Loss of Fluometuron in Runoff Water

Abstract

AbstractThe amount of fluometuron [1,1‐dimethyl‐3‐(α,α,α‐trifluoro‐m‐tolyl)urea] in runoff water under different environmental conditions was determined in the southern U.S. and Puerto Rico. In Mississippi, Puerto Rico, and Texas, runoff water was collected from soil sprayed with 4.4 kg/ha of fluometuron each year for 3 years. Tests were conducted in Tennessee for 2 years and in North and South Carolina for 1 year. Water samples were collected in 4‐ by 10‐m plots, and 1 m downslope. Initial runoff was produced with sprinkler irrigation immediately after herbicide application at all locations except Tennessee and South Carolina which relied on rainfall. Later in the season, water was sampled from two additional runoff events of either irrigation or rainfall. A total of 32 runoff events were sampled at the 6 locations. The level of fluometuron in water caught 1 m downslope from treated areas during the first runoff averaged 0.30 ppm and was highest (0.87 ppm) in Puerto Rico. Fluometuron concentration in subsequent events was much lower than in the first runoff events. Average loss of fluometuron in 1 cm of runoff was <1% of applied fluometuron. Only 2% of applied fluometuron was lost in the situation producing the highest concentration in runoff water. Level of fluometuron in runoff water was directly related to slope. Results of this study indicate that fluometuron concentrations in runoff from treated fields are such that nontarget species should not be adversely affected.