Effects of herbicide release on the growth of 8- to 12-year-old hardwood trees

In 8- to 12-year-old Appalachian hardwood stands, crop trees were released by stem injecting competing trees with a 20 percent aqueous solution of glyphosate. Species released were black cherry, red oak, and sugar maple. Release treatments were (a) injection of all trees within a 5-foot radius of the crop tree bole and (b) injections of all trees whose crown touched the crop tree. Five-year diameter growth of all species was significantly increased by both release treatments, but height growth was not affected by either treatment. Survival of released crop trees was higher and crownclass retrogression of released trees was less than unreleased trees. Glyphosate was effective in controlling most hardwood species during the 5 years of observation.