Several researchers have shown formulation can affect washoff of pyrethroids in studies involving small test systems, in some cases by more than two orders of magnitude. To determine the effect of formulation under actual use conditions, replicated studies were conducted at a full scale test facility. Five pairs of different products (both products contained the same active ingredient in four of these pairs) were examined. Four of these pairs were applied as broadcast applications to sloped driveway and the other pair was applied to a portion of the house wall next to the driveway. The differences within each of the five pairs did not exceed a factor of five, compared to ratios of up to 170 in an indoor simulator. For one pair, one formulation had lower washoff in the laboratory, but higher washoff in the field. This study shows the effect of formulation is real, but complex, and the differences under actual outdoor use conditions are smaller than observed in laboratory studies.

Effect of formulation on pesticide runoff losses under field conditions

248th National Meeting (2014)

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