How to Manage Pests

UC Pest Management Guidelines

DESCRIPTION OF THE PEST

A group of related species, or possibly biotypes, form the black bean aphid complex. These individuals are superficially identical. The black bean aphid is a dark green to black, soft-bodied insect with a dark-colored head, antennae, and cornicles. The legs are black at the base and tips.

Black bean aphids form dense colonies on the undersides of celery leaflets. Winged black bean aphids develop under specific conditions such as overcrowding and plant stress, and disperse to other plants or fields.

DAMAGE

Black bean aphid populations can build up in celery to densities of several thousand per plant. This pest can inflict three types of damage on the celery crop. First, it can stunt plant growth and reduce yields through removal of significant amounts of sap. Secondly, it can transmit virus diseases such as western celery mosaic, celery calico, cucumber mosaic, and celery yellow spot. And finally, it can contaminate celery produce, particularly fresh market celery, with aphid honeydew and debris; this contamination can lower the crop value. Feeding by black bean aphids may distort plant growth and development more than feeding by other aphid species.

MANAGEMENT

Biological Control
Several parasitic wasps provide natural control of aphids in celery, most notably species in the genera Diaeretiella and Lysiphlebus. In some cases, these parasites can eliminate high densities of aphids over a few weeks period. Predators such as lady beetles, syrphid flies and lacewing also attack aphids. Populations of aphid natural enemies should be preserved by avoiding unnecessary insecticide applications and by providing acceptable habitat for these beneficials.

Cultural Control
Destroy crop residue immediately after harvest. Avoid other aphid-favored crops, such as lettuce, in adjacent, upwind fields. Intensify field monitoring for aphids when adjacent fields with aphid-favored crops are harvested.

Organically Acceptable Methods
Biological controls, cultural controls, and insecticidal soaps are acceptable for use on organically grown produce.

Monitoring and Treatment Decisions
Economic thresholds for aphids on celery have not been established. Aphid survival and development are historically greatest during periods with temperatures that are less than 80°F. However, the black bean aphid is more tolerant of hot temperatures than other species, and therefore cause problems into summer. Generally, black bean aphids can be tolerated on young celery plants. On fresh market celery, infestations are more important when the petioles (stalks) start to form and when the rows begin to close. Infestations tend to be erratic in the field, so sample several locations. Sample intermediate-age stalks because this is where the highest population levels of aphids are found. Concentrate on field edges particularly where celery fields border harvested lettuce fields.

PUBLICATION

UC IPM Pest Management Guidelines: Celery
UC ANR Publication 3439
Insects
L. D. Godfrey, Entomology, UC Davis
J. T. Trumble, Entomology, UC Riverside
Acknowledgement for contributions to Insects:
W. E. Chaney, UC Cooperative Extension, Monterey County

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