Pesticide Research Journal

The effect of two non-ionic surfactants (Tween-80 and Triton X-100) and a sensitizer (riboflavin) on the rate of photolysis of tribenuron-methyl, a sulfonylurea herbicide, in aqueous solution was studied under sunlight and UV-light. Both the surfactants and the sensitizer significantly enhanced the rate of photodegradation of tribenuron-methyl in HPLC grade water. The calculated half-life values of tribenuron-methyl in water with no surfactant/sensitizer were 18.3 h under UV-light and 30.4 d under sunlight as compared to 1.7, 2.5 and 2.8 h under UV-light and 6.6, 8.4 and 6.8 d under sunlight in water containing Tween-80, Triton X-100 and riboflavin, respectively. The surfactant and carrier used in 10% WP formulation of tribenuron-methyl also enhanced its rate of degradation in nqueous solution with half-life values of 10.7 d in sunlight and 4.1 h in UV-light. The enhancement in the rate of photolysis of tribenuron-methyl in water by Tween-80 than by Triton X-100 may be the resull of photosensitization.