Oak Tree & Ants

Q: I have several very old oak trees on my property that are full of ants. After reading your article about that ants not causing damage to the tree and actually cleaning out decay, I am wondering what causes the decay and if there is anything I can do to stop that process.

We had an Arborist look at one of the trees last year and he said there wasn't anything he could recommend to save the one that is the worst, but did not comment on the others.

Thank you in advance for any advice you can provide.

Carolyn

A: Decay is a natural process that is usually the result of a physical injury to a tree. In other words, most decay organisms cannot "break and enter" like a burglar -- they need to be given the opportunity to enter the tree through a wound.

There are many many ways to wound a tree. Pruning cuts, technically, are wounds, but most trees have natural defenses against decay from entering through pruning cuts if the pruning cuts are made in the proper fashion.

Most non-pruning injuries to trees are a result of human activity. Since most of our human activity is near the base of the tree, this is the most common place that injuries occur and decay can seize the chance to enter.

The way to stop the natural process of decay, then, is not to wound the tree! Injuries to the trunk or root flares at the base are common points of entry, as are damages to the roots themselves.

Root injury commonly occurs as a result of construction activity, i.e., driveway installation, house-building, etc. Since these are necessary activities, injuries to roots will continue to occur but we can minimize the impact with careful forethought and stay as far away from the trees as possible

This is where you want to call in a competent arborist in advance, to render good advice on preventing or reducing the impacts of any construction activities which, by the way, would also include any lawn rehabilitation or installation.

It sounds like your oaks may have had decay for a long time, and sometimes there is nothing you can do but remove a tree for safety's sake.

I recommend having a qualified arborist inspect your trees and give advice. You may have some hazardous trees in your yard and not know it, so this is definitely something worth checking out.