ABSTRACT
Dicamba is completely metabolized by wheat plants in 18 d to form a major metabolite, 5-hydroxy-2-methoxy-3,6-dichlorobenzoic acid (Fig. 8.4), and a minor metabolite, 3,6-dichlorosalicylic acid, w i t h the major metabolite accounting for 90% of the radioactivity and the minor metabolite for 5% [6]. Ray and Wilcox [68] found that maize roots also converted dicamba into 5-hydroxy derivative as the major metabolite and 3,6-dichlorosalicylic acid as the minor metabolite. Wheat and barley alter the dicamba molecule more extensively than buckwheat and w i l d mustard (Sinapis arvensis) [14]. Ray and Wilcox [69] detected no dicamba metabolism in Cyperus rotundus even after 10 d. Quimby and Nalewaja [66] observed more rapid metabolism of dicamba in wheat, a resistant species, than i n w i l d buckwheat, a susceptible species. Thus, differ ential transformation of dicamba is apparently related to species selectivity.
