A comparison of the tolerance by winter wheat of herbicide mixtures containing dicamba and 2,3,6‐TBA, or ioxynil

Abstract

Summary: The tolerance by winter wheat of two types of herbicide was examined in field experiments over 3 years. When overdosed or sprayed late, an ioxynil + mecoprop mixture had a greater margin of safety to the crop than mixtures containing dicamba or 2,3,6‐TBA. Herbicide mixtures containing MCPA, applied before the leaf sheaths of the crop began to extend in the spring caused ear deformities. Spraying dicamba mixtures when the crop was jointing resulted in narrowed ears and shrivelled grain, In one experiment the latter effect was produced by a dicamba mixture, at twice the recommended dose, when sprayed on any of ten dates, covering crop development stages from 6‐leaves through to jointing. Varieties differed in their tolerance of the dicamba mixtures; Maris Ranger was most sensitive but part of this difference could have been due to differences in the stage of development of the varieties at the time of spraying.