 45 degrees. This shape will generally be formed when 2-year-old scaffolds are shortened to 3 to 4 feet. Remove any riser shoots (water sprouts) or shoots from old cuts that were missed in summer deshooting (Fig. 7). Spring and Summer. When new growth is 1 t0 2 inches long, strip the shoots below the leader as described earlier for newly set trees. At 4 to 6 inches Fig. 6 This is a 1-yearold tree with scaffold limbs propped and riser shoots removed.
of new lateral growth, spread four to six new shoots. This will be the third whorl. Spread scaffold limbs selected last year (the second whorl) and remove water sprouts and shoots from old cuts. The bottom whorl of scaffold limbs will need longer spreaders-(12 to 18 inches) to bring the tips back to a 45-degree angle with the leader. Remove the smaller spreaders put in the bottom whorl last year and move them up to the second whorl. Reusing spreader props can continue up the tree to the next younger whorl until maximum tree height and scaffold selection stops. During June and July, deshoot all 1-year-old and older scaffold limbs. Three Year Old Trees Dormant Training. During late February or early March, dormant prune the trees by cutting the leader back to 2 feet above last season s growth. Select three to four 1 year-old scaffold limbs from last year s whorl and cut 2- to 3-year old lateral (scaffolds) tips back to form an inverted cone. At 3 years of age, the lower whorl of scaffold limbs has considerable secondary and tertiary branching. Some of this growth may have to be thinned for light penetration and spur formation. As new growth starts during the fourth year of growth since planting, the lowest scaffold whorls should have produced a number of fruiting spurs and should begin to flower and bear some fruit. Spring and Summer. Be sure to remove all water sprouts and shoots that have originated from within 1 inch of old pruning cuts. Continue the stripping of shoots behind the leader, selection and propping of new laterals and 1- and 2-year-old scaffolds, and summer deshooting recommendations described earlier. The bottom, or 3-year-old, whorl may still need some additional spreading with larger (24- to 30- inch long) spreaders if the angle of the main lateral is less than a 40 to 50 degrees to the leader. Probably fewer than half of the limbs will need this fourth year of spreading. Fruit that is allowed to stay on the lower scaffolds will weight down and help spread these scaffolds further. Take care not to over crop. There should be a maximum of 1 fruit per 6 inches of limb, or 50 to 60 fruits per tree on trees that are allowed to fruit for the first time, usually during the fourth growing season. Defruit the entire leader and the top two whorls of laterals. Leave only a very few well-spaced fruit on the inner half of the bottom whorl of scaffold limbs. Four, Five and Six Year Old Trees Dormant Training. During February and March, dormant pruning of 4- to 5-year-old trees should begin by making the leader and scaffold selection cuts needed to continue training the fourth, fifth and sixth whorls of scaffold limbs. Older scaffold limbs must be headed back to make the tree conform to the inverted cone shape described earlier. Now that the tree has completed its first year of fruit production and has branched fruiting wood, the grower must start looking for dead and/or broken wood in the tree that may have resulted from over cropping or picking Fig. 7 This is a well pruned 2-year-old tree with limbs properly spread.
