Question
We have a crab apple tree that has the trunk full of little holes.  We had a piece of plastic drain pipe around the trunk to protect it from mice during the winter and when we took that off we noticed the small holes.  The tree produced many apples this year but we are concerned we may lose it due to the damage of the trunk.  Is there anything we can do to save it such as putting pine tar on it?  Any advice will be appreciated.  Thank You.

Answer
May be borers. I would spray the trunk with an insecticide called Merit. This will kill the borers. Then fertilize the tree this fall and again in the spring with 10-10-10 fertilizer at a rate of 1 lb per inch of tree diameter. Spread this fertilizer around the tree and water in. I would not put anything on the holes this may slow the healing process.