SLENDER SPEEDWELL (VERONICA-FILIFORMIS) CONTROL IN COOL-SEASON TURF WITH QUINCLORAC

Experiments were conducted to compare rates and formulations of quincl orac for postemergent control of slender speedwell in cool-season turf . A 50% ae wettable powder formulation (50WP) was compared with two gr anular formulations, a 1% clay granule (IG) and a 0.4% com cob granule (0.4G). Each formulation was applied at 0.3, 0.6, 0.8, and 1.1 kg ha- 1. Additionally, 2,4-D at 1.1 kg ha-1 was applied alone and in combina tion with quinclorac 50WP at 0.8 kg ha-1. Slender speedwell control wi th the 50WP or 0.4G formulations was superior to that obtained with th e IG. At lower rates, slender speedwell control with the 50WP was grea ter than with the 0.4G; however, the rates required to obtain 95% cont rol were not significantly different. Tank mixing quinclorac 50WP at 0 .8 kg ha-1 with 2,4-D at 1.1 kg ha-1 did not improve slender speedwell control but increased roughstalk bluegrass injury. Kentucky bluegrass , perennial ryegrass, and tall fescue were not injured by quinclorac. Roughstalk bluegrass and chewings fescue were temporarily discolored. Turf injury was rate-related and more severe with the 50WP than the IG formulation.