Bentazon Translocation and Metabolism in Soybean and Navy Bean

Abstract

Following foliar application of 14 C-bentazon [3-isopropyl-1 H -2,1,3-benzothiadiazin-(4)3 H -one 2,2-dioxide], a promising selective postemergence herbicide for the control of broadleaf weeds in soybean [ Glycine max (L.) Merr.] and navy bean ( Phaseolus vulgaris L.), the movement of the 14 C-label was primarily acropetal in both species, with some basipetal movement. Metabolism was more rapid in the trifoliate navy bean leaf than in the unifoliate navy bean leaf and the trifoliate soybean leaf. Prior treatment with several other herbicides did not decrease metabolism of bentazon in navy bean. The metabolites in navy bean and soybean appeared similar. Four apparent 14 C-conjugates were isolated from soybean plants harvested at full maturity.