Internal defects associated with pruned and nonpruned branch stubs in black walnut

Abstract

Dissections of 50 branch stubs from seven black walnut trees revealed that some discolored wood was associated with all stubs, and that ring shakes and dark bands of discolored wood were associated with 14 of 17 stubs that were "flush cut" (branch collar removed) 13 years earlier while they were living or dead. Ring shakes formed along the barrier zone tissues that separate the wood formed before wounding from wood that formed subsequently. Pruning done early in the life of the tree eliminates these problems. When pruning is done late in the life of a tree, care must be taken not to remove the branch collars that form around the bases of dying and dead branches. A pictorial description of the internal defects associated with the pruned and nonpruned stubs is presented.

Citation

Shigo, Alex L.; McGinnes, E. Allen, Jr.; Funk, David T.; Rogers, Nelson. 1979. Internal defects associated with pruned and nonpruned branch stubs in black walnut. Res. Pap. NE-440. Broomall, PA: U.S. Department of Agriculture, Forest Service, Northeastern Forest Experiment Station. 27p.