Question
Because I am out of town a lot, I have missed the little culprits who have been swinging on the lower branches of my approximately 14-year-old Maple tree.  My neighbor has repeatedly told the boys to get out of my yard, but the branches are now about a foot off the ground, so low that my yard-man cannot get the mower under them.  I know I am not suppose to trim these branches but what should I do in the meantime about these poor pitiful hanging branches.  This is the only tree I have for shade on the west side of my house, and I would be devastated if I lost it.  Please help!

Answer
You can prune the lower limbs off at the trunk on maple. Maples are known as "bleeders".  This means they will drip from pruning wounds if they are cut in seasons when the leaves are off, but they aren't fully dormant.   Recent university research has shown that "bleeding" doesn't really hurt the tree.  However, if you want to prune without bleeding, a Maple must be pruned when it is fully dormant; Mid-Winter -or-  mid to late Summer when it is fully leafed out.

The biggest pruning mistake 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 human beings 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.


The first step in removing a branch is getting the weight off:

Go out a foot or two from the trunk and first make an undercut 1/3 of the way up from the bottom of the branch.   If you go too far, your saw will get pinched.
Then make your second cut all the way through the branch from the top side of the branch, just an inch or two outward from your first cut.
The branch should then fall away without tearing bark back to the trunk.  Maples always want to tear.


Here is a diagram of the pruning cuts.

http://www.ci.albany.or.us/parks/urbanforestry/img/pruningdiag_l.jpg