Although arborists have tools available to measure how much sound and decayed wood is present in a tree, it is often less clear how much decay a tree can tolerate while still remaining a stable structure. Decay in trees is common, but not all decay is a reason for action. There are many variables that influence the stability of trees with decay. Some of these variables include tree and pathogen species; tree age and health; canopy architecture, height, and weight distribution; exposure to wind, snow, and ice; wood strength and toughness; root structure; and soil conditions.
The best thing for a homeowner or property owner to do is set up a tree hazard/tree risk assessment with an ISA certified arborist to give them a better idea of the tree’s structure. However, any tree can fail given the right conditions.