Sulfentrazone Dissipation in a Tennessee Soil¹

Abstract

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.Nomenclature: Glyphosate, isopropylamine salt of N-(phosphonomethyl)glycine; pyrithiobac, sodium 2-chloro-6-[(4,6 dimethoxy-2-pyrimidinyl)thio]benzoate; sulfentrazone, N-[2,4-dichloro-5-[4-(difluoromethyl)-4,5-dihydro-3-methyl-5-oxo-1H-1,2,4-triazol-1-yl]phenyl]methanesulfonamide; soybean, Glycine max (L.) Merr. ‘Asgrow 5601’; cotton, Gossypium hirsutum L. ‘Paymaster 1220RR’.Additional index words: Degradation, half-life, HPLC.Abbreviations: DAT, days after treatment; DT50, 50% disappearance time; HPLC, high performance liquid chromatography; WAT, weeks after treatment.