ABSTRACT
The rainfastness of thifensulfuron {3-[[[[(4-methoxy-6-methyl-l,3,5-triazin-2-yl)amino]carbonyl]amino]sulfonyl]-2-thiophenecarboxylic acid} and tribenuron {2-[[[[(4-methoxy-6-methyl-l,3,5-triazin-2-yl)methylamino]carbonyl]amino]sulfonyl]benzoic acid} was examined in four pot experiments. The herbicides were applied alone or in a tank mixture with 0.1% (v/v) nonionic surfactant, 1% (v/v) vegetable oil, 1% (v/v) mineral oil concentrate, 2.5% (w/v) ammonium sulfate, 0.025% (v/v) organosilicone surfactant, and 0.5% (v/v) cationic surfactant or 0.15% (v/v) of a synthetic latex. Three mm of rain was applied 2 and 4 h after herbicide application using a rain simulator. The results were analyzed using a parallel-line assay technique.
The phytotoxicity of both herbicides applied alone was reduced significantly by rain 2 and 4 h after spraying. All adjuvants except ammonium sulfate improved the rainfastness of thifensulfuron. Full rainfastness was obtained 2 h after application in a tank mixture with the vegetable oil or the synthetic latex. Only ammonium sulfate and the cationic surfactant did not improve the rainfastness of tribenuron, while the vegetable oil and the organosilicone surfactant gave full rainfastness 2 h after herbicide application.
