Question
Jim, five years ago we had four beautiful young maple trees installed. They are each about 15 feet tall. We have had the catepillars pretty bad the last couple of years and the soil up here is very rocky and gravely. Last summer i noticed the tops of these trees didnt have leaves and this spring the two end trees looked like they barely had leaves. I also noticed on all the trees that they have deep cankers on their trunks down low. I had a local tree company come and inject liquid feed which seems to have helped the two strongest trees but the other two dont look good. Also it looks to me that the two good trees have good sized cankers. Can these trees survive the cankers? Would it be a mistake to replace the two dying trees with new maples?

Answer
They can survive the cankers but the canker may weaken the trunk causing it to break off during a wind storm. I would fertilize the trees with 10-10-10 fertilizer at the rate of 1 lb per inch of trunk diameter scattered around the tree and watered in good. do this now and again in the Fall. This will help the overall health of the tree. Liquid fertilize injected in the ground around the tree will also work.