Here’s some links to sites explaining proper pruning of fruit trees.

http://www.ces.ncsu.edu/depts/hort/hil/ag29.html

 http://www.weekendgardener.net/how-to/prune-apple-trees.htm

Neglected trees

Many people will purchase a house where an apple tree was planted on the property several years ago. Often, the previous owners did not take the time to properly prune the tree. The tree has become bushy and weak and will produce very poor quality apples. Such a tree requires extensive corrective pruning.

The main objective in pruning such a tree is to try to open up the interior to allow good light penetration.

The first step is to remove all the upright, vigorous growing shoots at their base that are shading the interior. As with the young apple trees, it is necessary to select 3 to 5 lower scaffold branches with good crotch angles and spaced around the tree. Limbs with poor angles, and excess scaffold limbs, should be removed at their base. In some cases it is advisable to spread the corrective pruning over two to three seasons. When severe pruning is done in the winter, the trees should not be fertilized that spring.