Carrier Volume Adjustments Improve Imazamethabenz Efficacy

Abstract

Reduced-rate herbicide strategies, which rely on treatment of small weed seedlings, are not effective under all situations. The consistency of reduced-rate treatments may be improved by adjustments in application variables. Field experiments were conducted at Kalispell, MT, during 1994 and 1995 to determine the effects of carrier volume on the efficacy of reduced-rate imazamethabenz applications for wild oat control in barley. Imazamethabenz was applied to two- and four-leaf wild oat plants at 0.26 and 0.52 kg ai/ha in carrier volumes of 75, 150, and 225 L/ha. Wild oat control generally increased as carrier volume increased, regardless of imazamethabenz rate or wild oat growth stage. However, increasing carrier volumes had a greater positive effect on wild oat control when imazamethabenz was applied to two-leaf vs. four-leaf wild oat seedlings. Barley yield was most affected by the duration of wild oat interference, with the greatest yield being observed with the earliest application. Barley yield tended to increase as carrier volume increased in 1 of 2 yr. These results indicate that wild oat control with imazamethabenz can be enhanced by increasing carrier volume, providing more consistent wild oat control from reduced imazamethabenz rates.