The Basis for Bentazon Selectivity in Navy Bean, Cocklebur, and Black Nightshade

Abstract

The trifoliate leaf of tolerant navy bean ( Phaseolus vulgaris L.) retained less bentazon [3-isopropyl-1 H -2,1,3-benzothiadiazin-(4)3 H -one 2,2-dioxide] from foliar applications than the unifoliate leaf, or the leaves from susceptible cocklebur ( Xanthium pensylvanicum Wallr.) and moderately susceptible black nightshade ( Solarium nigrum L.) seedlings. The 14 C from 14 C-bentazon applied to the foliage of black nightshade moved throughout the entire plant. In cocklebur, the 14 C 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 of 14 C from the leaf was observed. The species differed in the 14 C-metabolites formed from 14 C-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.