Frequently, the orchardist desires to renovate neglected, aging apple trees. Although the following description is the procedure for pruning trees in this condition, for several reasons it is generally more logical to remove the trees or to keep them for shade. First, the care of aged, high-topped apple trees is laborious and expensive. Second, the fruit quality is generally poorer on older trees than on young, well grown trees. Also, the trees may not be the desired varieties. Finally, many of the older varieties have a strong tendency to bear heavy crops only every other year.
Pruning the aging, high-topped apple tree is largely a job of renovation, followed by renewal of fruiting wood. The pruning must be moderate and spread over a two- or three-year period to avoid excessive growth and/or injury to large limbs from sudden over-exposure to sunlight. Such pruning consists of gradually lowering tree height to 18 feet or less, removal of surplus scaffold limbs, and the elimination of weak wood.
The first step in renovation is to remove all dead and broken branches and branch stubs. Once this job is accomplished, pause and look at the tree. The interior and outer portions of the tree will be filled with many small branches that either droop towards the ground or crowd one another. The tree is probably so dense, it is difficult to walk into its center without pushing aside branches. Now note that there are an excessive number of large branches arising from the trunk and main leader; six to eight main scaffold branches are sufficient.
Remove, by pruning at point of origin on the trunk or central leader, several of the large branches that cause crowding in the lower two-thirds of the tree. A chain saw may be used for this job. The tree now has been "opened up" considerably. This should allow improved light conditions during the growing season and make thorough spray applications possible. Probably the number of scaffold limbs is still excessive, but this condition can be gradually eliminated over the next year or two.
Removal of Weak Wood
The next step is pruning out drooping branches and much of the bushiness caused by the excessive number of smaller, secondary branches. Then "thin out" the remaining secondary branches by removing a third of them. This procedure further enhances penetration of sunlight and spray materials.
Lowering Tree Height
The next step in the renovation procedure is lowering tree height. To reduce height, remove tall, upright branches entirely, or cut them back to well-placed strong lateral branches that extend horizontally below the height of 18 feet. A chain saw again is handy because these cuts generally involve removing limbs 6 inches or more in diameter. If a tree has several of these tall branches, thin them out over a two- or three-year period.
Cut back branches in the upper tow-thirds of the tree to produce a pyramidal or "Christmas tree" shape.
Lowering tree height requires follow-up pruning year after year to take advantage of newly developing fruiting wood and to avoid a return to the previous problem shape. However, the lowering of tall trees introduces the annual nuisance of water sprouts which develop near the larger pruning wounds and on the trunks. Those arising on the trunk or in the inner two-thirds of the lower limbs are likely to be of no value and should be removed. Water sprouts will also arise in great abundance on the upper side of the limbs in the upper third of the tree the year following lowering of height. These should be thinned out to a distance of about 2 feet, leaving those that bend towards the outside of the tree, and heading back others to force lateral branching. The remaining water sprouts may develop fruiting wood the following season, but new water sprouts will appear and must be removed.
Written by: Paul Lopes