Control of Avena fatua L. and Cirsium arvense (L.) Scop. with mixtures of 3,6‐dichloropicolinic acid and four herbicides for control of A. fatua

Abstract

SummaryControl of Avena fatua (L.) (wild oat) with diclofop methyl applied at 0·7 kg ha−1 at the two‐leaf stage and difenzoquat at 0·84 kg ha−1 at the four‐leaf stage in wheat (Triticum aestivum L.) under field conditions was good and not affected when either of these herbicides was mixed with 3,6‐dichloropicolinic acid as the monoethanolamine salt at 0·14, 0·20 or 0·30 kg ha−1. In the glasshouse, mixtures containing 3,6‐dichloropicolinic acid at rates as high as 0·6 kg ha−1 also did not affect control of A. fatua. When barban at 0·35 kg ha−1, or flamprop methyl at 0·56 kg ha−1 was mixed with similar rates of 3,6‐dichloropicolinic acid and applied at the two‐leaf and four‐leaf stage of A. fatua respectively, a reduction in control of A. fatua (antagonism) occurred under both field and glasshouse conditions. The herbicides for control of A. fatua did not influence the fresh weight suppression of C. arvense shoots obtained in the glasshouse with 3,6‐dichloropico‐colinic acid at 0·3 kg ha−1. Early tolerance of wheat (cv. Neepawa) was acceptable with all mixtures. Wheat yields with diclofop methyl or difenzoquat alone or in mixture with 3,6‐dichloropicolinic acid were increased over the yields from the A. fatua‐infested control.