Abstract
Deltamethrin was applied to a sandy clay loam at 17.5 g/ha in an indoor incubation study and in 2 field experiments. Residues were monitored for up to 52 wk using a 63Ni-electron capture GC [gas chromatography] method. Method recoveries were 91.1-99.6% at fortification levels of 1-100 ppb. Indoors, deltamethrin declined exponentially with a half-life of 4.9 wk. In the field, the half-life was 6.9 wk with 5-7% of the applied deltamethrin remaining after 52 wk. There was no evidence of residue mobility under field conditions. The difference in the rate of residue decline between indoor and field experiments was attributed to climatic effects. A deltamethrin isomer, (.alpha.R)-deltamethrin, was present in soil extracts in small amounts.