How to Manage Pests
UC Pest Management Guidelines
Green Peach Aphid
Scientific Name: Myzus persicae
(Reviewed 1/09, updated 4/10, pesticides updated 4/16)
In this Guideline:
DESCRIPTION OF THE PEST
Green peach aphid is most common in spring and fall but may be found at any time throughout the year. It is a medium-sized aphid and the wingless forms are uniformly pale green in color. At times, a pinkish form may be present. During cool weather, individuals of both color forms may be slightly darker than those found during hotter times of the year. Both winged and wingless forms have prominent cornicles that are slightly swollen and clublike in appearance. The frontal tubercles at the base of the antennae are very prominent and are convergent. The winged forms have a distinct dark patch on the top of the abdomen; wingless forms lack this dark patch.
The green peach aphid vectors more plant viruses than any other aphid, transmitting over 100 different virus diseases. It does not, however, vector Carrot motley dwarf virus or Carrot red leaf virus. Aphid-infested leaves are distorted and curled. If populations are high enough, stunting may occur. Infestations on young plants are more serious than those on older plants.
Green peach aphid is attacked by a number of common predators and parasites and is susceptible to the fungus disease that commonly attacks aphids. Common predators include green lacewing, lady beetles, and syrphid fly larvae.
Field sanitation is important in reducing the number of aphids in and around carrots.
Organically Acceptable Methods
Biological and cultural controls are acceptable for use on organically grown produce.
Monitoring and Treatment Decisions
Monitor fields for aphids weekly during spring and summer by examining the upper and lower surfaces of leaves. Also, look for evidence of predators and parasites and their impact on aphid populations. Small colonies occasionally develop on carrot leaves and may reach treatable levels, but no treatment thresholds for green peach aphid on carrots have been established. Green peach aphid has developed a high level of resistance to many chemicals and may be hard to control.
UC IPM Pest Management Guidelines: Carrot
E. T. Natwick, UC Cooperative Extension, Imperial County
Acknowledgment for contributions to Insects:W. E. Chaney, UC Cooperative Extension, Monterey County