Influence of Simulated Imazapic and Imazethapyr Herbicide Carryover on Cotton (Gossypium hirsutumL.)

Abstract

Field studies were conducted during the 2001 and 2002 growing seasons in the Texas peanut growing regions to simulate residual concentrations of imazapic and imazethapyr in the soil and subsequent effects on cotton (Gossypium hirsutumL.). Simulated imazapic or imazethapyr rates included 0, 1/64X (1.09 g ai/ha), 1/32X (2.19 g ai/ha), 1/16X (4.38 g ai/ha), 1/8X (8.75 g ai/ha), 1/4X (17.5 g ai/ha), and 1/2X (35 g ai/ha) of the full labeled rate for peanut (Arachis hypogaeaL.) and incorporated prior to cotton planting. Cotton stunting with imazapic or imazethapyr was more severe at Denver City than other locations. All rates of imazapic and imazethapyr resulted in cotton stunting at Denver City while at Munday and Yoakum the 1/8X, 1/4X, and 1/2X rates of imazapic resulted in reduced cotton growth when compared with the untreated check. At all locations imazapic caused more stunted cotton than imazethapyr. Cotton lint yield was reduced by imazapic or imazethapyr at 1/4 X and 1/2 X rates at all locations when compared with the untreated check.