Wednesday, 9 November 2005
20

Chemical Control of Dallisgrass (Paspalum Dilatatum Poir.) in Bermudagrass.

Gerald M. Henry and Fred Yelverton. North Carolina State University, 4401 Williams Hall, Raleigh, NC 27695-7620

Currently, chemical control of dallisgrass is neither efficient, nor cost effective. Typical control programs include multiple applications of MSMA, which can be phytotoxic to warm-season turfgrass, or applications of glyphosate, which can be even more harmful to non-target plants. Furthermore, these control methods are not entirely effective in eliminating dallisgrass from turf. RevolverTM, which contains the sulfonylurea active ingredient foramsulfuron, was recently introduced for use on turfgrass. Revolver is labeled for the control of several weeds in warm-season turf including goosegrass, annual bluegrass, perennial ryegrass, tall fescue, henbit, and doveweed. Preliminary studies have suggested that Revolver may help control dallisgrass present in bermudagrass turf. Field experiments were conducted in 2003 and 2004 to quantify the efficacy of herbicides and herbicide programs in the control of dallisgrass in bermudagrass turf. Treatments were applied using a CO2 backpack sprayer equipped with XR8004VS nozzle tips and calibrated to deliver 304 L/ha at 290 kPa. Data were subjected to analysis of variance (ANOVA) and means were separated using Fisher's Protected LSD at the 0.05 significance level. Data were combined over locations in 2004. Two and three applications of MSMA provided 68% and 89% control 4 WAIT (weeks after initial treatment), respectively, but control declined to 51% and 72% 12 WAIT, respectively. Revolver applied twice and MSMA followed by Revolver 1 WAIT provided moderate control (65%) 4 WAIT, but control declined to 40% 12 WAIT. Delaying the application of Revolver 2 WAIT of MSMA provided better control than applying 1 WAIT, but control never exceeded 64% 12 WAIT. The addition of a second application of MSMA one week after applying Revolver (145 g ai/ha) provided the highest level of observed control (93%) 12 WAIT. No other treatments provided adequate control of dallisgrass 12 WAIT (<30%).

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