Environmental Influence on Bentgrass Treated with Silvex

Abstract

Colonial bentgrass (Agrostis tenuis Sibth) and creeping bentgrass (Agrostis palustris Huds) exhibited the most tolerance to 1/2, 1, 1 1/2, and 3 lb/A of 2-(2,4,5-trichlorophenoxy)propionic acid (silvex) when grown under cool temperatures, a long photoperiod, and a low pH medium. Injury from treatments was slight to moderate when applied from early to mid-spring, severe when made from late spring to early summer, and very severe when made from late summer to early fall. Silvex appeared to cause the most injury at the 1 and 1 1/2 lb/A rates. Injury was much less from the lower rate of 1/2 lb/A. Root fructosan concentrations decreased with increasing rates under cool temperatures and increased with increasing rates under high temperatures. Bentgrass appeared to tolerate silvex treatments better under low available moisture conditions than under high moisture levels.