EFFECT OF CONSECUTIVE TREATMENTS OF ALDRIN AND HEPTACHLOR ON RESIDUES IN RUTABAGAS AND CARROTS AND ON CERTAIN SOIL ARTHROPODS AND YIELD

Abstract

Aldrin or heptachlor at 5 and 10 lb per acre were each incorporated into a sandy loam for 3 successive years. On a total weight basis, rutabagas grown on treated soil were found at harvest to contain up to 0.02 p.p.m. of aldrin, 0.06 p.p.m. of dieldrin, 0.01 p.p.m. of heptachlor, and 0.03 p.p.m. of heptachlor epoxide; carrots up to 0.15 p.p.m. of aldrin, 0.15 p.p.m. of dieldrin, 0.26 p.p.m. of heptachlor, and 0.04 p.p.m. of heptachlor epoxide. Significant off-flavors were noted in raw carrots after 3 years of soil treatment with the higher rate of heptachlor but not a year later when the insecticide was not applied.Treated plots produced significantly higher yields of beans and carrots than untreated check plots only in the first year of treatment. The increases were attributed to the control of injurious soil insects. Both insecticides gave significant control of cabbage maggot throughout the experiment. Soil mites were reduced in number after the first year of treatment but numbers of Collembola in the soil were not significantly affected.