For optimum health and tree-size control, prune apple trees in the summer. Growers control the shape and size of the tree with summer pruning. Trees with proper training and regular pruning yield fruit for longer periods of time, advises the North Carolina State University Cooperative Extension. With proper pruning, apple trees develop sturdy branches providing fruit weight support. The potential of weak limbs, tree diseases and branch breakage reduces due to summer pruning. Maturely trained trees do not require this type of pruning.
Remove all ripe or old and rotting fruit from the apple tree just prior to pruning. Discard the old fruit or take it indoors.
Tie a small piece of cloth or string to new and smaller branches growing in straight-upright shoots.
Stand back from the apple tree and examine the markers. Only a quarter of the tree or less should be pruned at one time. Remove markers from smaller branches, if more than a quarter of the tree has limb markers. Removing more than a quarter of the apple tree limbs creates too much stress and can kill the tree.
Spray the front and back of the of the pruning shear blades with a light mist of disinfectant spray. This will sterilize the pruning shears and prevent spreading disease throughout the apple tree.
Place the pruning shears at a 45-degree angle on the first marked branch a quarter-inch from the main supporting branch or tree trunk. Close the pruning shears quickly to make a sharp, clean cut. Repeat with all the marked branches.
Pick up the prune branches and shred for compost or dispose of properly.
Water the tree with 2 inches of water. Check the tree base and replace mulch as needed. Make certain no mulch is touching the trunk. Clean up any fruit on the ground. Remove any weeds under the tree's drip line.