Abstract
The degradation of the sulfoxide of fenothiocarb (S-4-phenoxybutyl N, N-dimethylthiocarbamate), an acaricide for the control of citrus red mites, was studied in Okitsu alluvial and Ibaraki volcanic ash soils under upland conditions using [phenoxy-U-14C]-preparation. Fenothiocarb sulfoxide disappeared very rapidly, with its residue in both soils less than 1% of the applied dose 7 days after treatment. Radioactivity in aqueous methanol extracts, evolved 14CO2, and bound 14C-residues were 48.7, 5.3 and 44.7% in Okitsu soil, and 24.8, 6.9 and 69.6% in Ibaraki soil, respectively. In both soils, the evolution pattern of 14CO2 was similar and the formation of bound residues was relatively high especially so in Ibaraki volcanic ash soil. Methyl 4-phenoxybutylsulfone, bis(4-phenoxybutyl)thiolsulfinate, methyl 4-phenoxybutylsulfoxide and 4-phenoxybutylsulfonic acid were identified as major degradation products in both soils. Fenothiocarb, bis(4-phenoxybutyl)disulfide and phenoxyacetic acid were also identified as relatively minor products. Fenothiocarb sulfoxide disappeared much faster than fenothiocarb, and the fenothiocarb sulfoxide-treated soils formed more bound residues.
