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Ch. 8, pp. 17 - 23

[Pruning: fruit trees | other | small fruit ]

When pruning fruit trees for best production, remember these basic concepts:
(1) Pruning invigorates and results in strong growth close to the pruning cut. Pruning reduces the number of shoots so remaining shoots are stimulated. However, total shoot growth and size of the limb is reduced.
(2) Two types of pruning cuts are heading back and thinning out. Heading is cutting off part of a shoot or branch apical dominance and removes stimulates branching and stiffens the limb. Thinning cuts remove the entire shoot or branch at its junction with a lateral, scaffold, or trunk. Thinning cuts are less invigorating, improve light penetration, and can redirect the limb.
(3) Limb position affects vigor and fruitfulness. Vertical or upright branches, typical in the tops of trees, produce the longest shoots near the end of the limb and tend to be excessively vigorous and not very fruitful. Fruit are often of poor quality and subject to limb rub. Limbs growing slightly above horizontal are more apt to develop a uniform distribution of vigor and fruitfulness. Light distribution tends to be even, and because fruit hang along the branch, they are less prone to limb rub. Limbs growing below horizontal tend to develop suckers along the upper surface. Excess sucker growth will result in shading. Hangers, or limbs developing on the underside of branches or scaffolds, are heavily shaded and low in vigor. Fruit developing on such wood is of poor size and color.
Training and Pruning Apple TreesTop

Non-Bearing Apple Trees
The objectives of training, directing, or modifying growth into a desired form include early fruit production, development of an optimum tree structure for support of future crops, and optimum fruit quality conditions. These objectives can be met by maintaining a proper balance between vegetative and potential fruiting wood. Excess shoot growth will delay the onset of fruiting. Thus, excess pruning of young, non-bearing trees will delay the beginning of fruit production in the life of that tree. Training should be emphasized in the development of trees, with pruning used as a tool in the training process to redirect limbs, stimulate branching when desired, or to remove growth that is in an undesirable location. Pruning should not be used to invigorate growth in an attempt to compensate for poor fertilization, poor weed control, or drought conditions.
Apple Tree
Future pruning of an apple tree is greatly affected by early training. Much of the pruning of young, bearing trees is the result of errors made in training in the early life of the tree. Thus, it is imperative that training begin early. A delay for the first 3 to 4 years will result in a poorly-developed, weak tree. Correction of such a problem, usually with heavy pruning, will only further delay and decrease fruit production.
An integral part of a tree-training program is limb-spreading. Limb orientation affects vigor in various ways. An upright or vertical limb produces the longest shoots near the apex and tends to exhibit high vegetative vigor. This is known as apical dominance. Often, fruit hang down against the limb and are subject to rub. As limbs are oriented away from vertical, they exhibit reduced vigor of shoots near the apex, more uniform branching along the shoot, and favor development of fruiting spurs. Fruit hang along the limb and are less prone to rub. A limb orientation around 60° from vertical is desired. However, horizontal orientation of limbs results in the development of vigorous water sprouts along the upper surface of the limb, at the expense of potential fruiting spurs.
Bark Inclusion
Thus, correct limb-spreading (near 60° from vertical) can be used to develop a proper balance between vegetative and fruiting growth. Limb-spreading should begin early, as many cultivars, such as Red Delicious (particularly spur-types), naturally develop narrow crotch angles. If these narrow crotch angles are not widened (greater than 35°), a situation can quickly develop in which bark is trapped between the trunk and scaffold limb (bark inclusion). This bark inclusion prevents layers of annual wood from growing together and creates the potential for splitting. If these narrow crotch angles with bark inclusions are allowed to develop, later attempts at limb-spreading may result in splitting of the crotch. Two objectives exist for limb-spreading: 1) development of a strong, wide crotch angle (greater than 35°) free of bark inclusion and 2) limb orientation at 60 degrees from vertical to balance vegetative and fruiting growth. To derive the benefits of limb-spreading, the crotch must be physically strong, to undergo spreading without splitting.
Wooden Spreader
Poor pruning practices are not a wise substitute for proper limb-spreading in the training of upright scaffolds. Improper pruning cuts will not change the crotch angle, improve limb position, or aid in the control of vegetative vigor. Scaffold limbs should be spread and lower laterals removed if necessary.
At Planting
Trees must be pruned at planting for several reasons. The top of the tree must be brought into balance with the root system, which is usually damaged in the nursery digging operation. Pruning forces the growth of laterals from which future scaffolds will be selected.
Head spur types and semi-dwarfs to a height of 30 to 35 inches. Standards are headed to 40 inches. If feathered (branched) trees are planted, they should be headed to a strong bud to stimulate growth of the central leader.
Feathers desirably located can be retained as scaffolds and should be headed. Undesirable feathers should be removed.
First Growing Season
Scaffold selection can begin in the early summer, especially on cultivards developing narrow crotch angles. Shoots developing below the lowest desired scaffold should be removed. Generally, in the first year, 4 to 6 good scaffolds, 5 being ideal, can be selected that are evenly distributed and not directly above one another.
The vertical spacing between scaffolds can vary from 3 inches to 12 inches depending on the ultimate size of the tree. Limbs with crotch angles less than 35° should be spread or removed. Hardwood toothpicks, or clothespins can be used if training is done in early summer while shoots are soft. Short pieces of #9 wire can also be used.
Shoots undesirably located should be completely removed at this time.
First Year
First Year

