Response of Coastal Bermudagrass (Cynodon dactylon) to Various Herbicides and Weed Control during Establishment

Abstract

Field experiments were conducted to determine the effects of application timings and various herbicides on newly established ‘Coastal’ bermudagrass in 2001, 2002, and 2003. The experimental design was a split plot with three replications. Main plots consisted of three herbicide application timings of 1, 14, and 28 d after planting (DAP), and the subplots were 16 herbicide treatments. The hormone herbicides (picloram at 0.19 kg ae/ha + fluroxypyr at 0.19 kg ae/ha, picloram at 0.08 kg/ha + 2,4-D amine at 0.28 kg ae/ha, picloram at 0.15 kg/ha + 2,4-D amine at 0.56 kg/ha, 2,4-D amine at 2.2 kg/ha, 2,4-D amine at 1.2 kg/ha + dicamba at 0.42 kg ae/ha, and 2,4-D ester at 2.3 kg ae/ha) applied 1 DAP controlled large crabgrass 55 to 85%, did not injure Coastal bermudagrass sprigs, and aided establishment resulting in 22 to 27% ground cover in 2001 and 25 to 42% ground cover in 2002. Imazapic at 0.02, 0.035, and 0.05 kg ai/ha applied 1 and 14 DAP injured Coastal bermudagrass 5 to 45% across years, yet these plots had 20 to 54% ground cover compared with only 3 to 7% ground cover in the nontreated area in 2001, 2002, and 2003. The reduced rate of glyphosate (0.21 kg ae/ha) injured Coastal bermudagrass less than 8% and controlled large crabgrass 86 to 90% when applied 14 DAP, resulting in 43, 25, and 18% ground cover in 2001, 2002, and 2003, respectively. Trifloxysulfuron at 0.02 kg ai/ha applied 1 and 14 DAP did not injure Coastal bermudagrass sprigs, controlled junglerice 90%, and resulted in 73 and 52% ground cover, respectively. Coastal bermudagrass establishment was greatly increased when weeds were controlled.