A residue study of permethrin on tomato plants

A study of permethrin residues on tomato plants was undertaken with the use of a gas chromatograph-mass spectrometer. Sixty tomato piants (Cv. Walter) were arranged in a randomized complete block replicated four times. Applications evaluated were 0.0 1b per acre, 0.1 lb per acre, and 0.2 lb per acre. Leaf samples were collected at various intervals over a two week period. After solvent partitioning and adsorption column cleanup procedures, the samples were analyzed by using a gas chromatograph-mass spectrometer operating in the selected ion monitoring mode.

The results of this study showed that permethrin residues underwent rapid decline during the first two to three days after application, declined at a much slower rate thereafter, and did not seem to be affected by the incidence of rain. This study indicated that increased spray concentrations would not greatly increase the persistence of the insecticide. Permethrin should pose little threat to field workers due to its rapid loss and its low toxicity to mammals. Is has an expected reentry time of approximately 2h hours.