Bispyribac-sodium, sulfosulfuron, and interseeding creeping bentgrass for long-term control of roughstalk Bluegrass

Abstract

Roughstalk bluegrass (Poa trivialis L.) contamination is problematic on golf course fairways from the Midwest to the mid-Atlantic regions of the United States. Bispyribac-sodium and sulfosulfuron have potential to selectively control roughstalk bluegrass. Our objectives were to determine the most effective herbicide treatments for short- and long-term roughstalk bluegrass control and to determine if interseeding with creeping bentgrass (Agrostis stolonifera L.) after herbicide treatments will improve long-term control of roughstalk bluegrass or conversion to creeping bentgrass. Plots were treated with bispyribac-sodium or sulfosulfuron and then half of each plot was in-terseeded with creeping bentgrass in early August, 2 weeks after the final herbicide application in 2006, 2007, and 2008 in Indiana. Roughstalk bluegrass cover reduction was highest when treated with bispyribac-sodium at 56 or 74 g ha-1 a.i. applied four times or sulfosulfuron at 27 g ha-1 a.i. applied three times. Interseeding with creeping bentgrass improved long-term roughstalk bluegrass control and quickened conversion to creeping bentgrass. Furthermore, bispyribac-sodium and sulfosulfuron appeared to be more effective in the first2 yearsof the study whenseasonalheat stress was greater,which appeared to improve long-term roughstalk bluegrass control and promoted creeping bentgrass establishment. Chemical names used: {2,6-bis[(4,6-dimethoxypyrimidin-2-yl)oxy] ben-zoic acid} (bispyribac-sodium), {1-[4,6-dimethoxypyrimidin-2-yl]-3-[2-ethanesulfonyl-imidazo(1,2-a)pyridine-3-yl) sulfonyl]urea} (sulfosulfuron).