Residues of Lorsban (Chlorpyrifos and Its Trichloro-2-Pyridinol Metabolite) in Collards When Applied for Control of Root Maggot, 1981

Lorsban 4E formulation was applied to collards at the rates of 1.6 and 3.2 fl oz (AD/1000 ft row at the Yakima research station and the Beltsville research station. At Yakima, the formulation was sprayed over the row at planting time, in front of the plant shoe, for shallow incorporation into the soil on 20 May 1981, and again as a direct spray at the base of the plants on 8 July. At Beltsville, the formulation was applied as a drench to each plant one day after the plants had been transplantd ln(x+l) for % leaf area mined andcations of each treatment. The laboratory procedure used for sampling, extraction, and cleanup of extract is available on request.