Once the trees begin to bear fruit and no later than when they reach their fifth winter, discontinue heading back the new terminals. Pruning for the rest of the life of the tree will be done to maintain the conical structure. Remove vigorous upright or downward-growing shoots. A good image to guide your pruning is to try to create two-dimensional scaffold branches. This means the branches will have a single terminal point and will spread out in a triangle back into the center of the tree but will not have any shoots growing up or down (Figure 4.7). Try to retain only shoots that are horizontal. Periodically thin out the branching structure to allow adequate light to penetrate the interior and lower portions of the tree.
Always maintain the central leader as the highest point on the tree. The ends of the primary and secondary scaffolds should be kept below the top of the tree. Prune the trees every year in late winter (February or March).
You can view a copy of the slide set "Pruning and Training Fruit Trees" to help assist you in your pruning.