Green peach aphid - Myzus persicae (Sulzer)
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In the spring, as the first leaves appear, green peach aphid (GPA) nymphs appear and begin to feed
on flowers, young foliage, and stems. Large numbers of GPA can develop quickly on new terminal
growth, causing leaves to curl, turn yellow, and wilt or drop from the tree. Aphids also produce
honeydew and can be a vector of viral diseases such as plum pox. Chemical treatment for GPA in
July may not be needed because GPA produces a winged generation in July that migrates to summer
host plants, returning to tree fruit hosts in the fall to overwinter.
Monitoring and thresholds: GPA prefer to feed on the underside of leaves. Starting at petal fall until
about 1 month after shuck fall, examine 50 spurs from 10 trees (5 spurs/tree) weekly. Focus early
efforts on root suckers or on leaves in the lower center of trees.
Treat if there are more than 30-50% infested terminals on peach (mature, vigorous trees can withstand
higher pressure than young trees); 1 colony/tree on nectarine. Monitor also for the presence of GPA
predators (e.g., larvae of ladybird beetles, lacewings, and syrphid flies). Large numbers of these
predators can help control aphid populations, delaying or eliminating the need for a chemical control.
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Injury on nectarine.
First spring generation adults are
wingless, about 1.7 to 2.0 mm long,
and yellow-green with two lateral
green stripes on their abdomen and
two moderately long cornicles
(tailpipes) on the end of the abdomen.
Stem mothers are a deep pink color.
Additional information
For more monitoring information and evaluation of available pesticides:
Michigan Fruit Management Guide
MSU Diagnostic Services for assistance in pest identification.
MSU Fruit Crop Advisory Team Alert newsletters for current pest/crop conditions.
This information was developed from A Pocket Guide for IPM Scouting in Stone Fruits by David Epstein, Larry J. Gut, Alan L.
Jones and Kimberly Maxson-Stein. Purchase this in a pocket-sized guide for reference in the orchard from MSU Extension
(publication E-2840).