How to Manage Pests

UC Pest Management Guidelines

Carrot

Crown and Root Aphids

Scientific Names:
Hawthorn/parsley aphids: Dysaphis foeniculus and D. apiifolia
Tulip bulb aphid: D. tulipae
Hawthorn carrot aphid: D. crataegi

(Reviewed 1/09, updated 1/09)

In this Guideline:


DESCRIPTION OF THE PESTS

These aphids form colonies near the top of the root and at the base of the stems. They occasionally form colonies on the root slightly below ground. All are similar in appearance, with the wingless forms being pale yellow to gray green in color and covered with a powdery wax. The tulip bulb aphid is covered with a white waxy powder, while the wax covering the hawthorn parsley aphid is grayish white. The hawthorn carrot aphid is yellowish gray to greenish gray with a very light dusting of wax. All three species, when present, are usually attended by ants. The presence of ants around the base of the plants is usually a good clue to the presence of these aphids.

DAMAGE

These aphids occur infrequently and only occasionally cause injury. High populations may stunt growth, but more serious is that the tops may be weakened by their feeding and break off during harvest, leaving the carrot in the ground.

MANAGEMENT

Biological Control

Because of their location near and below the soil line, predators and parasites have a difficult time finding these aphids. Ants that tend aphids also discourage the activity of predators and parasites.

Cultural Control

Sanitation and crop rotation to nonhost crops is important in reducing the buildup of these aphids and their injury.

Organically Acceptable Methods

Cultural controls are acceptable for use on organically grown produce.

Monitoring and Treatment Decisions

No treatment thresholds have been established for these aphids.

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. Use allowed under a supplemental label.
 
B. CYFLUTHRIN*
  (Baythroid XL) 1.6–2.8 oz 12 0
  MODE-OF-ACTION GROUP NUMBER1: 3
  COMMENTS: Ground application with 30 gallons per acre preferred but 10 gal water/acre by air is acceptable. Use a silicone surfactant.
 
C. MALATHION
  (Malathion 8 Aquamul) 1–1.5 pt 12 7
  MODE-OF-ACTION GROUP NUMBER1: 1B

** 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 1B Group 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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