Goals in training and pruning fruit trees are usually different from those in pruning ornamentals. Maximum fruit production and maintaining a size that allows for quick picking are usually more important than an attractive shape. Each type of fruit, however, has characteristics that require slightly different approaches. Understanding the growth and fruiting pattern of your tree is essential.
Pruning is the method most often used to shape a fruit tree, but occasionally branches may be pulled in the desired direction using ropes. These are well-padded at the points where they touch the branch to avoid injury to the bark. Spreaders, pieces of wood that are padded at both ends, can be placed to push a branch into a better position, and weights may be tied to a branch to pull it down. In espaliering trees, which involves training them to lie flat against a wall or trellis, branches are often bent and tied into position using plastic tape.
Maximum production of fruit while maintaining the health of the tree is achieved by creating a strong framework of branches with enough space between them to allow sunlight to reach the center of the tree. Pruning out dead wood and crossed branches in part of this process. Apple trees bear fruit on short spurs that live for many years, so training is done to maximize these spurs. Peaches, on the other hand, bear mainly on one-year-old wood and are pruned more severely to encourage new shoots.
Begin training a fruit tree immediately after planting. Know the best shape of the tree you have, imagine the desired branches and either make cuts that will encourage those branches or take existing branches and tie them in the direction you want them to grow. Spring pruning is common, but in mild-winter areas, fall is also a good time to remove branches. Taking unwanted shoots off during late spring and summer, before they lengthen, is also helpful.
Proper training gives a fruit tree strong branches capable of supporting a heavy crop of fruit. Apples and pears, for instance, need side branches with a 45-degree crotch that will not split as a narrow crotch would. Fruiting spurs are also more likely to form on horizontal rather than vertical branches. Low, well-spaced branches keeps fruit within picking distance. Even dwarfing rootstocks may not produce a backyard-sized tree without additional training. Espalier trees, grown flat against a framework, produce generous crops of fruit without taking up much room.
Knowing what a well-pruned apple, peach or cherry tree looks like will help you visualize the best way to train your tree. Visiting an orchard nearby can be very helpful. If that's not possible, finding a diagram in a book may be a good substitute.
Keep a good balance between fruit and vegetative growth--this is important. Excessively vigorous trees may need to be held back in some manner so their energy can be channeled into fruit production rather than leaves and shoots. This can be done by avoiding nitrogen fertilizer, withholding water occasionally or removing overly energetic, non-fruiting sprouts early in the season.