Permethrin Concentration on Cotton Plants, Persistence in Soil, and Loss in Runoff1
- B. R. Carroll,
- G. H. Willis and
- J. B. Graves2
The recently-developed synthetic pyrethroid insecticides appear to have a potential for widespread use in cotton (Gossypium hirsutum L.). Thus, their persistence and movement under field conditions should be evaluated to identify any possible environmental hazards. Permethrin (3-phenoxybenzyl [±]-cis, trans-3-[2,2-dichlorovinyl]-2,2-dimethylcyclopropanecarboxylate) (1:1 cis/trans) was applied to cotton at a rate of 0.112 kg/ha on 10 separate dates each year in August and September of 1976 and 1977. Concentration measurements of the cis and trans isomers on cotton plants and leaf litter, and in soil and runoff (sediment + water) indicated that permethrin disappeared about 3–6 months after the last application, confirming permethrin's relatively short persistence compared with organochlorine insecticides. The ratios of the cis and trans isomers of permethrin on plants and leaf litter were near unity, but the concentration of the cis isomer usually was greater than the trans isomer in soil. Under a wide range of rainfall and runoff conditions, permethrin concentrations and losses in runoff were low. In 1976, concentrations in runoff did not exceed 0.20 ppb and the total amount recovered in runoff (water + sediment) was <0.01% of the amount applied. In 1977, an abnormally high rainfall year, concentrations in runoff were generally < 1 ppb, and the total amount recovered in runoff (water + sediment) was < 1% of that applied. Thus, even under severe runoff conditions permethrin concentrations generally were not great enough to be harmful to aquatic species.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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