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The systemic insecticides phorate, formerly designated as Thimet® (O,O-diethyl S-(ethylthio)methyl phosphorodithioate), Di-Syston® ((O,O--diethyl S-2-(ethylthio)ethyl phosphorodithioate) and demeton were evaluated in a series of field trials for control of the green peach aphid, Myzus persicae (Sulz.), the leafhopper, Empoasca filamenta DeL., and the tobacco flea beetle, Epitrix hirtipennis(Melsh.) on potatoes. The three insecticides were applied on activated charcoal to cut potato seed pieces. Granulated phorate and Di-Syston were applied to the soil with the seed pieces or with fertilizer at planting time. Demeton was also applied to cut seed pieces as a 0.75% emulsion dip. The charcoal seed piece treatments with phorate 44% and Di-Syston 50% at 2.6 ounces of formulated material per 100 pounds of seed pieces provided good control of the green peach aphid for 77 days. Applications of 2% phorate granules or 2% Di-Syston granules at 100 pounds per acre in the seed furrow controlled the green peach aphid for 86 days. Di-Syston generally gave longer aphid control than phorate. The demeton dip was more effective than the charcoal formulation in controlling the green peach aphid but in general control was poor. Seed piece treatments with carbon formulations of phorate and Di-Syston were not as effective as applications of granules in controlling filamenta. Applications of phorate or Di-Syston granules gave excellent leafhopper control for 97 to 100 days. The two materials appeared to be about equal in effectiveness. Demcton failed to control this leafhopper. The tobacco flea beetle was better controlled with seed piece treatments of charcoal formulated phorate and Di-Syston than with granules. Phorate resulted in slightly better control than Di-Syston. Charcoal formulations of phorate and Di-Syston, especially at dosages of 2.6 ounces per 100 pounds of seed, greatly retarded plant emergence and in some instances reduced stand. Injury was especially severe on potatoes grown in peat soil. Applications of granules had less effect on delaying plant emergence although when applied in the seed furrow some slight reductions in stand resulted. The placing of the insecticide granules in fertilizer bands away from the seed pieces had little or no adverse effect on emerge nee and plant growth. Treating the seed pieces with demeton both as powders and as It dip appeared to stimulate plant growth. Plants from demeton-treated seed pieces emerged ahead of all other treatments. Residue studies with phoratc indicate that applications of this material to seed pieces ro to the soil at planting time leave no detectable residues on the tubers 74 or 91 days later.
Document Type: Research Article
Publication date: October 1, 1960
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Journal of Economic Entomology is published bimonthly in February, April, June, August, October, and December. The journal publishes articles on the economic significance of insects and is divided into the following sections: apiculture & social insects; arthropods in relation to plant disease; forum; insecticide resistance and resistance management; ecotoxicology; biological and microbial control; ecology and behavior; sampling and biostatistics; household and structural insects; medical entomology; molecular entomology; veterinary entomology; forest entomology; horticultural entomology; field and forage crops, and small grains; stored-product; commodity treatment and quarantine entomology; and plant resistance. In addition to research papers, Journal of Economic Entomology publishes Letters to the Editor, interpretive articles in a Forum section, Short Communications, Rapid Communications, and Book Reviews.