Response of Bermudagrass (Cynodon dactylon) Turf to Winter-Applied Herbicides

Paraquat (1,1′-dimethyl-4,4′-bipyridinium ion), 2,4-D [2,4-dichlorophenoxy)acetic acid], dicamba (3,6-dichloro-o-anisic acid), and 2,4-D plus dicamba were applied as postemergence herbicide treatments in two experiments to weed-free dormant bermudagrass [Cynodon dactylon(L.) ♯3CYNDA] turf in the Piedmont region of Georgia. Herbicides were applied as a split application to separate plots on February 2 plus February 16 and February 16 plus March 3 (± 4 days) on four bermudagrass cultivars (‘Tifway’, ‘Tifgreen’, ‘Tifdwarf’, and ‘Ormond’) in one experiment and to Tifway with vertical mowing treatments for thatch removal in a second experiment. In 2 of 3 years, paraquat applied to dormant turf in February delayed growth of bermudagrass in April. The growth of Tifway and Tifdwarf was retarded more from paraquat at 1.2 kg ai/ha in one year than Tifgreen or Ormond. Dicamba applied alone or with 2,4-D delayed turf growth in early spring more than did 2,4-D alone. In thatch-free turf, selected treatments of paraquat, dicamba, and 2,4-D plus dicamba also delayed spring growth of bermudagrass more than did 2,4-D.