Decay Patterns in Silver Maple (Acer saccharinum) Trees Converted from Roundovers to V-Trims

Abstract

Trees growing beneath electrical power lines are often subjected to heading cuts made during roundover trimming. Heading cuts create wounds that allow decay to enter the branch, and a decay column will form if the tree does not contain it with compartmental reaction zones. The presence of a sizable decay column may predispose the leader to failure, especially when the tree has been converted from a roundover to a V-trim. The objectives of this study were to quantify the amount of decay in silver maples (Acer saccharinum L.) converted from roundover to V-trims and to develop models to allow utility arborists to estimate the extent of internal decay columns. Parent stems (leaders) were removed from converted trees, cut into 50 cm (20 in) sections, and measured for internal and external decay. Eighty percent of the leaders had internal decay columns beginning within 50 cm (20 in) of the heading cut and internal decay columns were found to be over 2 times longer than the length of external decay. Models are presented to predict the length and volume of internal decay from external measurements on the leader, including length of external decay.