Broadleaf Weed Control in Corn (Zea mays) and Soybean (Glycine max) with CGA-248757 and Flumiclorac Alone and in Tank Mixtures1

Abstract

Broadleaf weed control with postemergence applications of CGA-248757 and flumiclorac applied alone and in tank mixtures was evaluated in greenhouse and field studies. In greenhouse studies velvetleaf, common lambsquarters, redroot pigweed, common ragweed, common cocklebur, eastern black nightshade, and wild mustard shoot weight were reduced by 50% from 0.1, 2.9, 0.9, 1.1, 0.8, 0.4, and 1.2 g/ha of CGA-248757 and 0.7, 3.0, 2.4, 3.3, 3.0, 3.4, and 74.1 g/ha of flumiclorac, respectively. Under greenhouse conditions, tank mixtures of CGA-248757 or flumiclorac with atrazine, bentazon, bromoxynil, dicamba, halosulfuron, imazethapyr, lactofen, primisulfuron plus prosulfuron, or 2,4-D increased velvetleaf, common lambsquarters, redroot pigweed, or common ragweed control 14 d after treatment (DAT) when compared with the control provided by atrazine, bentazon, bromoxynil, dicamba, halosulfuron, imazethapyr, lactofen, primisulfuron plus prosulfuron, or 2,4-D applied alone. In field studies, adding CGA-248757 or flumiclorac to atrazine, bentazon, bromoxynil, dicamba, halosulfuron, imazethapyr, lactofen, CGA-277476, primisulfuron plus prosulfuron, or 2,4-D increased crop injury 3 DAT, but there was no reduction in corn or soybean yields as a result. In corn, tank mixtures of CGA-248757 or flumiclorac plus atrazine, dicamba, or 2,4-D increased velvetleaf control compared with treatments without CGA-248757 or flumiclorac. Tank mixtures of CGA-248757 or flumiclorac with primisulfuron plus prosulfuron increased common lambsquarters control compared with primisulfuron plus prosulfuron alone. Similarly, in soybean CGA-248757 or flumiclorac tank mixtures with bentazon or CGA-277476 increased control of redroot pigweed, and tank mixtures with lactofen increased common lambsquarters control. However, season-long broadleaf control in soybean with bentazon, lactofen, and CGA-277476 tank mixtures with CGA-248757 or flumiclorac did not provide acceptable weed control. Compared with imazethapyr alone the addition of CGA-248757 and flumiclorac improved soybean yield and provided season-long eastern black nightshade, common lambsquarters, redroot pigweed, and common ragweed control.Nomenclature: Atrazine; bentazon; bromoxynil; 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; CGA-277476 (proposed common name oxasulfuron), 2-[[[[(4,6-dimethyl-2-pyrimidinyl)-amino]carbonyl]amino]sulfonyl] benzoic acid, 3-oxetanyl ester; dicamba; flumiclorac; halosulfuron; imazethapyr; lactofen; primisulfuron; prosulfuron; 2,4-D; common cocklebur, Xanthium strumarium L. #3 XANST; common lambsquarters, Chenopodium album L. # CHEAL; common ragweed, Ambrosia artemisiifolia L. # AMBEL; corn, Zea mays L. Pioneer 3751, Dekalb 404SR, and Dekalb 493 SR # ZEAMA; eastern black nightshade, Solanum ptycanthum Dun. # SOLPT; redroot pigweed, Amaranthus retroflexus L. # AMARE; soybean, Glycine max (L.) Merr. Conrad # GLYMA; velvetleaf, Abutilon theophrasti Medik. # ABUTH; wild mustard, Brassica kaber (D.C.) L.C. Wheeler # SINAR.Additional index words: Acifluorfen, antagonism, chlorimuron, Digitaria sanguinalis, glyphosate, herbicide interaction, nicosulfuron, protox, Setaria faberi, sethoxydim, Sorghum bicolor, thifensulfuron.Abbreviations: COC, crop oil concentrate; DAP, days after planting; DAT, days after treatment; GR50, 50% growth reduction; NIS, nonionic surfactant; POST, postemergence; protox, protoporphyrinogen oxidase; UAN, 28% urea ammonium nitrate.