SELECTIVITY OF BENAZOLIN IN CRUCIFERAE

Abstract

The relative response of some economically important Cruciferae genera and species to benazolin (4-chloro-2-oxobenzothiazolin-3-ylacetic acid) was evaluated under field conditions and related to their phylogeny. Of the species examined only wild mustard (Brassica kaber (DC) L. C. Wheeler) showed almost complete susceptibility to benazolin at the 0.56 and 0.84 kg/ha rates of application, although B. nigra (L.) plants were severely damaged. Other related genera and species responded in varying degrees from almost no visible reaction in B. hirta Moench, B. napus L., and Crambe spp., through slight symptoms of leaf curl in B. campestris L., to more pronounced effects in B. juncea (L.) Coss, B. carinata Braun, and Raphanus sativus L. The heavier rate of benazolin application resulted in the greatest differentiation among species. The species reaction to benazolin tended to follow the genome relationship, with the amphidiploids B. juncea and B. carinata being intermediate in tolerance between the putative parent species, B. nigra and B. campestris or B. oleracea L. Differential species response suggests that benazolin may be effective for control of B. kaber in crops of B. hirta and Crambe species.