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PERSISTENCE AND EVALUATION OF EPTC AND BUTYLATE ENHANCED DEGRADATION
Abstract
EPTC (S-ethyl dipropyl carbamothioate) degradation rate was enhanced in Clay Center (Crete silty clay loam, pH 6.6, 2.7% O.M.) and Scottsbluff (Tripp very fine sandy loam, pH 8.0, 1.0% O.M.) soils following three annual EPTC, butylate S-ethyl bis(2-methylpropyl)carbamothioate , or vernolate (S-propyl dipropylcarbamothioate) applications, or when rotated biennially with butylate. EPTC degradation was not enhanced following three annual atrazine 6-chloro-N-ethyl-N-(1-methylethyl)-1,3,5-triazine-2,4-diamine , alachlor 2-chloro-N-(2,6-diethylphenyl)-N-(methoxymethyl)acetamide , cyanazine 2- 4-chloro-6-(ethylamino)-1,3,5-triazin-2-yl amino -2-methylpropanenitrile , cycloate (S-ethyl cyclohexylethylcarbamothioate), or metolachlor 2-chloro-N(2-ethyl-6-methylphenyl)-N-(2-methoxy-1-methylethyl)acetamide applications, or when rotated biennially with cyanazine, cycloate, or alachlor. EPTC degradation was not affected in Scottsbluff soil following three annual carbofuran (2,3-dihydro-2,2-dimethyl-7-benzofuranyl methylcarbamate) applications, but was partially enhanced in Clay Center soil. The reversion rate of soil enhanced for EPTC degradation was gradual and varied with location, year, and number of prior EPTC applications. Butylate degradation was normal or only partially enhanced in soil previously treated with EPTC compared to previously untreated soil and soil previously treated with butylate. Self- and cross- enhanced degradation of EPTC and butylate did not change regardless of number of prior annual applications of either herbicide. The degradation rates of EPTC and butylate were not affected by pretreating soil with butylate sulfone, but were enhanced by pretreating soil with the sulfoxides of each herbicide. Rotation of EPTC + dietholate; (O,O-diethyl O-phenyl phosphorothioate) and EPTC + fonofos (O-ethyl S-phenyl ethylphosphonodithioate) in soils with three prior annual treatments of each combination did not improve weed control compared to continuous use. SC-0058 S-ethyl di-(3-chlorallyl) thiocarbamate was effective in slowing EPTC degradation in soils pretreated with EPTC, EPTC + dietholate, EPTC + fonofos, or EPTC + SC-0058. Dietholate was effective in slowing EPTC degradation in soil pretreated with EPTC + SC-0058. SC-0058 appeared to have an inhibitory influence on initial enhancement for EPTC degradation. Dietholate and SC-0058 did not condition the soil for their own enhanced degradation after repeated use. The extenders were more effective inhibitors of enhanced EPTC degradation in soil from Scottsbluff than from Clay Center.
Subject Area
Agronomy
Recommended Citation
BEAN, BRENT W, "PERSISTENCE AND EVALUATION OF EPTC AND BUTYLATE ENHANCED DEGRADATION" (1986). ETD collection for University of Nebraska-Lincoln. AAI8629525.
https://digitalcommons.unl.edu/dissertations/AAI8629525