Phytotoxicity of Fluometuron and Its Derivatives to Cotton and Weeds

Abstract

The phytotoxicity of 1,1-dimethyl-3-(α,α,α-trifluoro-m-tolyl)urea (fluometuron) and three of its analogs was studied on cotton (Gossypium hirsutumL.), foxtail (Setariasp.), and redroot pigweed (Amaranthus retroflexusL.). Fluometuron was the most active compound, and the demethylated derivative and aniline analog were the least phytotoxic. The activity of the monomethyl analog of fluometuron, when applied via nutrient solution and to clay soil, was about 50% and 70% of the parent compound, respectively. Photosynthesis in cotton and redroot pigweed was inhibited by fluometuron, to a lesser degree by the monomethyl analog, and not at all by the demethyl and aniline analogs. Cotton was most tolerant, and only slight differences were found between the susceptibility of foxtail and redroot pigweed. These differences in response to fluometuron and its metabolites may contribute to the differential response between cotton and weeds.