Now is the best time to prune many of your trees and shrubs, including fruit trees. Pruning of fruit trees is done to improve fruit quality, develop a strong plant, facilitate harvest, and control the size/shape of the plant. According to Rhonda Ferree, Horticulture Educator with University of Illinois Extension, unpruned trees and plants are difficult to maintain, produce small fruit and are much more likely to suffer disease problems.
If you have new fruit trees, begin the practice of pruning them each year. For the first few years after planting, the primary purpose is to develop a strong permanent framework that will produce good fruit yields over an extended period of time. If you have an old tree that has not been pruned in quite some time, it can be pruned, but do it slowly over three years.
Rhonda says, "When I prune any woody plant, I follow these steps." "First, begin by removing the 3 D's: dead, damaged, and diseased wood". "Second, remove water sprouts (branches that go straight up), suckers (branches at the base of the trunk), crossing limbs, and girdling roots." "Third, work to create a strong structure." "Finally, thin out more if needed." "After each step, I walk away from the plant and look at it." "I may be done pruning, or I may move on to the next step."
Although you can follow these steps with fruits trees, fruit tree pruning is entirely different from pruning other trees. With fruit trees we make many more cuts and sometimes drastically cut the tree, leaving stubs that we never do with other trees. There are two primary methods of pruning fruit trees: central leader and open center.
The central leader system is used for apples, pears, and some cherry trees. Basically, you will leave a central, upright stem and work on outside branches to create scaffold branches about every 18 inches along the trunk of the central leader. Yearly pruning is done to maintain shape and develop strong scaffold branches, to remove excess growth, and to limit the amount of fruit that forms. Apple fruit will grow on 2-year-old branches.
The open center system is used for some cherries, peaches, and apricots. This system opens up the center of the tree and allows for better air circulation and light penetration within the branches. This pruning system develops two to four, preferably three, primary scaffolds arising near each other on the trunk. All primary scaffolds are pruned to form about equally spaced around the tree. From those main branches, a second set of scaffolds is designed that fan out and extend further up the tree, giving it a vaselike structure. Peaches typically bear fruit on 1-year-old wood, so be careful not to prune away all the fruit buds.
Learn more about growing your own fruit at http://extension.illinois.edu/fruit.