How to Manage Pests

UC Pest Management Guidelines

Carrot

Green Peach Aphid

Scientific Name: Myzus persicae

(Reviewed 1/09, updated 4/10)

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.

DAMAGE

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.

MANAGEMENT

Biological Control

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.

Cultural Control

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.

Common name Amount per acre** R.E.I.‡ P.H.I.‡
(example trade name)   (hours) (days)

  Calculate impact of pesticide on air quality
 
The following are ranked with the pesticides having the greatest IPM value listed first—the most effective and least harmful to natural enemies, honey bees, and the environment are at the top of the table. When choosing a pesticide, consider information relating to air and water quality, resistance management, and the pesticide's properties and application timing. Not all registered pesticides are listed. Always read the label of the product being used.
 
A. IMIDACLOPRID
  (Provado 1.6F) 3.5 fl oz 12 7
  MODE-OF-ACTION GROUP NUMBER1: 4A
  COMMENTS: Thorough, uniform coverage is important for good control.
 
** See label for dilution rates.
+ Restricted entry interval (R.E.I.) is the number of hours (unless otherwise noted) from treatment until the treated area can be safely entered without protective clothing. Preharvest interval (P.H.I.) is the number of days from treatment to harvest. In some cases the REI exceeds the PHI. The longer of two intervals is the minimum time that must elapse before harvest.
1 Rotate chemicals with a different mode-of-action Group number, and do not use products with the same mode-of-action Group number more than twice per season to help prevent the development of resistance. For example, the organophosphates have a Group number of 1B; chemicals with a 1BGroup number should be alternated with chemicals that have a Group number other than 1B. Mode-of-action Groupgroup numbers are assigned by IRAC (Insecticide Resistance Action Committee). For additional information, see their Web site at http://www.irac-online.org/.
* Permit required from county agricultural commissioner for purchase or use.

[Precautions]

PUBLICATION

[UC Peer Reviewed]

UC IPM Pest Management Guidelines: Carrot
UC ANR Publication 3438

Insects

  • E. T. Natwick, UC Cooperative Extension, Imperial County
  • D. R. Haviland, UC IPM Program, Kern County
  • C. G. Summers, Entomology, Kearney Agricultural Center, Parlier
Acknowledgment for contributions to Insects:
  • W. E. Chaney, UC Cooperative Extension, Monterey County

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Statewide IPM Program, Agriculture and Natural Resources, University of California
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