Arbitrary green peach aphid, Myzus persicae (Sulzer), action thresholds (0, 5, 10, 20, and 40 aphids per 100 leaves) were tested in 3 yr of field experimentation to determine if they could be maintained and if they would significantly impact aphid densities and limit the incidence of potato leafroll virus (PLRV). In 1997 and 1998, significant linear relationships between thresholds and final percentage of PLRV (expressed as the percentage of tubers infected with PLRV) were observed; there was a trend toward lower PLRV incidence with decreasing action threshold in 1999. There were significant relationships between thresholds and mean number of apterous aphids in 1998 and 1999, indicating that reduction of PLRV resulted from reduced within-field spread by apterae. In almost all cases, aphid densities exceeded threshold levels from one week to the next, clearly showing that the thresholds could not be maintained. Over all experiments, four to nine seasonal applications of methamidophos were warranted by the magnitude of the threshold. Imidacloprid applied at planting to the zero aphid threshold reduced the number of methamidophos applications from nine in the insecticide-at-detection treatment to five. A revised within-field green peach aphid management plan is recommended that includes systemic insecticide applied at planting, aphid sampling every 3–4 d, and foliar insecticide application following aphid detection.
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.