damage and for sharp or narrow crotch angles in the scaffold production wood that could result in future breakage. The vigil against water sprouts and regrowth around old pruning cuts must be continued, both during this period and throughout the mature bearing life of the tree. Special Considerations. Pruning in the fourth, fifth and sixth years represents the transition from training and limb selection to maintenance pruning. In the fourth year, give added attention to fruiting spur development and vigor. This is the main way a grower can judge if canopy density is open enough for good light penetration. (The other way is color development of red cultivars.) If spurs look vigorous, if flower initiation occurs, and if fruit is developed all the way through the canopy to the trunk, then a grower can be reasonably sure that proper tree density is being maintained. If, on the other hand, the grower sees a drop in spur development and/ or a lack of flowering and fruiting in the innermost portion of the tree, it is a warning that the grower must im mediately thin out the tree or risk loss of fruiting potential and fruit quality in the future. These are also the years to make decisions about crop load and fruit thinning to achieve continued annual production of good size fruit. Fig. 8 This is a mature bearing tree which has been properly trained to the central leader, inverted cone shape with mold-and-hold pruning. Stripping of the leader and spring shoot selection is still recommended but becomes somewhat less critical during this 4- to 6-year period. Summer deshooting becomes more important because of the need for greater attention to light relations within the tree as the tree moves toward full bearing. Continue spreading existing scaffold limbs for fruitfulness and good light penetration. It is equally important to maintain the inverted cone shape of the tree, both during this period and throughout the mature bearing years. The older and more mature trees become, the more attention is necessary to maintain tree shape. Mold and Hold Pruning. When the longest whorl of scaffold limbs of adjacent trees begins to touch or the limbs grow into the access lanes in the row middles, the grower must begin dormant pruning to contain the scaffold limbs in their allocated space. This is done by mold and hold pruning of the scaffold terminals. Mold and hold pruning (M&H) is distinct from any training or deshooting already described. It is, very simply, the cutting back of terminals to a shoot that is nearly the same size as the limb being cut, thus, molding or directing the vigor of the tip you cut off into the side shoot in order to hold the position and length of that particular limb. Depending on inrow and cross-row tree spacing, M&H pruning may be needed on at least the bottom whorl of scaffolds sometime during 4 to 6 years of age. M&H containment of scaffolds is usually required before the leader of the tree reaches maximum height and height containment begins. Maximum tree height is obtained (12-14 feet) and scaffold limb selection is usually completed after the sixth year of tree growth. At this time the inverted cone configuration of the tree is established providing lower scaffold limbs have filled their space or have been M&H contained. From this point on, when any scaffold limb, anywhere in the tree reaches the edge of the imaginary inverted cone, it must be M&H pruned to keep it in balance with the rest of the tree (Fig. 8). Height Containment. The leader of the tree is also pruned to contain it at the maximum desired height, but in a different manner from the M&H pruning used on scaffold limbs. At the same time the leader must also be used to expend, or sap off, as much excessive vegetative growth from the tree as possible. To accomplish this, the leader and any lateral shoots which originate within 1 foot of the top of the leader are tipped or stubbed. Remember, this stubbing is an invigorating or stimulatory process. All shoots in the top 1 foot of the leader are invigorated so they will grow freely, using up the tree s excess vigor and preventing excess growth in the lower portion. The term, sap-sucker leader has been given to this stubbed and invigorated upper 1 foot of a height controlled, bearing tree. This top 1 foot is allowed to grow freely throughout the season. During each
year s dormant pruning, these shoots are cut back to pruning to contain scaffold limb length. the original maximum height. Two or three new Look very closely at the internal area of the tree shoots are stubbed, leaving two to three buds to and ask these three questions: First, are any scaffolds repeat the sap sucker growth again next season. or secondary branches crowding each other? Second, are there any fine fruiting wood areas that are too crowded for good fruit color or might cause limb rub? Mature Bearing Apple Trees Third, are spurs healthy looking, or are they noticeably weaker the further in the tree you look? Special Considerations. A mature bearing apple Remove crowded scaffolds and side branches and do tree is one that has attained its maximum desired necessary thinning of fine wood to maintain spur height and width and in which the scaffold limb vigor and good light penetration. selection process has been completed. For a year or two after maximum height is reached and until all Canopy Density. During the growing season, scaffold limbs reach the length that fills in the inverted cone shape of the tree, it is necessary to tip while doing summer deshooting, and before or during harvest season, are the best times to make some decisions concerning critical tree density. Thus, the grow- and spread upper scaffold limbs. Dormant pruning of bearing trees can be started as soon as all the leaves er already knows that next