How to Manage Pests
UC Pest Management Guidelines
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.
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.
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.
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.
UC IPM Pest Management Guidelines:
E. T. Natwick, UC Cooperative
Extension, Imperial County