Sulfentrazone dissipation in soil was examined in field experiments in 1995, 1996, and 1997 at Knoxville, TN, on a Sequatchie loam soil. Sulfentrazone 50% disappearance time (DT50) varied from 24 to 113 d. Cotton injury was observed the year following sulfentrazone application when half-lives were ≥85 d. Sulfentrazone degradation under controlled laboratory conditions was slower in autoclaved soil than in nonautoclaved surface soil and subsurface soil, with DT50 of 198, 93, and 102 d, respectively. The difference due to autoclaving the soil implied that sulfentrazone degradation was influenced by both microbial and chemical mechanisms.

Sulfentrazone adsorption and mobility in six soils with varying soil properties were evaluated under laboratory conditions. Adsorption was evaluated using a modified slurry technique. Mobility was evaluated using packed-soil columns under saturated flow conditions. The order of adsorption to soil was Sequatchie loam > Dothan loamy sand = Bosket fine sandy loam > Malden loamy sand > Commerce silty clay loam > Harkey clay loam. Greater sulfentrazone adsorption occurred in soils with lower pH. Sulfentrazone movement under saturated flow conditions in 27-cm soil-packed columns was greater in soils with low adsorption, high pH, and coarse texture. Sulfentrazone movement was limited in the Sequatchie loam but was greater in the other soils examined. No clear relationship was evident between sulfentrazone mobility and adsorption in these soils.

A greenhouse experiment was conducted from 1995 to 1996 to determine the inheritance of ALS-cross-resistant common cocklebur. Two known biotypes (ALS-susceptible and ALS-resistant) were used in the experiment. Susceptible biotypes were crossed with pollen from resistant biotypes. F1 plants were self-pollinated. F2 plants were sprayed postemergence (POST) with a tank mixture of imazaquin at 280 g ai/ha and chlorimuron at 18 g ai/ha. Three distinct responses were observed: (1) no apparent effect (resistant), (2) yellowing of leaves with live terminals (intermediate), and (3) yellow leaves with dead terminals (typical symptoms of an ALS-susceptible common cocklebur). Chi-square tests indicated that an incomplete dominance model did not fit the data. Responses one and two were, therefore, combined and chi-square tests indicated a complete dominance model fit the data. This indicates that the cross-resistant trait is a dominant to semidominant trait.

A rapid method for the determination of sulfentrazone in soils is described. The method consists of extraction of soil samples with methanol, filtration, liquid chromatographic separation of methanol-soluble components through a C18 column, and ultraviolet detection at 220 nm. Recoveries from fortified surface soils were >85% for sulfentrazone. Average relative standard deviations over the soils examined was 7.7%. A conservative lower limit of quantitation for sulfentrazone was 40 ng/g soil.