Effect of Removal Pruning Cut Angle on Branches That Lack Collars

Background: When branches lack a defined collar, arborists are left without a clear target to guide removal pruning. A common recommendation is to cut at a 45° angle from the branch bark ridge. Cutting perpendicular to the branch axis as an alternative would minimize effective wound size, potentially reducing wood dysfunction in the remaining stem. Methods: A total of 92 Acer rubrum L. ‘Florida Flame’ and 102 Quercus virginiana Mill. ‘Highrise’ branches without visible collars were pruned one of two ways: 1.) removal cut angle 45° from the branch bark ridge (45°) or 2.) removal cut angle perpendicular to the branch axis (perpendicular). Three years later, pruned areas were harvested and assessed for wound closure and internal discoloration and decay, controlling for initial branch diameter, branch-to-parent-stem aspect ratio, sprout growth, and branch height. Results: In live oak, branch size and cut method affected the amount and length of discoloration observed. In red maple, discoloration and decay were largely a function of branch size and aspect ratio (i.e., the relative size difference between the removed branch and parent stem). In both species, cambial dieback was more common with perpendicular removal cuts, often negating any initial benefit associated with the smaller wound. Conclusions: When removing branches without a branch collar, we recommend making 45° cuts. Identifying which branches to remove or retain early in a tree’s life is important to avoid large branch removal cuts later.