Response of Quackgrass (Elytrigia repens) Biotypes to Primisulfuron

Quackgrass biotypes collected from 15 locations exhibited differential response to primisulfuron at 20 g ha−1in field experiments at Hudson, NY during 1990 and 1991. Quackgrass control ranged from 23 to 100% 77 days after application (DAA) in 1990 and from 38 to 100% 88 DAA in 1991. The biotype from Montpelier, OH was the most tolerant both years. Differential response of quackgrass biotypes from five locations was confirmed in greenhouse experiments. The primisulfuron rate required to reduce shoot regrowth by 50% in the greenhouse was estimated at 15, 15, 17, 17, and 37 g ha−1for biotypes from Amherst, MA; Mahnomen MN; Fargo, ND; State College, PA; and Montpelier, OH, respectively. Quackgrass shoot regrowth was reduced more when primisulfuron was applied with the linear alcohol ethoxylate additive 1412-70 compared with Scoil, Sylgard 309, Agridex, or X-77.