When pruning, branches shall be cut back to a live lateral at least what fraction of the severed branch diameter?

• A. 1/3 the diameter
• B. 1/2 the diameter
• C. 1/4 the diameter
• D. 2/3 the diameter

Answer: (A)

When pruning, you want the cut to land on a live lateral that is enough to supply tissue for proper wound closure. The rule says the remaining live lateral should be at least one-third of the diameter of the branch you’re removing. This provides enough cambial tissue to form a healthy callus and seal the wound, helping the tree resist decay and heal more reliably. If the lateral is smaller than that, the wound is too large relative to what’s left, healing is slower, and decay is more likely. You can cut back to a larger live lateral as well, since the requirement is “at least,” but one-third is the minimum threshold.