OPTIMIZING FOLIAR ACTIVITY OF ISOXAFLUTOLE ON GIANT FOXTAIL (SETARIA-FABERI) WITH VARIOUS ADJUVANTS

Greenhouse, laboratory, and field studies were conducted to evaluate t he potential of nonionic surfactant (NIS), crop oil concentrate (COC), methylated seed oil (MSO), and 28% urea ammonium nitrate (UAN) to enh ance whole plant efficacy, absorption, and spray retention of foliar a pplications of isoxaflutole to giant foxtail. In greenhouse studies, i soxaflutole at 10 g ai ha(-1) reduced giant foxtail growth 5%, whereas the addition of a spray adjuvant reduced giant foxtail growth at leas t 75%. The addition of UAN improved giant foxtail growth reduction whe n used in combination with isoxaflutole plus NIS. Isoxaflutole spray r etention on the leaf surface was increased with an adjuvant and a furt her increase was observed with the addition of UAN. Isoxaflutole appli ed with NIS, COG, and MSO resulted in 42, 60, and 91% C-14 absorption, respectively, compared to 21% absorption from isoxaflutole applied al one 24 h after treatment (HAT). Increased C-14 absorption and entry in to the cuticle when an adjuvant was utilized with isoxaflutole resulte d in greater translocation of C-14 from isoxaflutole out of the treate d leaf. Significant basipetal movement from foliar applications of C-1 4-isoxaflutole suggests phloem mobility. In field studies, isoxaflutol e applied with MSO provided greater giant foxtail growth reduction com pared to isoxaflutole applied with NIS and in some cases COC. The addi tion of UAN to isoxaflutole did not increase whole plant efficacy in f ield studies. These studies indicate isoxaflutole has excellent potent ial to be used for control of existing giant foxtail present at the ti me of corn planting if an adequate adjuvant is utilized.