Torpedograss is a serious problem in southern turfgrass, especially along the U.S. gulf coast. Studies were conducted during 1998, 1999, and 2000 to evaluate quinclorac for torpedograss control in bermudagrass turf. Three applications of quinclorac at 0.6 kg/ha spaced 21 d apart provided better torpedograss control (88%) than two applications at 0.8 kg/ha (69%) or one application at 1.7 kg/ha (69%). Two applications of quinclorac (0.8 kg/ha) plus diclofop (0.8 kg/ha) provided better torpedograss control (82%) than either herbicide applied alone when evaluated after a single season of application. Increasing the mowing interval prior to quinclorac application to allow for more foliage to be present did not improve control. Nitrogen application prior to quinclorac treatment did not improve torpedograss control. Long-term control will most likely require quinclorac applications for more than one season.
Nomenclature: Diclofop; quinclorac; bermudagrass, Cynodon dactylon (L.) Pers. × C. transvaalensis Burtt-Davey ‘Tifway’; torpedograss, Panicum repens L. #3 PANRE.
Additional index words: Application frequency, cultural practices, mowing interval, nitrogen fertility, turfgrass.
Abbreviations: LSD, least significant difference; POST, postemergence; WAIT, weeks after initial treatment.