Toxic Residues in Soil 9 Years after Treatment with Aldrin and Heptachlor.

In silt loam soil heavily infested with European wireworm, a single treatment with aldrin or hepta chlor prevented reinfestation for 9 years, even when the soil was under continuous cultivation. Toxic residues were determined by bioassay with Drosophila melanogaster Meig. By gasliquid chromatographic analysis, the residues were found to be mainly dieldrin and heptachlor epoxide.