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.