Rotten wood in basswood tree.

Asked May 16, 2017, 5:28 PM EDT

40 year old 15 in DBH Basswood. Has sunscald on SW side 5 ft above ground. Area is about 15 in tall and about 6 in wide in middle tapering to ends. There is damp rotten wood which can be pulled out. Tree appears to be very healthy. What should be done with it?

Washington County Minnesota

3 Responses

Thank you for the question. Visible rot to the tree trunk indicates there could be internal decay and if it's severe enough, the tree should be removed. We suggest you hire a certified arborist to come out and examine the tree. Sometimes if these wounds aren't too severe, the tree can recover but you need a professional to tell you what to do. Here's how to hire a certified arborist:
Often, a tree with major health problems looks good in the spring because it is living on stored energy from last year. The tree can quickly use this up and if the trunk is severely compromised, the death of the tree is not far behind.

Thank you for contacting Extension.

I prefer to not remove the tree or have an expert examine it. Generally, is it good to:

1. Remove the rotten wood?
2. After removing, spray the cavity with a fungicide?
3. Fill the cavity?
4 Do nothing

Without a diagnosis and evaluation of the tree, we can't suggest a simple plan of action except to say that The University doesn't recommend using any chemical product unless you know what the problem is you are trying to treat, and we don't advise filling a cavity or removing debris because this can cause more trouble for the tree. This article describes tree cavities and some do's and don'ts:
The University of Minnesota has a self diagnostic tool that might help you diagnose the problem and decide upon a course of action:
Basswood aren't terribly long lived trees and their wood is soft. It's not unusual for the older trees to be rotten and hollow inside. If the tree is rotten and a danger to property or people, it should be removed.