Inspecting Trees for Dangerous Defects

Defective trees can cause personal injury and property damage. Hazard tree management has increased in recent years due to safety and liability concerns resulting from preventable accidents. A “hazard tree” is a tree with structural defects likely to cause failure of all or part of the tree, which could strike a “target.” A target can be a vehicle, building, or a place where people gather such as a park bench, picnic table, street, or backyard.

Inspecting Trees

Consider the items on this checklist when inspecting your trees:

• Tree Condition: Poor conditions include many dead twigs, dead branches or small, off-color leaves. Good conditions include full crowns, vigorous branches, and healthy, full-sized leaves. But you need to look further...for the health of branches and trunks.
• Tree Species can affect hazards because come tree species are prone to specific types of defects. For example aspen are prone to youthful breaks due to decay; some species of maple and ash can form weak branch unions.
• Tree Age and Size are affected by constant stress. Older trees that have accumulated multiple defecs and extensive decay can be especially prone to damage.

Inspect your trees every year. A thorough inspection is easiest after leaf drop in the fall, and after leaf-out in spring. It's important to routinely inspect trees after every severe storm.

Look for dead wood, cracks, weak branch unions, decay, cankers, root problems, and poor tree architecture.

Corrective action provides some choices, depending on the problems. You can move the tree to a better location; prune the tree or remove the tree.

For more thorough guidelines on "Recognizing Hazardous Defects in Trees," check out this helpful and estensive on-line guidebook by the USDA Forest Service.

SOURCE: Forest Service: Recognize Hazardous Defects in Trees

PROBLEM: Danger and liability

SOLUTION: Regular inspection and care of your trees with pruning, cabling, bracing or tranpanting, or removal of the tree.