In the first two years especially, cut back vigorous varieties as often as necessary. Do not allow any variety to dominate and shade out the others. Second year pruning is the same as the first year. Cut back new growth by half in spring and late summer. In the third year choose a height and don't let the tree get any taller.
Tree height is the decision of the pruner.
When there are vigorous shoots above the chosen height, cut back or remove them. Remove broken limbs. Remove diseased limbs well below the signs of disease. The smaller one, two and three year old branches that bear fruit should have at least six inches of free space all around. This means that where two branches begin close together and grow in the same direction, one should be removed.