Abstract
The residual effect of DDT, endosulfan, and parathion applied at various rates and intervals prior to certain harvests of cigar-wrapper tobacco was studied in 1965. Residues on the cured and fermented leaves were determined by gas chromatography or colorimetric methods. Recovery of known amounts of DDT, endosulfan, and parathion added to untreated tobacco ranged from 89 to 100%, 75 to 97%, and 31 to 77%, respectively. Mean residues in ppm by harvests ranged from 125.0 to 303.3 for DDT, 18.4 to 33.1 for endosulfan, and 2.5 to 4.9 for parathion. The effect of weathering in the field was inconsequential in reducing residues because of the frequency of insecticide applications during the growing season. High residues of all 3 insecticides are inevitable if effective insect control is maintained by their use.
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