Your Backyard Forest - Identify and Manage Hazardous Tree Defects

• #3- Weak Branch Unions: Weak branch unions are places where branches are not strongly attached to the tree. A weak union occurs when two or more branches grow so closely together that bark grows between the branches and inside the union. This ingrown bark does not have the structural strength of wood and the union can become very weak. The inside bark may also act as a wedge and force the branch union to split apart. Trees with a tendency to form upright branches, such as elm and maple, often produce weak branch unions.
Act immediately if . . .
• A weak branch union occurs on the main stem. • A weak branch union is associated with a crack, cavity, or other defect.

• #4- Decay: Decaying trees are prone to failure, but the presence of decay alone does not necessarily mean failure. Still, advanced decay (soft, crumbly wood with a cavity) is serious. Evidence of fungal activity including mushrooms and conks are indicators of advanced decay.
A tree usually decays from the inside out, forming a cavity, but sound wood is added to the outside of the tree as it grows. Trees with sound outer wood shells are relatively safe. Still, evaluating the safety of a decaying tree is usually best left to trained arborists.
Act immediately if . . .
• Advanced decay is associated with cracks, weak branch unions, or other defects. • A large branch is decayed. • The thickness of sound wood is less than 1 inch for every 6 inches of diameter, at any point on the stem.