What is a major risk factor for limb failure in trees with narrow crotches?

Included bark is a significant risk factor for limb failure in trees with narrow crotches because it negatively affects the integrity of the tree's structure. When branches grow closely together, the bark that develops between them can get trapped as they grow, leading to a situation where the bark is included rather than shed. This inclusion creates a weak point in the connection between the branches, reducing their overall strength and making them more susceptible to failure under stress from wind, weight, or other environmental factors.

This phenomenon is particularly problematic in narrow-angled branch unions, where the lack of sufficient wood tissue to support the branches compounds the issue. Trees exhibiting included bark may show signs of limb failure during high-stress situations because the union lacks the necessary structural support, making it one of the primary concerns for arborists and landscape professionals managing tree health and stability.