Basis for differential susceptibility of rice (Oryza sativa), wild rice (Zizania palustris), and giant burreed (Sparganium eurycarpum) to bentazon.

The basis for differential susceptibility of tolerant rice, susceptible wild rice (Zizania palustris) and susceptible giant burreed (Sparganium eurycarpum) to foliar application of 1.1 kg [14C]bentazone/ha was investigated. Giant burreed and wild rice absorbed more bentazone than rice at similar growth stages. Less than 10% of the absorbed bentazone was translocated out of the treated leaf of any of the species. Differential tolerance of bentazone among the 3 species was due to differences in the rate of bentazone metabolism. Rice metabolized 98% of the bentazone retained in the treated leaf 1 day after treatment (DAT), while giant burreed and wild rice metabolized less than 2% of the bentazone retained in the treated leaf 5 DAT.