INSECTICIDES DO NOT AFFECT COTTON (GOSSYPIUM-HIRSUTUM) RESPONSE TO IMAZAQUIN AND IMAZETHAPYR

Field and greenhouse experiments evaluated interactions of soil-applie d insecticides and imazaquin and imazethapyr on growth and development of cotton. Imazaquin and imazethapyr were applied PPI at 0 to 6 and 0 to 16 g ae ha-1, respectively, in the greenhouse (plus a no-insectici de control), and 0 to 72 g ha-1 in the field in combination with aldic arb, disulfoton, and phorate (without a no-insecticide control) applie d in the seed furrow. Cotton shoot fresh weight in the greenhouse expe riment decreased linearly as herbicide rates increased. Greater reduct ions in shoot fresh weight were noted with imazaquin than with imazeth apyr. Compared with no insecticide, the methylcarbamate insecticide al dicarb and the organophosphate insecticides disulfoton and phorate did not affect cotton response to either herbicide. In the field, cotton injury increased while stand, yield, and maturity decreased as herbici de rates increased. Delayed maturity was due to a lower percentage of bolls produced on sympodia from main stem nodes four to nine. Imazaqui n caused greater injury, greater reductions in stand, greater delays i n maturity, and lower yields than did imazethapyr. Earlier maturity wa s noted with aldicarb-treated cotton. Compared with aldicarb, disulfot on and phorate did not alter cotton response to imazaquin or imazethap yr.