Allen Wilson from columbian said that Fruit trees should be pruned every year. The best time to prune is late winter or early spring before they start to grow. Pruning fruit trees is quite different from pruning shade and other ornamental trees.
The goal is to produce good yields of high quality fruit that is relatively easy to pick. Most fruit trees are grafted onto semidwarf root stocks. Semidwarf trees can be kept in a size range of 10 to 12 feet with regular yearly pruning.
Without yearly pruning they will often grow twice that height or more. Most of the fruit is then not within easy reach and must be harvested with a ladder. Trees on true dwarf root stocks can be kept even shorter.