Dicamba use and Injury on Soybeans(Glycine max)in South Dakota

Field experiments were conducted from 1974 to 1977 at Redfield and Centerville, South Dakota, to evaluate the tolerance of soybeans [Glycine max(L.) Merr.] at different growth stages and five varieties of soybeans to dicamba (3,6-dichloro-o-anisic acid) and to determine dicamba residue in the foliage. Yield reduction occurred from applications when soybeans were flowering. Furthermore, germination was reduced by dicamba application at pod-fill. Dicamba residue was detected in foliage 7 days but not 18 days after application. Extent of dicamba use and drift occurrence was determined by a telephone survey of 159 farmers. Thirty-one percent of the farmers surveyed used dicamba in 1976.