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.
Nomenclature: 2,4-D amine, 2,4-D ester, dicamba, fluroxypyr, glyphosate, imazapic, picloram, trifloxysulfuron, bermudagrass, Cynodon dactylon (L.) Pers. ‘Coastal’, junglerice, Echinochloa colona (L.) Link #3 ECHCO, large crabgrass, Digitaria sanguinalis (L.) Scop. # DIGSA.
Additional index words: Bermudagrass sprigs, establishment, injury, phytotoxicity.
Abbreviations: ai, active ingredient; ae, acid equivalent; DAT, days after treatment; NIS, nonionic surfactant.
