Response of Sugarbeets and Weeds to Phenmedipham and Two Analogues

Responses of weeds and sugarbeets ( Beta vulgaris L.) to postemergence treatments of methyl m -hydroxycarbanilate m -methylcarbanilate (phenmedipham) and two analogues were evaluated in six field studies. Phenmedipham at 1.7 kg/ha controlled foxtail millet ( Setaria italica (L.) Beauv.) and kochia ( Kochia scoparia (L.) Schrad.) better than 2.2 kg/ha of methyl m -hydroxycarbanilate carbanilate and ethyl m -hydroxycarbanilate carbanilate. Pigweed ( Amaranthus spp.) was controlled better by the analogues at 1.1 kg/ha than by phenmedipham. The foliar growth of sugarbeets was generally suppressed more by the analogues than by phenmedipham, but injury was not considered detrimental at 1.1 kg/ha. Yield of sugarbeet roots and sugar was reduced by 7% or less by phenmedipham at rates of 1.1 to 4.5 kg/ha, but these yield reductions were associated primarily with the failure of phenmedipham to completely control all weeds for 5 to 9 weeks after treatment.