Residues of Fenthion and Five of its Metabolites: Their Persistence in Corn and Grass Forages12

Coastal bermudagrass and corn treated with fenthion emulsifiable concentrate at 0.5, 1.0, and 2.0 lb per acre and sampled 0, 1, 2, 7, 14, and 21 days posttreatment were analyzed for fenthion and 5 of its metabolites (oxidation products). In the field, extensive oxidation of fenthion to the metabolites (primarily to fenthion sulfoxide) occurred almost immediately. Residues of all 6 compounds were detected in the grass, and residues of 5 compounds (no fenthion oxygen analog) were detected in the corn after various intervals of weathering in the field. Residues of fenthion and the metabolites in corn ensiled in gallon jars were persistent and oxidized at a lower rate in silage than in the field.