Wind, snow and ice are rough on trees, and a tree with defects is more likely to fail. [UMass][Illinois Extension] Before winter storms reach Iowa City, Illinois Extension suggests learning to spot the weak points, especially on trees near a house, driveway or play equipment. [Illinois Extension]
What to look for
Dead branches: remove dead branches or dead trees right away, in any season. Dry, brittle dead wood doesn't bend and snaps more easily. [Illinois Extension]
Cracks: act right away if there are two or more cracks in the same area or a split goes through the bark into the wood. [Illinois Extension] Cracks on two sides of the trunk, or a crack next to decay or a cavity, are very dangerous. [UMass]
Tight, V-shaped forks: codominant stems with included bark have little sound wood holding them together and are more likely to fail under wind, ice or snow loads. Maple, ash, elm and Callery pear commonly form them. [UMass][Illinois Extension]
Cankers and decay: immediate action is recommended if a canker covers more than half the trunk's circumference. Soft, crumbly wood, cavities and fungal growth point to a higher risk of failure. [Illinois Extension]
Roots and lean: watch for damaged or decayed roots, girdling roots, and soil heaving or root plates lifting. A tree that has gradually straightened over time is usually fine, but a lean caused by wind, ice or snow can be a hazard. [Illinois Extension][UMass]
Call a pro for the big ones
A defect doesn't always mean a tree has to come down; arborists are trained to evaluate decaying trees and assess risk. [Illinois Extension] UMass also warns that badly cracked trees may not support a climber's weight. [UMass] After a storm, check your trees again for new damage. [Illinois Extension]
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