Thin all varieties to permit thorough spraying and the entrance of sunlight and air. Where it is desired to reduce the height of tall trees, cut the leader branches back moderately to a well-developed horizontal lateral. Prune the lower branches of broadheaded or drooping varieties to ascending laterals. Varieties that tend to produce numerous twiggy, lateral growth should have some of this growth removed to prevent overcrowding. Make close, clean cuts.
Stubs encourage decay and canker, thus forming a source of injury to the parent branch or trunk.
Very heavy pruning is likely to upset the balance between wood growth and fruitfulness, and generally should be avoided. Trees that are given some attention each spring are more easily kept in good condition than trees that are pruned irregularly. Prune that part of the tree where more growth is required. This is particularly important with old trees. New growth will be stimulated only in those parts of the tree that were pruned.