Holey Trees

In the story of about the Oak Fungi anonymous asked if she should have her landlord seal with tar the hole in her oak tree.

I found this answer on a Polk County Horticultural site:

Most Frequently Asked Questions About Trees

"1. My tree has a big hole in the trunk what should I do? There is a popular misconception that holes in tree trunks and/or large limbs should be filled with concrete or some other material to plug the hole. At the present time, University of Florida researchers feel that the hole should just be left alone. Putting concrete or plumbers foam in the hole may make the rotting potential worse, than just left alone. Trying to clean the out the hole by digging out rotten wood may do more damage than good. Keep in mind that this hole is an indication that the tree has been previously damaged in some way which could eventually lead to the death of the tree. "