In laboratory tests, only 8-13% survived of lst-instar nymphs of the green peach aphid (GPA), Myzus persicae (Sulzer), placed on young lambsquarters, Chenopodium album L., and redroot pigweed, Amaranthus retroflexus L., with 2-4 leaves initially and held to adult stage. GPA had 80% survival and shorter developmental time on radish, Raphanus sativus L., shepherdspurse, Capsella bursa-pastoris (L.) Medik, field bindweed, Convolvulus ar-venis L., hoary cress, Cardaria draba (L.) Desv., yellowflower pepperweed, Lepidium per-foliatum L., and hairy nightshade, Solarium sarrachoides Sendt. When life table statistics were determined for the 7 weed plants and radish, hoary cress had the highest intrinsic rate of increase, r = 0.401; and mat for radish was r = 0.357. In field cage experiments, with plants with 6 true leaves initially, the GPA multiplied faster on shepherdspurse, radish, and hairy nightshade than other weeds. In the orchard, the GPA population in late May on 6 common weed species ranged from 608/pigweed plant to 4659/yellowflower pepperweed plant. Winged migrants contributed from 3.8-26% of these populations and the estimated production of winged GPA was 70 million migrants/ha. Since about half of these orchard weed species are known hosts of beet western yellow virus (BWYV), many of the winged GPA from the orchard weeds are potential vectors of BWYV. © 1979 Entomological Society of America.
