Effect of Trunk Injection of Three Growth Regulators on Sprout Growth in Silver Maple

Abstract

A short-term greenhouse study was conducted to evaluate growth retardation capabilities of potential plant growth regulators for silver maple. Two-year-old silver maple seedlings were pruned and trunk-injected with the growth regulators MBR 18337 {N-[4-(ethylthio)-2-(trifluoromethyl) phenyl]-methane-sulfonamide}x EL-500 {a-(1- methylethyl)-a-[4-(trifluromethoxy)phenyl]-5-pyrimidinemethanol]} and PP 333 {(2RS, 3RS)-1-(4-chlorophenyl)-4,4-dimethyl-2-(1,2,4-triazol-1-yl)pentan-3-ol}. All three growth regulators caused a significant reduction in the number of internodes per unit sprout length, when measurements were made three months after injection. EL-500 and PP 333 were the more effective. A high application rate of MBR 18337 (5 mg/seedling) caused the initial growth to exhibit phytotoxic symptoms, although this was temporary. Neither EL-500 or PP 333, at the application rates used, caused any malformed growth.