Selectivity of Dicamba in Wheat and Wild Buckwheat

The uptake, translocation, and fate of14C-labeled 3,6-dichloro-o-anisic acid (14C-dicamba) were studied in wheat (Triticum aestivumL., 'Selkirk’) and wild buckwheat (Polygonum convolvulusL.) as resistant and susceptible species, respectively. Selectivity could not be explained by interspecific differences in uptake of14C-dicamba by leaf sections submerged in exogenous solutions.14C-dicamba accumulated in meristems of wild buckwheat but not in the youngest tillers of wheat. Moreover, wheat main culms conjugated or metabolized14C-dicamba more quickly than did wild buckwheat meristems. Therefore, selectivity of dicamba apparently was related to interspecific differences in translocation and metabolism.