1) Fruit and nut trees are pruned and trained to develop a strong structure that can support heavy crops without breaking. Pruning is also needed to maintain size, remove undesirable growth, and stimulate flowering and fruiting.
2) It is important to understand tree structures like the central leader, scaffold branches, and branch attachment angles. Watersprouts, suckers, and dead wood should be removed. Trees compartmentalize wounds to prevent decay.
3) Fruit trees are typically pruned using either a central leader method that forms a pyramid shape, or an open center method that forms a vase shape. The central leader method maintains a central trunk with spiral scaffold branches.