Chlorpyrifos-methyl as a Protectant of Farmers Stock Peanuts1

Abstract

Abstract Runner variety farmers stock peanuts were treated with either distilled water, 52 ppm malathion. or chlorpyrifosmethyl (CM) applied at 10, 15, 20 and 25 ppm, held in a metal shed and artificially infested with insect pest species commonly found in stored peanuts. Peanuts were sampled at 2, 4, 6, 9 and 12 months post-treatment. After 6 months ca 22% of loose-shelled kernels (LSK) in malathion-treated peanuts were damaged by insects; after 9 and 12 months damage increased to 36 and 49%. In contrast, LSK damage in peanuts treated with CM exceeded 6% after 9 and 12 months only in the 10 ppm treatment. Damage to kernels from cracked pods in malathion-treated peanuts was 6.9 and 11.2% after 9 and 12 months, respectively, but damaged cracked pod kernels exceeded 2% only in the 10 ppm CM treatment at 12 months. Degradation of CM residues occurred more slowly than malathion residues during the final 6 months of the test.