Incorporating CGA-248757 and Flumiclorac into Annual Weed Control Programs for Corn (Zea mays) and Soybean (Glycine max)1

Abstract

Field trials evaluated weed control in corn and soybean with CGA-248757 and flumiclorac. CGA-248757 and flumiclorac were applied to 5-, 45-, and 60-cm-tall velvetleaf. Visual control ratings 7 d after treatment (DAT) indicated the greatest control of velvetleaf in corn with CGA-248757 applied to velvetleaf when 5 or 45 cm tall, whereas the greatest control with flumiclorac occurred when applied to 5-cm-tall velvetleaf. However, ratings 21 DAT to 60-cm-tall velvetleaf indicated velvetleaf control with both herbicides was greatest when applied to plants 45 or 60 cm tall. CGA-248757 or flumiclorac applied postemergence (POST) following metolachlor or metolachlor plus atrazine preemergence (PRE) improved velvetleaf control compared with metolachlor plus atrazine alone. Similarly, tank mixtures of CGA-248757 or flumiclorac with 2,4-D following metolachlor PRE provided greater velvetleaf control compared with metolachlor PRE followed by 2,4-D POST. Velvetleaf control in corn was greater when CGA-248757 or flumiclorac were tank mixed with nicosulfuron plus atrazine or nicosulfuron plus dicamba. In soybean, metolachlor plus metribuzin plus clomazone PRE, metolachlor PRE followed by flumiclorac POST, and metolachlor plus metribuzin PRE followed by CGA-248757 or flumiclorac POST provided greater than 85% control of giant foxtail, common lambsquarters, redroot pigweed, and velvetleaf 56 d after POST treatments (DAPO) in 1997. Additionally, glyphosate applied late postemergence (LPOST) and tank mixtures of glyphosate with CGA-248757 or flumiclorac LPOST provided greater than 90% control of these same weed species in 1997. However, only metolachlor plus metribuzin PRE followed by CGA-248757 or flumiclorac POST and imazethapyr plus CGA-248757 or flumiclorac POST provided greater than 80% giant foxtail, common lambsquarters, redroot pigweed, and velvetleaf control 56 DAPO in 1998.Nomenclature: Atrazine; 2,4-D; CGA-248757 (proposed common name, fluthiacet), methyl[[2-chloro-4-fluoro-5-[(tetrahydro-3-oxo-1H,3H-[1,3,4]thiadiazolo[3,4-a]pyridazin-1-ylidene)amino]phenyl]thio]acetate; clomazone; dicamba; flumiclorac; glyphosate; imazethapyr; metolachlor; metribuzin; nicosulfuron; common lambsquarters, Chenopodium album L. #3 CHEAL; corn, Zea mays L. # ZEAMA; giant foxtail, Setaria faberi Herrm. # SETFA; redroot pigweed, Amaranthus retroflexus L. # AMARE; soybean, Glycine max (L.) Merr. # GLYMA; velvetleaf, Abutilon theophrasti Medik. # ABUTH.Additional index words: Antagonism, herbicide interaction, Protox, bromoxynil, clethodim, oxasulfuron, quizalofop, sethoxydim, ABUTH, AMARE, CHEAL, DIGSA, GLYMA, SETFA, XANST, ZEAMA.Abbreviations: COC, crop oil concentrate; DAP, days after planting; DAPO, days after postemergence treatment; DAT, days after treatment; LPOST, late postemergence; NIS, nonionic surfactant; POST, postemergence; Protox, protoporphyrinogen oxidase; PRE, preemergence; UAN, 28% urea ammonium nitrate.