METABOLIC-FATE OF INSECTICIDE PYRACLOFOS IN CABBAGE PLANTS

Metabolic fate of pyraclofos, 1-(4-chlorophenyl)pyrazol-4-yl ethyl S-p ropyl phosphoro-thiolate (Voltage), in cabbage plants was studied unde r laboratory conditions using C-14-pyraclofos labeled at the benzene r ing. When C-14-pyraclofos was applied to the leaf surface of the plant s at the rate of 2 mu g/cm(2), pyraclofos disappeared from the treated leaf with a half-life of approximately one meek. Thirty days after fo liar application, most of (14)-C-radio-active carbon (C-14) was found in the treated site of the leaves, however, C-14 translocated to the n ontreated portions was a small extent. Major metabolic pathways of pyr aclofos in cabbage leaves were cleavage of P-O-aryl bond to yield 1-(4 -chlorophenyl)-4-hydroxypyrazole, and followed by conjugation with sug ars such as glucopyranoside or malonylglucopyranoside. A small amount of the parent compound mas detected in the treated site, but not in th e nontreated portions of the leaves. When cabbage plants were cultivat ed for 30 days using soils treated with C-14-pyraclofos at the rate of 10 ppm, most of the C-14 was found in the treated soil. A small amoun t of C-14 was translocated to the plants, and most of it was in the ro ots. On the other hand, C-14 detected from the edible portion, leaf an d stem was very small extent, and no parent compound was determined.