The Right Place to Trim
The biggest pruning mistakes we see are branches cut in the wrong place. Most amateurs tend to leave too much of a stub when they remove a branch. The problem is, once this stub dies off, it creates a perfect entry point for insects and disease pathogens.
Trees don’t regenerate tissue the same way humans do. While our skin acts to replace itself, trees grow new tissue around their wounds in a process known as compartmentalization. If a tree can compartmentalize an old pruning wound, it has a much better chance of survival. Also, efforts should be made not to create wounds on tree trunks with lawn mowers and other machinery. Destructive fungi are opportunists!
Trees have a natural defense system built into the swollen area known as the collar, where the branch meets the trunk. It is important to make a flush cut close to the trunk without removing the collar. The proper cut is made just beyond the collar, not leaving a stub, but leaving the swollen area intact.
DON'T leave a stub, but DO leave the collar at the base of a branch, since a tree has natural defenses there. Always make clean cuts.
The first step in removing a branch is getting the weight off: