Translocation and Metabolism of the Acaricide Fenothiocarb in Citrus

Abstract

The translocation and metabolism of 14C-fenothiocarb [S-(4-[14C(U)] phenoxybutyl) N,N-dimethylthiocarbamate] were studied using citrus such as summer orange seedlings and mandarin orange trees with fruit under greenhouse conditions. Very little 14C-fenothiocarb was translocated when applied on the middle of upper or lower surface of leaf, and its limited translocation to an upward direction was found when applied to stem. When it was sprayed to mandarin orange trees, the initial concentration of radioactivity in the leaves and fruit rinds was 26.3 and 4.7 ppm, respectively. The radioactivity dissipated more rapidly in the leaves than in the rinds with the half-lives of fenothiocarb being estimated 1.6 and 12 days, respectively. The concentration of radioactivity in the edible part of fruit increased with time, but that equivalent to fenothiocarb remained 43 to 46 ppb at the mature stage. Orange juice from the edible part contained water-soluble metabolites. The major metabolites identified in the leaves, rinds and edible fruit were 6-0-malonyl-/3-D-glucoside of N-hydroxymethyl-fenothiocarb, N-formyl-fenothiocarb and glycoside conjugates of phenol, respectively. The minor ones were identified as fenothiocarb sulfoxide, N-hydroxymethyl-fenothiocarb, monodesmethyl-fenothiocarb and 4'-hydroxy-fenothiocarb.