| ield and laboratory studies were conducted to evaluate the persistence of pesticides used in rice production. In an in-situ, subsoil dissipation study conducted on a Crowley silt loam, the dissipation rates of benomyl, carbofuran, thiobencarb and triclopyr decreased as depth in the soil increased. Pesticide leaching in this study was minimal due to low K;A laboratory study was conducted to evaluate the stability of thiobencarb, carbofuran, molinate, triclopyr and 2,4-D in water and on C;Another study was conducted to evaluate dissipation of triclopyr and 2,4-D in (1) paddy-rice water and soil, (2) dryland-rice soil, and (3) on bareground. Triclopyr and 2,4-D applied at the panicle differentiation stage of rice growth dissipated in paddy water to levels below detectability by 35 d after application, although both herbicides were slightly more persistent in dryland-rice soil and on bareground. 2,4-D was more commonly detected in sub-soil samples than was triclopyr; although it was not clear if these detections were because of greater mobility or a result of contamination from the surface soil. A laboratory study was conducted concurrently to compare the herbicides relative sorption and mobility in soil. These laboratory studies indicated that triclopyr sorption was slightly greater than 2,4-D sorption, but mobility was not significantly different in hand-packed columns or on soil TLC plates.;A field study was conducted to evaluate the persistence of carbofuran and molinate in paddy-rice culture after post-flood applications. Carbofuran was not detected beyond 28 d after application in paddy water and soil half-lives were... |
