When pruning is necessary, prune dead and dying branches properly to help the tree heal its branch wounds faster and to reduce the chances for infection that could lead to decay. Using a proper pruning cut will help the tree, while improper pruning only causes the tree more trouble. Serious trouble can result from improper pruning unless you these steps as illustrated:
1. Partially undercut the branch
Use and uppercut to remove branch
3. Flush cut the stub
You should always remove a limb using the above three steps. In effect you are making three cuts. You remove the limbs weight in step one and two and remove the stub in step three.
Prevent Decay by Proper Stub Pruning
Many microorganisms use old dead stubs as springboards into the trunk. Pruning dead limb stubs properly is extremely important and prevents major decay and tree trunk rot. The dead limb prune must be done next to but not in the living wood collar that surrounds the stub according to the USFS publication AIB-387. I have found that you can take just a bit of the collar but don't overdo it.
When a tree top is broken, prune out the broken portion of the top but leave a vigorous branch near the broken top to use as a new leader. When pruned properly, the tree will heal its wound faster and the likelihood of decay developing decreases. If decay does develop, it is usually limited to where the old leader was pruned.
So what branches and limbs need to be removed? Sometimes it is not so easy to determine a living limb or branch, especially during dormancy. A tried and true gardener's trick will help test the vigor of a branch to see if pruning might be necessary. A great way plant health and vigor can be determined by using this illustrated "bark scratch test".