Response of Creeping Bentgrass to Spring-applied Herbicides

Creeping bentgrass (Agrostis palustris Huds.) putting greens are commonly infested with crabgrass (Digitaria spp.) and goosegrass [Eleusine india (L.) Gaertn.]; however, many herbicides have the potential to severely injure this turfgrass species. A field investigation was conducted over 2 years to determine the tolerance of creeping bentgrass to various herbicides. Trifluralin plus benefin (2.2 to 6.7 kg·ha -1 ), dithiopyr (0.37 to 1.1 kg·ha -1 ), and prodiamine (0.5 to 1.7 kg·ha -1 ) did not injure creeping bentgrass. Pendimethalin caused only slight injury when applied at 3.4 kg·ha -1 , but injury increased in 1 of 2 years when applied at ≥6.7 kg·ha -1 . Creeping bentgrass was severely injured when treated with benefin plus oryzalin (≥4.5 kg·ha -1 ), fenoxaprop (0.07 kg·ha -1 ), and oxadiazon (3.4 kg·ha -1 ) granular and WP formulations and, therefore, should not be applied to the turf. Chemical names used: N -butyl- N -ethyl-2, 6-dinitro-4-(trifluoromethyl) benzenamine (benefin); S,S -dimethyl 2-(difluoromethyl-4-(2-methylpropyl)-6-(trifluoromethyl-3, 5-pyridinedicarbothioate (dithiopyr); (±) 2-[4-[(6-chloro-2-benzoxazolyl)oxy]phenoxy]propanoic acid (fenoxaprop); 4-(dipropylamino)-3,5-dinitrobenzenesulfonamide (oryzalin); 3-[2,4-dichloro-5-(l-methylethoxy)phenyl]-5-(1,1-dimethylethyl)-1,3,4-oxadiazol-2-(3H)-one (oxadiazon); N -(1-ethylpropyl)-3,4-dimethyl-2,6-dinitrobenzenamine (pendimethalin); 2,4-dinitro N,N -dipropyl-6-(trifluoromethyl)-1,3-benzenediamine (prodiamine); 2,6-dinitro- N-N -dipropyl-4-(trifluoromethyl)benzenamine (trifluralin).