Inspect your trees for their danger potential

Nancy Szerlag

One of the great charms of older neighborhoods is the stately centennial trees that line the streets. But aging trees can become hazards if they are not cared for.

Bob Polomski, Ph.D., from the Clemson University School of Agriculture, Forest and Environmental Science and a certified arborist, created the following checklist to teach homeowners how to examine their trees for defects that could cause damage or injury to property and humans along with those dreaded power outages.

Polomski says to begin by standing away from the tree and look at the canopy. Dead, hanging or broken branches larger than 2 inches in diameter should be removed before they fall and cause harm.

A thinning canopy and undersized leaves are an indication of trouble and a red flag.

A leaning tree can also be a signal for trouble, especially if there are exposed roots or a mound of soil near its base. A storm bringing straight-line winds could topple such a tree, so have a professional assess the tree’s stability ASAP.

Next, walk up to the tree and closely examine the branches and trunk for defects. Look for cracks and splits in the trunk. Large trees with multiple branches arising from the same point in the trunk may have weak attachments and separate during a storm, bringing down all or part of the tree.

Also look for cracks where branches larger than 3 inches in diameter are attached to the trunk. A split here indicates a high probability of failure and warrants action.

Polomski also recommends looking for trunk or branch cracks and measure their depth with a screwdriver. Shallow cracks in bark are not a problem, but cracks that go deeper than the bark are a sign of trouble and need to be addressed.

Inspect the trunk and large branches for cavities, cankers, mushrooms and conks — large growths. Mushrooms and conks at the base of a tree are a sign of decay. A trained arborist can evaluate the tree’s condition and its potential as a hazard.

The final step is to look down at the base of the tree. Damage from rodents, string trimmers, roots encircling the tree and/or a flat-sided trunk are all red flags and should be seen by a professional. Removing strangling roots and exposing buried root flairs using an air spade can save the life of a tree.

To find out more about care of trees and locate a certified arborist in your area, go to

Nancy Szerlag is a master gardener and Metro Detroit freelance writer. Her column appears Fridays in Homestyle. Email her at Szerlag You can also read her previous columns at