The herbicidal mode of action of R-40244 and its absorption by plants

The herbicide R-40244, 1-(m-trifluoromethylphenyl)-3-chloro-4-chloromethyl-2-pyrrolidinone, was studied to elucidate its action and absorption by corn (Zea mays L. DeKalb XL-45A) and other plant species. R-40244 readily induced lead chlorosis in susceptible plants at relatively low rates of application. The leaf chlorosis was found to be related to a reduction in chlorophyll and β-carotene content and an accumulation of the β-carotene precursor, phytoene. The phytotoxic action of R-40244 occurred only under light conditions. R-40244 was readily absorbed by plant roots and translocated to foliar tissues. There were no discernible differences in R-40244 absorption between proadleaf and grassy species. However, uptake studies with eight plant species indicated that foliar accumulation tended to occur in susceptible species and root accumulation predominated in tolerant species.