Trees provide significant benefits to our homes and communities, but they may also become liabilities when they fall or break apart, causing property damage, personal injuries, and power outages. Although some tree failures are unpredictable and cannot be prevented, many failures can be prevented from occurring. In fact, it is an owner’s responsibility to ensure that a tree on their premises poses no risk to people or property.
Prevention begins with properly selecting and choosing an appropriate location (right plant–right place). It’s followed by planting the tree properly and then training or pruning it over the years in the landscape. Follow a “pruning for strength” or structural pruning strategy that focuses on maintaining a central leader and a framework of limbs that offer the strongest possible wind resistance. Refer to HGIC 1003, Principles & Practices for Pruning Trees. No tree is wind-proof, and factors such as soil condition, wind intensity, tree health, tree architecture, and age all factor into wind resistance. However, neglected or improperly pruned trees that have been topped or “hat-racked” are more at-risk to storm damage.
Improperly pruned or topped trees where large branches have been removed results in a weak canopy that can fail during storm events. The large, open-faced cuts are susceptible to invasions by disease-causing fungi.
R. F. Polomski, ©2021 HGIC, Clemson Extension.
The risk of strong winds leading to tree failures increases with age, so property owners must examine their trees for branch, trunk, and root defects. Follow this “7 Point Check-up List” to inspect your trees for potentially hazardous defects.
First step: Stand far enough away from your tree so you can look up into its canopy.
- Dead, hanging, or broken branches. Branches larger than 2 inches may cause damage if they fall and should be removed immediately.
- Leaning tree. See if your tree leans to one side or appears off-kilter. If you see exposed roots or a mound of soil near its base, this tree may be an imminent hazard that requires immediate action.
Second step: Walk up to the tree and closely examine the branches and trunk for defects.
- Multiple trunks. Look for cracks or splits in codominant stems. Wishbone-like trunks of equal diameter may separate during wind and ice storms. Also, closely examine trees with several branches that arise from the same point on the trunk; these branches may be weakly attached and tend to separate away from the trunk.
Codominant branches of nearly equal diameter may fail as a result of being poorly attached to the trunk. The presence of included bark, a crack or crevice that separates the two trunks, is another indicator of weakly attached limbs.
R. F. Polomski, ©2021 HGIC, Clemson Extension.
- Weak branch unions. Inspect large branches greater than 3 inches in diameter at a point where they attach to the trunk. A crack or split at the union indicates a high probability of failure and warrants action. You should remove the branch rather than wait for a storm to take it down.
- Trunk and branch cracks. If you find a crack in the trunk or branches, measure its depth with a pencil or similar object. If the crack extends beyond the bark and into the wood, contact an arborist to inspect it.
- Decayed wood. Inspect the trunk and large branches for cavities, cankers, mushrooms, and conks. Look for mushrooms and conks along the trunk and on exposed roots. These signs and symptoms are evidence of decay. Contact a trained arborist to conduct a risk assessment to evaluate the tree’s condition and its potential as a hazardous tree.
Mushrooms or conks (pictured) on branches, trunks, or at the base of the tree indicate advanced decay and a high probability of tree failure.
R. F. Polomski, ©2021 HGIC, Clemson Extension.
Third step: Finally, look down and inspect the base of the tree.
- Root problems. Examine the base of the trunk for damage from rodents, string trimmers, etc. Look for a soil mound, soil cracking near the root collar, or broken roots sticking out of the ground. Remove any soil or mulch away from the root collar and see if there is a flat side to the trunk. If you find any encircling, constricting roots, consult an arborist to address this problem.
A stem girdling root (left) and drip irrigation tube (right) constrict the trunk and affect the health and stability of this tree.
R. F. Polomski, ©2021 HGIC, Clemson Extension.
Consider hiring a certified arborist credentialed by the International Society of Arboriculture who possesses a Tree Risk Assessment Qualification. You may also want to choose an arborist from a Tree Care Industry Association Accredited company or a member of the American Society of Consulting Arborists. The arborist you hire should be licensed, bonded, and insured.
This 7 Point Check-up List may take less than 30 minutes to complete. However, when conducted twice a year, this hour-long investment of time benefits trees and everyone who resides with them.
