Following foliar application of14C-bentazon [3-isopropyl-1H-2,1,3-benzothiadiazin-(4)3H-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 vulgarisL.), the movement of the14C-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 apparent14C-conjugates were isolated from soybean plants harvested at full maturity.

The trifoliate leaf of tolerant navy bean (Phaseolus vulgarisL.) retained less bentazon [3-isopropyl-1H-2,1,3-benzothiadiazin-(4)3H-one 2,2-dioxide] from foliar applications than the unifoliate leaf, or the leaves from susceptible cocklebur (Xanthium pensylvanicumWallr.) and moderately susceptible black nightshade (Solarium nigrumL.) seedlings. The14C from14C-bentazon applied to the foliage of black nightshade moved throughout the entire plant. In cocklebur, the14C moved throughout the treated leaf, whereas, in the trifoliate leaf of navy bean, very little acropetal movement occurred from the site of application. However, in the unifoliate leaf of navy bean, acropetal and basipetal movement of14C from the leaf was observed. The species differed in the14C-metabolites formed from14C-bentazon 1 and 5 days after treatment. The rapid metabolism of bentazon in the trifoliate leaf of navy bean appears to be related to tolerance.

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INDEX WORDSBeta vulgaris, sugarbeet, adventitious shoots, benzyladenine SUMMARY Benzyladenine (BA) at concentrations from 33-2000 mg/l caused development of adventitious shoots on subsequent leaves of sugarbeet plants when sprayed once onto cotyledon-stage seedlings. Cultivar EL44 produced more adventitious shoots and greater fresh weight reduction in response to BA treatment than cultivar EL40. Related anomalies caused by BA included dissected leaves, and bumps and rods on petioles.

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