Published online by Cambridge University Press: 12 June 2017
The phytotoxicity of seven herbicides after soil application was determined in the field and greenhouse. Clopropoxydim {(E,E)-2-[1-[[(3-chloro-2-propenyl)oxy] imino] butyl]-5-[2-(ethylthio)propyl]-3-hydroxy-2-cyclohexen-1-one}, sethoxydim {2-[1-(ethoxyimino)butyl]-5-(2-ethylthio)propyl]-3-hydroxy-2-cyclohexen-1-one}, the methyl ester of haloxyfop {2-[4-[[3-chloro-5-(trifluoromethyl)-2-pyridinyl]oxy]phenoxy]propanoic acid} applied to soil at 0.21 kg/ha, and the methyl ester of diclofop {(±)-2-[4-(2,4-dichlorophenoxy)phenoxy] propanoic acid}applied to soil at 1.12 kg/ha were phytotoxic to oats (Avena sativa L. ‘Moore’) in the field and greenhouse. These rates are equivalent to postemergence use rates of these herbicides. DPX-Y6202 {2-[4-[(6-chloro-2-quinoxalinyl)oxy] phenoxy] propanoic acid} and the butyl ester of fluazifop {(±)-2-[4-[[5-(trifluoromethyl)-2-pyridinyl]oxy] phenoxy] propanoic acid} applied to soil at 0.84 kg/ha or greater were phytotoxic to oats. The ethyl ester of fenoxaprop {(±)-2-[4-[(6-chloro-2-benzoxazolyl)oxy] phenoxy] propanoic acid} soil applied exhibited very limited phytotoxicity to oats. Oat stands were reduced when oats were seeded into soil treated with clopropoxydim, sethoxydim, haloxyfop, diclofop, DPX-Y6202, fluazifop, and fenoxaprop, with the amount of stand reduction decreasing from clopropoxydim to fenoxaprop. Oat fresh weight reductions were greatest with all herbicides when the herbicides were in contact with all underground parts (shoots, seeds, and roots). Oat fresh weight reductions were greater when either the shoot or seed of the germinating oat plants were exposed to the herbicides compared to root exposure. Foxtail millet (Setaria italica L. ‘Siberian’) was more susceptible to injury than oats or wheat (Triticum aestivum L. ‘Len’) when seeded into soil treated with any one of the seven postemergence grass control herbicides.