Differential cultivar tolerance to herbicides in crops has been recognized for years (Barrentine et al. 1976, 1982; Graf and Ogg 1976; Harrison et al. 1985; Shaw and Wesley 1991; Stephenson et al. 1976). Until recently, however, few attempts have been made to consciously develop cultivars with improved herbicide tolerance. There was an effort in soybean [Glycine max (L.) Merr.] to develop cultivars with better tolerance of metribuzin [4-amino-6-(1,1-dimethylethyl)-3-(methylthio)-1,2,4-triazin-5(4H)-one]. The cultivar ‘Tracy M’ 214was developed as part of this effort (Barrentine et al. 1982; Hartwig et al. 1980).