Hole In The Trunk Of My Maple Tree

Q: I have a beautiful maple tree in my front yard. There is a big hole the trunk where a branch was cut off. There seems to be water inside. A neighbor said it needs to be filled.

A: Holes that form from limb removal are common. They can be prevented by using proper arborist pruning techniques. But now that you have the hole, do not fill it. Research has shown that tar, expanding foam, concrete, and caulk inevitably crack around the edges and allow water into the hole. Protected from drying, the hole grows bigger. Do not try drilling into the trunk to drain the cavity. The drilling will damage the protective cell layers the tree has established to contain the rot. The best course of action usually is to leave tree hollows alone. If you simply must do something, fashion a “roof” over the hole using sheet tin or aluminum, painted to match the tree.  This might shed water enough water to keep the hole dry.