Second Year
Second Year
First Year Dormant Season
Select shoots to be retained as scaffolds if this was not done earlier. Selected scaffolds to be spread or tied in the spring before any pruning is done. Spreading changes the shape of the tree and may influence pruning decisions. Remove shoots that were not selected as scaffolds. The central leader should be headed to maintain dominance if needed and induce branching. This is done 3 to 5 inches above the point where the next tier of scaffolds is desired. Refrain from heading scaffolds unless they need to be shortened or stiffened. Generally a year-old shoot naturally branches in the season after development. Spreading that scaffold will encourage uniform branching. However, a scaffold will often exhibit excess vigor and upset the balance of the tree. Heading can also be used to encourage growth and branching on spur types.
Second Growing Season
Limbs not previously trained can be easily weighted down, spread, or tied early in the growing season. The new tier scaffold limbs can be selected and trained at this time if the tree is growing on a standard semi-dwarf rootstock. These should be well-spaced without shading the lower scaffolds.
Second Year Dormant Season
Some of the scaffolds that were selected and spread in the first year may turn up and resume vertical growth. Longer spreaders, weights, and/or tie downs can be used to spread the limbs back to the desired orientation. The smaller spreaders can be moved further up into the tree. Again, scaffolds should be spread before pruning. The central leader should be headed again to maintain vigor and stimulate branching if needed.
Succeeding Years
Continue training and pruning following the previously discussed principles of central leader dominance and proper scaffold selection and training. Scaffolds should be maintained in a 35° to 60° orientation. A conical tree shape should be maintained. Thus, the upper scaffold should be shorter than the scaffold below it. After the third year, upper scaffolds can be shortened with the use of thinning cuts to remove shoots at the junction with a lateral scaffold or trunk. Thinning cuts are less invigorating than heading cuts, improve light penetration, and can redirect the limb.
Remove crossing branches and vigorous water sprouts. Shoots growing up into and toward the center of the tree should be removed.
Once the desired tree height is reached, the tree can be maintained by annually cutting back to a weak lateral on the central leader. This will maintain vigor in the top center of the tree while maintaining desired tree height.
Bearing Apple TreesTop

When pruning is underway, older, bearing trees should be pruned first. Young, non-bearing apple trees and stone fruits can be pruned later to minimize chances of winter injury.
The balance between vegetative and fruiting growth is influenced by the crop load, fertilization, and pruning. Fruiting may be poor because vigor is too high or too low. Excessive vigor can be the result of inadequate fertilization, no pruning, excessive cropping, or shading of fruiting wood. Good fruiting wood requires moderate vigor and exposure to good light levels.
Light is the source of energy that produces the crop. Bearing wood that is shaded is low in vigor and produces small, poorly colored fruits. Good light exposure is necessary for the development of flower buds as well as optimum size, color, and sugar content of the fruit. Studies have shown that a typical tree canopy is composed of different layers or zones in respect to light exposure. As shown, an outside zone of leaves and fruit receives a high proportion of direct light and light levels above those required for good growth and fruiting; a second zone receives adequate light exposure; and a third, inner zone receives inadequate light exposure and is unproductive.

Next Year's Cut
The relative proportion of these zones in a tree is influenced by tree size and shape. As tree size increases, the percentage of the tree that is shaded and unproductive (third zone) increases. Trees that have wide tops and narrow bottoms, an inverted pyramid shape, also have a high percentage of shaded areas in the tree canopy. Trees should be cone-shaped, or larger at the bottom than the top, to maximize adequate light exposure. Good light exposure in the tree canopy can also be maintained by a good pruning program. Ideally, pruning should remove unproductive wood and develop a uniform distribution of vigor and light exposure throughout the tree. Proper pruning can also help to maintain desired tree size and shape.
Pruning should be done on a regular basis and consist of moderate cuts made throughout the tree to distribute vigor and provide good light penetration. Heading cuts should only be used where branching is desired or in areas where vigor is low. Drooping or low-hanging branches should be removed or pruned to a lateral that is positioned above horizontal. Remove crossing, dead, diseased, parallel, or damaged limbs. Water sprouts should be removed unless one is needed for the development of new bearing surface. Water sprouts can be easily removed by hand as they develop in the summer.
Without regular annual pruning, trees often become overly thick, and irregular or alternate bearing may occur. Spray penetration is reduced, and pest problems, such as scale, may develop in the dense areas of the tree. With this type of tree, make many thinning cuts throughout the tree with emphasis on the upper, outer portions of the tree. This will open up areas into the tree canopy as well as re-establish good tree shape.
Avoid bench cuts to outward-growing limbs unless necessary. Such cuts result in weak limbs and an umbrella shape that creates a sucker problem. Remove no more than 2 large limbs or 30% of the tree limbs per year. If large amounts of pruning are required, it should be spread over a 2 to 3 year period. In addition, such pruning should be preceded and followed for 1 to 2 years by a reduction or elimination of nitrogen application, depending on soil type, variety, and grower experience.
The excess vigor that can result from severe pruning can decrease fruit quality. The effect is much the same as from excessive nitrogen application and may include excessively large, poorly colored, soft apples which will not store well. Vegetative growth competes with fruit for calcium; thus, under conditions of excessive vigor, cork spot may develop.
Hedging and topping should only be used to maintain tree size when trees are at or near desired size. Such pruning is often used in an attempt to reduce tree size. Misuse can result in a disruption of vigor and loss of yield which may take several years to control. Hedging and topping (mainly heading cuts), especially of one-year shoots, induce masses of shoots close to the plane where cutting takes place. This localized invigoration of shoots can shade and weaken inner areas of the tree.

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