To minimize trunk decay, what should be left on the trunk when removing a live branch?

Leaving the branch bark ridge intact while removing a live branch is crucial for minimizing trunk decay. The branch bark ridge serves as a natural boundary between the live tissue of the branch and the trunk. This ridge contains cells that can aid in wound closure and protection against decay organisms. When removing a branch, cutting just outside the branch bark ridge allows the tree to more effectively seal the wound, thus reducing the risk of infection and decay.

In contrast, cutting too close to the trunk or removing parts of this ridge can expose more cambial tissue, increasing vulnerability to pathogens and pests. This is why it is important to consider the anatomical structure of the tree during pruning operations, as it can significantly impact tree health and longevity.