Combinations of Sethoxydim with Postemergence Broadleaf Herbicides in Sethoxydim-Resistant Corn (Zea mays)1

Field studies were conducted in 1995 and 1996 to investigate postemergence tank mixtures of sethoxydim with various acetolactate synthase (ALS)- and non–ALS-inhibitor herbicides for weed control in sethoxydim-resistant (SR) corn. Giant foxtail control with sethoxydim was 96% and was equal to control with tank mixtures of sethoxydim plus bentazon, dicamba, dicamba plus atrazine, bromoxynil, and nicosulfuron plus bromoxynil. Giant foxtail control with sethoxydim plus atrazine, sethoxydim plus bentazon plus atrazine, and sethoxydim plus ALS-inhibiting herbicides plus 2,4-D was reduced to 60 to 89%. Common ragweed control was equal to or above 91% for tank mixtures that included bentazon plus atrazine, dicamba, dicamba plus atrazine, halosulfuron plus 2,4-D, and CGA 152005 plus primisulfuron plus 2,4-D, and the tank mixture of nicosulfuron plus bromoxynil. Common lambsquarters control was equal to or above 91% from all broadleaf herbicide treatments except bentazon and the tank mixture of halosulfuron plus 2,4-D. In these studies, only tank mixtures of sethoxydim plus dicamba or dicamba plus atrazine controlled giant foxtail, common ragweed, and common lambsquarters equal to or greater than 91% in SR corn.Nomenclature: Atrazine; bentazon; bromoxynil; CGA 152005 (proposed name prosulfuron), 1-(4-methyl-6-methyl-triazin-2-yl)-3-[2-(3,3,3-trifluoropropyl)-phenylsulfonyl] urea; dicamba; 2,4-D; halosulfuron; nicosulfuron; primisulfuron; sethoxydim; common lambsquarters, Chenopodium album L. #3 CHEAL; common ragweed, Ambrosia artemisiifolia L. # AMBEL; giant foxtail, Setaria faberi Herrm. # SETFA; corn, Zea mays L. ‘Dekalb 592SR’.Additional index words: Herbicide-resistant corn, herbicide tank mixtures, sethoxydim-resistant corn.Abbreviations: ACCase, acetylcoenzyme-A carboxylase; ALS, acetolactate synthase (EC 4.1.3.18); COC, crop oil concentrate; DAT, days after treatment; MCB, multiple comparisons with the best; NIS, nonionic surfactant; POST, postemergence; SR, sethoxydim resistant.