In laboratory studies, neither germination nor quality of peanuts was adversely affected by fumigation with phosphine, regardless of the dosage or the number of times the peanuts were fumigated. Sorption of phosphine ranged from 55.3 to 71.1% and was highest for peanuts with 7% moisture content. Residues of phosphine generally increased with dosage and the number of fumigations; however, the highest residue (11.3 ppb) occurred after 3 fumigations at the highest dosage (1.12 mg/liter).
Methyl bromide fumigation of peanuts in the laboratory reduced germination and quality in direct proportion to the dosage applied and the number of fumigations. Sorption ranged from 88.8% to 92.9%, was inversely proportional to the dosage, and increased with an increase in moisture content of the peanuts. Also, total bromide residues increased proportionately with the dosage and the number of fumigations. Residues of >200 ppm were found on peanuts after 3 fumigations at the highest dosage tested (64 mg/liter), regardless of the moisture content, and after 3 fumigations at 48 mg/liter on peanuts of 7% moisture content.
When 900-kg (1-short ton) corrugated paper bulk containers were fumigated with phosphine, the gas mat penetrated the containers killed all insects exposed at the center of the peanut mass; there was no effect of phosphine on the germination or quality of the peanuts, and residues of phosphine were well below the tolerance regardless of the dosage or the number of times fumigated. When the containers were fumigated with methyl bromide, the gas that penetrated the containers killed all insects exposed in the center of the mass only at the highest dosage tested (64 mg/liter); germination was reduced, quality decreased with successive fumigations, and residues increased in proportion to the dosage and the number of times fumigated. Unlike the laboratory test, bromide residues exceeded 200 ppm only after 3 fumigations at the highest dosage tested.
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Keywords: phosphine, methyl bromide, Germination, quality, shelled peanuts, gas concentration, sorption, residues, Plodia, Sitophilus, Tribolium.
How to Cite:
Leesch, J. & Gillenwater, H. & Davis, R. & Wilson, R.,
(1979) “Phosphine and Methyl Bromide Fumigation of Shelled Peanuts¹”,
Peanut Science 6(1).