Movement and metabolism of phorate under field conditions after granular band applications.

Phorate residues moved in both vertical and horizontal directions after a granular band application of the insecticide at 5 and 10 lb/acre. This was determined by analyses of horizontal and vertical soil cores collected 4½ months after soil treatment 2 to 4 in. away from the original band. Extracts of these soils were all toxic to Drosophila melanogaster Meigen, indicating that insects could still be controlled 2 to 4 in. away from the place of the original phorate deposit. Contrary to findings with emulsifiable concentrates, phorate persisted for a relatively long period. Eight to 60% of total residues recovered from soil samples collected through the band were still in the form of phorate. Metabolism of phorate was most pronounced in the 5 lb/acre-treated soil and was relatively slower in the 10 lb/acre-treated soil. Phorate sulfone was the major component in all soil cores collected from the 5 lb/acre-treated soil, but only in soil cores collected below the original band treated at 10 lb of actual phorate/acre. The relative composition of vertical soil cores collected through the band (5 lb/acre applied) and 2 in. away from it was phorate sulfone > phorate sulfoxide > phorate, while in cores from the 10 lb/acre treated soil this composition was phorate > phorate sulfone > phorate sulfoxide.