Effects of Bentazon, Imazaquin, or Chlorimuron on Haloxyfop or Fluazifop-P Efficacy

Abstract

Field studies were conducted to measure the response of sorghum [Sorghum bicolor(L.) Moench. ‘Conlee's Top Hand’] to foliar applications of haloxyfop {2-[4-[[3-chloro-5-(trifluoromethyl)-2-pyridinyl] oxy] phenoxy] propanoic acid} or fluazifop-P {(R)-2-[4-[[5-(trifluoromethyl)-2-pyridinyl] oxy] phenoxy] propanoic acid} plus either bentazon [3-(1-methylethyl)-(1H)-2,1,3-benzothiadiazin-4(3H)-one 2,2-dioxide] at 0.84 kg ai/ha imazaquin {2-[4,5-dihydro-4-methyl-4-(1-methylethyl)-5-oxo-1H-imidazol-2-yl]-3-quinolinecarboxylic acid} at 0.21 kg ae/ha, or chlorimuron {2-[[[[(4-chloro-6-methoxy-2-pyrimidinyl) amino] carbonyl] amino] sulfonyl] benzoic acid} at 12 g ae/ha. Tank-mixing imazaquin or chlorimuron with haloxyfop or fluazifop-P reduced phytotoxicity to sorghum 12 days after treatment (DAT) by 14 to 64% compared to applications of haloxyfop or fluazifop-P alone. Much of this antagonism was reduced 24 DAT as imazaquin and chlorimuron apparently delayed the activity of haloxyfop and fluazifop-P when losses in activity ranged from 13 to 21%. Increases in haloxyfop and fluazifop-P rates tended to reduce the severity of the antagonism. Tank-mixing bentazon with haloxyfop or fluazifop-P did not reduce phytotoxicity to sorghum compared to applications of haloxyfop and fluazifop-P alone.