winter I need to open the trees up or spur vigor and fruit color are okay so have been shed. The three most frequent mistakes made in pruning my tree density is on target. bearing trees are: (1) Letting the tree grow aimlessly Fruit color is the first evidence of excessive canopy in height. (2) Letting the scaffold limbs in the top half density. If spurs show weakness, pruning is already 1 of the tree get too long and shade the lower ones, losing the inverted cone shape. (3) Letting the interior of to 2 years late. If tree density is adjusted annually, productivity and fruit quality will be maximized. If the tree s fruiting wood get too dense. All three are tree density is uncontrolled, the tree will hollow out errors of poor management and lack of attention to or lose its spurs and fruiting potential in the interior annual pruning. We frequently hear growers say of the tree. There are three alternatives: Lose production; allow the tree to grow as it seeks new light and they cannot get around to pruning the whole orchard every year then those growers have too much spur formation; or do a major renovative pruning to orchard for their management and/or labor reestablish a productive tree. The latter will cost further production loss for 2 t0 4 years until new capabilities. fruiting wood develops inside the original tree Dormant Pruning. The best and easiest way to canopy. These alternatives are costly and unnecessary. streamline dormant pruning is to do summer deshooting as described earlier. Good dormant pruning In the past, researchers and growers have lacked of bearing trees begins with removal of all dead, information for a complete pruning program from broken and diseased wood, followed by removal of all planting through productive tree life. The central water sprouts and regrowth around old pruning cuts leader training and pruning program described has and elimination of any sharp crotch angles that have been carefully developed and thoroughly tested developed due to secondary branching in fruiting throughout the apple centers of the United States, including here in North Carolina. Any grower planting wood areas of the tree. This removes the obvious undesirable junk from the tree so the grower can see an orchard today has no excuse for letting tree what really needs attention for maintaining tree management get out of hand. Our North Carolina productivity. data document early fruiting, high yields and good After removing this unwanted or junk growth, fruit quality for all major varieties resulting from bring the tree height back to desired level by removing all new growth (not scaffold limbs) and water nent of this tree management package is summer de- this training and pruning system. A major compo- sprouts in the top 1 to 2 feet of the tree. Next cut the shooting that should be done each year. Deshooting leader back to its height last spring and leave two to keeps the fruit exposed to light during the summer three short shoots with two to three buds per shoot to and substantially reduces dormant pruning. Proper provide for next season s sap-sucker regrowth. Now fruit thinning is the other key horticultural management technique that must be practiced for good fruit the top is reestablished and the inverted cone shape can be redeveloped with the use of mold and hold size and color. Prepared by C. Richard Unrath, Extension Specialist Department of Horticultural Science Mountain Horticultural Crops Research Station Fletcher, NC 28732 J. D. Obermiller, Research Analyst Department of Horticultural Science Mountain Horticultural Crops Research Station Fletcher, NC 28732
Summary of Central Leader Training and Pruning Apple Trees Good tree management is the first and most basic step to good fruit production and efficient orchard management. Once the detailed training and pruning requirements and the reason for each have become completely familiar to the grower, the following summary check list can be used as an overview of needed training and pruning by tree age. ( Newly, planted \April r r lyr 4y 5 \KKKKK April \«KKKK March 2yr Late KKKKKKKFGMO March \KKKKKK Feb KKKKKKK Feb \KKKKKKKJan bearing Mature Nov to Dec * \KKKKKK Dormant Training and Pruning Time to start dormant pruning Head leader back to 24-26" Select 3 to 5 new scaffold limbs Tip scaffolds to form inverted cone shape Remove dead or broken limbs Remove wood with sharp crotch angles Remove riser shoots and growth on old cuts Thin fruiting wood for light and spur vigor Prune top to hold tree height Mold and hold prune sides of tree to maintain in space allocated Training at 1 to 2 of growth Strip new shoots 4-5 below new leader Training at 4-6" of growth Select 4 to 6 lateral shoots for scaffold limbs and prop out «K \\ KX RX\K 32R * Maintain sap-sucker leader. ** Defruit part of tree only. \/ Prop older scaffold limbs K Defruit all or part of tree K K \/ \/ \/ Thin fruit May, June and/or July \/ \/ \/ x/ \/ \/ \/ Remove water sprouts (summer deshooting) This publication is included in the N. C. Apple Production Manual. To obtain other bulletins in this series, contact the Department of Horticultural Science, North Carolina State University, Box 5216, Raleigh, NC. 27650. Published by THE NORTH CAROLINA AGRICULTURAL EXTENSION SERVICE North Carolina State University at Raleigh, North Carolina Agricultural and Technical State University at Greensboro, and the U. S. Department of Agriculture, Cooperating. State University Station, Raleigh, N. 0., Chester D. Black, Director. Distributed in furtherance of the Acts of Congress of May 8 and June 30, 1914. The North Carolina Agricultural Extension Service offers its programs to all eligible persons regardless of race, color, or national origin, and is an equal opportunity employer. l-84-1.5m Price 50c AG307