EFFECT OF OIL ADJUVANTS AND NITROGEN-FERTILIZER ON THE EFFICACY OF IMAZETHAPYR APPLIED AT CONVENTIONAL AND ULTRALOW SPRAY VOLUMES

Field experiments evaluated pitted morningglory, velvetleaf, and barny ardgrass control in soybean with imazethapyr applied alone and with ei ther crop oil concentrate at 1.0% v/v, a blend of methylated seed oil and organosilicone surfactant, or a blend of methylated seed oil, phos phate esters, and organosilicone surfactant at 0.5% v/v, each with and without a 28% N mixture of urea and ammonium nitrate (URAN) applied a t 2.3 L/ha. Treatments were applied at spray volumes of 94 and 9.4 L/h a. Control of each species was often increased with the addition of bo th oil adjuvants and URAN, The blend of methylated seed oil, phosphate esters, and organosilicone surfactant and the blend of methylated see d oil and organosilicone surfactant were each more effective than crop oil concentrate on pitted morningglory and barnyardgrass, while each oil adjuvant was similar on velvetleaf, The URAN effectively increased imazethapyr control of all species. Control of all species was simila r at the spray volume of 9.4 L/ha and at 94 L/ha.