Importance of Annual Pruning
Annual pruning is important throughout the life of the tree. While the tree is young annual pruning is needed to develop the desired tree structure. As the tree grows older, annual pruning is necessary to keep the tree productive and to prevent it from becoming too large and too dense. Pruning stimulates the growth of the above-ground portion of the tree that is left after pruning, but this portion of the tree will be less than that of an unpruned tree. Furthermore, severe pruning of young trees tends to keep them from being productive and may delay the start of bearing. Thus the pruning of young trees should be moderate, the objective being to develop a well-shaped, structurally strong tree.
The severity of annual pruning suggested for trees varies among the various types of fruits.
Most severe annual pruning needed:
- Japanese-type Plums
- Sour Cherries
- European-type Plums
Less severe annual pruning needed:
- Sweet Cherries
When to Prune
- Light pruning may be done any time of the year, but heavy pruning usually should be limited to the latter part of the dormant season, preferably from February 1 to March 15 in the southern half of Illinois and from February 15 to April 1 in the northern half.
- Pruning before February 1 in southern Illinois and February 15 in northern Illinois may increase the danger of cold injury to the tree. If pruning must be started before the dates suggested here, start on older apple trees requiring light to moderate pruning.
- Wait until late winter or early spring to prune young trees. Peach and nectarine trees are exceptions; pruning wounds heal more rapidly and with less chance of infection if these trees are pruned just before bloom or during bloom.
Summer pruning of apple trees is becoming more popular because of the increasing interest in small-sized apple trees.
- Pruning during the dormant season stimulates new top growth because more energy is available to the remaining parts of the tree.
- Pruning in August, in contrast, has a dwarfing effect on the growth of apple trees bearing a crop of fruits because the number of leaves is reduced, resulting in decreased food production.
- Vigorous shoots—new growth that is more than 12 inches long—can be re- moved.
- Apple growers have found summer pruning to be especially helpful in keeping dwarf and semidwarf apple trees at a desired size.
- Summer pruning should be used in conjunction with dormant pruning rather than as a substitute for it.
Essentially, moderate to heavy dormant pruning is replaced by light summer pruning and light dormant pruning.
Removal of water sprouts and suckers during May, June, and July is preferred over cutting them out during the dormant season. Water sprouts invite insect and mite pests, clog and shade the interior of the trees, and make the trees harder to spray. Though all types of fruit trees may be pruned lightly during the summer, summer pruning is most useful on apples and peaches.
Make pruning cuts at the outer edge of the collar (Figure N-19.). Leave the collar intact, but do not leave stubs. If latent (non-growing) buds are present on the stub, they may start growing and fill up the open area. If no latent buds are present, the bark on the stub usually dies; leaving the wood to rot before healing can begin.
The major exceptions to these recommendations on making collar cuts are certain cuts on young spur- type apple trees. If more than half of the bark area of the branch or trunk will be removed by a collar pruning cut, growth may be severely retarded. In this case, a stub can be left for 1 year. However, remove any shoots starting to grow from it. After 1 year remove the stub with a collar cut.
Treating Pruning Wounds
It is not necessary to treat pruning wounds. Treating the wounds may retard the healing process.
General Pruning Rules
The following general pruning rules are applicable to all fruit trees.
- Remove dead and broken branches.
- Remove diseased branches, or the diseased parts of branches.
- Remove water sprouts. These are rapidly growing young shoots arising from the trunk or scaffold branches. They grow straight upward, frequently without branching.
- Remove suckers. These are shoots arising from the roots or from the trunk at or below the ground line.
- Eliminate competition between branches. If one branch grows into another branch or rubs another branch, remove the least desirable branch.
- Eliminate V branching. If two branches of about equal size form a narrow V, eliminate one.
- Remove weak, slow-growing, drooping nonproductive branches.
- Remove branches or parts of branches that touch the ground.
- Avoid selecting main branches growing toward the direction of prevailing summer winds. Illinois frequently has high summer winds. The prevailing direction of these winds is from the southwest. When trees are in full leaf, winds may distort the tree shape because branches growing toward the prevailing wind tend to be blown back into the center of the tree.
- The first 5 years the tree is in the orchard, prune only enough to properly train the tree. Remember that pruning is really a dwarfing process, although some parts of the plant may be selectively increased. Severe pruning can delay the development of bearing wood and thus retard the onset of bearing. The main object of training young trees is to develop the desired framework and bring the trees into production as quickly as possible.
Branch Spreaders and Tiedown Spreading
Branch spreaders are helpful in training young trees to the central leader system. Stiff wire, metal rods, or welding rods sharpened at each end make satisfactory branch spreaders. Boards with a nail in each end, the head of which is sharpened to a point, also are satisfactory. Lengths from 5 to 36 inches are suggested, depending on the size and strength of the branch.
The tie down method of spreading branches is especially useful for home fruit growers. Tied downs can be placed farther out on the branches than spreaders, and branches can be pulled laterally to the desired location. Upper branches can be tied to the lower branches. When the tie down method is used in conjunction with mulch culture, the stakes do not interfere with mowing,