Thinning to let more light through to the grass will do the same thing cause tree stress. Proper pruning dosage is limited to deadwood, stubs, weakly attached branches, and correction of structural problems. Myth 4 Tree wounds need paints or sealers to aid healing. This actually contains two myths. Trees need help from people to do this.
Healing means to replace damaged tissue with new tissue.
Trees seal their wounds by building walls around them and adding new tissue over them. Trees prevent the advance of decay with internal barriers. The branch collar is a built-in protection zone within tree branches. Improper pruning cuts remove the branch collar and allow decay to advance in the tree. It is best to use the natural defenses of the tree and get out of the way.