Abstract
Acephate, O, S-dimethyl acethylphosphoramidothioate, was applied to a tobacco leaf and its fate, incorporation and translocation in the leaf were studied. The compound decreased rapidly for 3-7 days after treatment and the concentration reached 1ppm about 2 months later. In the leaves, acephate was metabolized to methamidophos, which was almost entirely accumulated after 7 days. The degradation of acephate applied on a glass plate was less than on a leaf surface. Acephate deposited on a leaf surface was incorporated into the leaf tissue with 22% of the residue after 24 hour and 82% after 7 days. Acephate applied on the left half surface of a leaf moved to the midrib for 2 days and then moved to the right half of the leaf as a metabolite, methamidophos. During the translocation, the concentration of methamidophos in the midrib was low. The translocation of acephate from the bottom half surface of a leaf to the upper portion was quicker than that of horizontal shift. It was also observed that the acephate translocated poorly from one leaf to another.
