Johnsongrass Control with DPX-V9360 and CGA-136872 in Corn (Zea mays) in Virginia

Abstract

Five field experiments were conducted at two locations in Virginia during 1988–89 to evaluate DPX-V9360 and CGA-136872 for postemergence control of johnsongrass in field corn grown under no-till and conventional conditions. DPX-V9360 at rates of 35 (except in no-till plots), 52, and 69 g ai ha-1applied to 8-leaf johnsongrass was 88 to 98% effective in 1988. CGA-136872 at 25, 49, and 99 g ha-1was 80% effective at the highest rate. Applications of these herbicides to 6-leaf johnsongrass resulted in 69% or less control. DPX-V9360 at 35, 52, and 69 g ha-1and CGA-136872 at 20 and 40 g ha-1applied to johnsongrass up to 48 cm in height provided 77 to 97% control at 7 WAT3in an excellent stand of conventionally planted corn during 1989. Crop yields were more than doubled with herbicide treatments relative to yields in control plots. At a second location where crop damage caused by other factors resulted in a weak stand, DPX-V9360 provided 61 to 96% control compared to 29 to 56% control with CGA-136872.