Selective herbicides useful against grassy weeds - contain substd. phenoxy-alkanoic acid or -alkanol derivs. and a methylenedioxy-benzene synergist

摘要

New agents for combating grassy weeds contain a cpd. of formula (I) and a methylenedioxybenzene deriv. of formula (II): In (I), either (a) X = 0 and n = 0; Y = 4-trifluoromethylphenyl, 2-chloro-4-trifluoromethylphenyl, 4-chlorophenyl, 4-bromo-2-chlorophenyl, 5-chloro-2-pyridyl, 3,5-dichloro-2-pyridyl, 6-chloro-2-benzothiazolyl, 5-chloro-1-benzothiazolyl, 5-chloro-2-benzoxazolyl or 6-chloro-2-benzoxazolyl; and W = COOR1 (R1 = 1-8C alkyl, H or cation of organic or inorganic base; or (b) X = 0 and n = 1; Y = as under (a) or 2,4-dichlorphenyl; and W = OH; or (c) X = O and n = 2; Y = 4-trifluoromethylphenyl or 2-chloro-4-trifluoromethylphenyl; and W = COOR1; or (d) X = CH2 and n = 0; Y = 2,4-DICHLOROPHENYL; AND W = COOR1. In (II) Y = H, halogen, alkyl or a linear, branched or cyclic polyether gp. X = linear, branched or cyclic polyether group, halogen, CN, CH2C N, CH2OH, CH2SH, ethynyl, -CH=NOR, -C H=CH-R1, -CONR2R3, -CSNR2R3, -CH2CH(CH3)-SO-(CH2)7CH3, cycloalkyl substd. by 1 or 2 alkoxycarbonyl and/or alkyl gps. a cycloalkanone gp. opt. substd. by alkyl and/or alkoxycarbonyl, or a cycloalkenone gp. opt. substd. by alkyl; or X+Y = alkylene opt. substd. by 1 or 2 alkoxycarbonyl and/or alkyl gps.; R = alkylcarbonyl; R1 = pyridyl; and R2, R3 = H, alkyl, alkoxycarbonylalkyl, aryl or haloaryl. (I) and (II) act synergistically against annual and perennial grassy weeds such as Alopecurus myosuroides, wild oats, Echinochloa, Setaria, Digitaria, Agropyron repens, Sorghum halepense, Cynodon dactylon and Panicum spp. Selectivity is high, so that the combinations can be used in crops such as cereals, soya beans, cotton, sugar beet etc.