Answer: If the fruit type or variety appears to be something you wish to keep, you can take steps to restore such fruit as apples, persimmons and pears. Other types, including peaches and plums tend to a bit shorter lived trees and may not be worth trying to restore and save. Also, some of the new varieties of fruit now available offer desirable improvements such as disease resistance which may make it better to start over with a new tree.
If you decide to restore an old tree, I'd suggest the following advice gleaned from a Georgia Extension Service publication. Start by doing a severe pruning to remove dead, diseased, tangled and broken branches. The main objective in pruning such a tree is to try and open up the interior to allow good light penetration. The first step is to remove all the upright, vigorous growing shoots at their base that are shading the interior.
Limbs with poor angles, and excess scaffold limbs, should then be removed at their base. In some cases it is advisable to spread the corrective pruning over two to three seasons. The next year, it will be necessary to remove more limbs. Most of the cuts should be thinning types; that is, the wood was removed to its base or point of origin. When making these thinning cuts, make sure the cuts are made flush along another limb. The remaining limbs can be pruned back by one-fourth of their length to a side limb if it is desired to stiffen them. If you don't cut them back, the limbs may bend and/or break under a heavy crop load.
Clean up under the trees to remove brush or tall grass and place a thick mulch on the soil surface beneath the branch spread to reduce weed competition.
When the tree begins to regrow in spring, make sure and thin out the multitude of sprouts, leaving only a few (which are oriented in a desirable direction) to remake the new branching system of the tree. Fertilizer may be useful but be sparing as the pruning and weed control will be quite invigorating on its own.
Thanks for the question and good luck with your trees!
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