Selective Removal of Creeping Bentgrass from Kentucky Bluegrass with Sulfosulfuron

Abstract

Creeping bentgrass (Agrostis stolonifera L.) is well adapted to golf course greens, tees, and fairways but may become a weed in Kentucky bluegrass (Poa pratensis L.) roughs and lawns. The objectives of this study were to determine effects of sulfosulfuron rate and application date on control of creeping bentgrass and safety on Kentucky bluegrass. Field experiments were initiated in 2003 and 2004 in Ames, IA, and West Lafayette, IN. Single applications of sulfosulfuron at 0.011 or 0.022 kg·ha−1 were applied over a 9-week period during the fall of each year. Phytotoxicity on Kentucky bluegrass was recorded weekly and control of creeping bentgrass was determined in the spring after fall treatments. No treatment provided greater than 31% control, and there were few differences in control between the two rates of sulfosulfuron. In West Lafayette, late fall applications were the most effective providing up to 31% control of creeping bentgrass. Sulfosulfuron provided less than 18% control in Ames in either year. Kentucky bluegrass was tolerant of all sulfosulfuron applications. Late fall applications of sulfosulfuron may be useful in partially removing creeping bentgrass from a heavily contaminated sward of Kentucky bluegrass. Chemical names used: 1-(4,6-dimethoxypyrimidin-2-yl)-3-(2-ethylsulfonylimidazo[1,2-a]pyridin-3-ylsulfonyl)urea (sulfosulfuron)