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UC Pest Management Guidelines


Artichoke aphids, Capitophorus elaeagni

Artichoke

Artichoke Aphid

Scientific name: Capitophorous elaeagni

(Reviewed 1/07, updated 6/09)

In this Guideline:


DESCRIPTION OF THE PEST

Artichoke aphids are pale greenish white to yellowish green, almost translucent aphids with pale appendages. The tips of the very long cornicles (siphunculi) are distinctly dusky in color. The tubercles (located at the base of the antennae) are diverging in contrast to those in the green peach aphid, which are converging. Wingless adults have a long capitate hair on the third and the posterior abdominal segments; winged adults have an almost rectangular solid black spot on their abdomen. This aphid overwinters on its primary hosts, Elaeagnus species (Russian olive, silverberry, and others), migrating in summer to thistles (Circium, Carduus) and to artichokes where it can cause economic damage.

DAMAGE

Large numbers of these aphids cause artichoke leaves to curl and turn yellow and the plants to show retarded growth, resulting in the formation of undersize or deformed artichoke buds. In addition, bud stalks weaken and can no longer support the weight of developing buds, causing them to droop. Also, buds that are close to harvest get contaminated with aphid bodies. Besides this direct-feeding damage, artichoke aphid characteristically secretes copious amount of honeydew, which is deposited onto leaves and developing artichoke buds in the lower canopy, giving them a wet and shiny appearance. Honeydew deposits on the foliage result in the growth of sooty mold, which covers the leaf surface and interferes with photosynthesis. It is estimated that 10-15% of the crop harvested during August-September is lost because of poor quality that is a result of aphid damage. Also, aphid injury may delay the fall harvest by several weeks because of retarded plant growth.

MANAGEMENT

Artichoke aphid is a serious problem on perennial artichokes during summer when the average humidity and air temperature are in the high range; it is not a problem in southern California annual artichoke fields. When choosing insecticide treatments to control other pests, consider the impact of the materials on natural enemies of this aphid. When conditions are ideal for development of populations, monitor the crop weekly to determine the need to treat.

Biological Control
Several parasitic wasps attack aphids in artichoke, most notably species in the genera Diaeretiella and Lysiphlebus. General predators including lady beetles, syrphid fly, and lacewings also consume aphids. In addition, a portion of the population may be killed by a fungal disease caused by Entomophthora aphidis. However, naturally occurring predators, parasites, and pathogenic fungi rarely provide timely control because of considerable time lag between the buildup of the parasite/predator populations and the aphid populations. Preserve populations of beneficial insects by avoiding unnecessary insecticide applications and by providing acceptable habitat for these predators and parasites.

Cultural Control
Destroy crop residue immediately after harvest.

Organically Acceptable Methods
Biological controls, cultural controls, and neem oil are acceptable for use on organically certified crops.

Monitoring and Management Decisions
An outbreak of artichoke aphids is most likely to occur during periods of high average daily temperatures coupled with high relative humidity (98–100%). These conditions generally prevail from June to September. Intensify field monitoring during this period by making weekly observations.This aphid remains on the underside of the older leaves when population levels are low; at higher population levels, aphids spread rapidly throughout the plant. A population density of an average of 3 aphids per leaflet is considered a treatment threshold. At this population level, isolated plants will start to show the sooty mold on the foliage. Within a few days, the infestation becomes more conspicuous as large contiguous areas start turning black from the growth of sooty mold.

Common name Amount/Acre R.E.I.+ P.H.I.+
(trade name)   (hours) (days)

  Calculate impact of pesticide on air quality
When choosing a pesticide, consider information relating to impact on natural enemies and honey bees and to the environment. Not all registered pesticides are listed. Always read label of product being used.
 
A. IMIDACLOPRID
  (Provado) 1.6F 4–10 oz 12 7
  MODE OF ACTION GROUP NUMBER1: 4A
  COMMENTS: Do not apply more than 40 oz/acre/crop season. Do not apply this product or allow it to drift to blooming crops or weeds if bees are visiting the treatment area.
 
B. BIFENTHRIN*
  (Brigade) WSB 16 oz 12 5
  (Brigade) 2 EC 6.4 fl oz 12 5
  MODE OF ACTION GROUP NUMBER1: 3
  COMMENTS: Do not exceed 16 oz/acre between bud formation and harvest. Do not exceed 80 oz/acre/season. Mixing bifenthrin and permethrin at their half rate gives acceptable control at less cost; however, be sure to observe all restrictions and precautions on the labels of both products.
 
C. PYRETHRIN/ROTENONE
  (Pyrellin EC) Label rates 12 0.5
  MODE OF ACTION GROUP NUMBER1: 3/21
 
D. NEEM OIL#
  (Trilogy) 1% solution 4 0
  MODE OF ACTION: Unknown. A botanical insecticide.
  COMMENTS: Thorough coverage is important; apply in a minimum of 75 gal water/acre.
 
+ 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.
* Permit required from county agricultural commissioner for purchase or use.
# Acceptable for use on organically grown produce.
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 Group numbers are assigned by IRAC (Insecticide Resistance Action Committee). For additional information, see their Web site at http://www.irac-online.org/.

[Precautions]

PUBLICATION

[UC Peer Reviewed]

UC IPM Pest Management Guidelines: Artichoke
UC ANR Publication 3434
Arthropods
M. A. Bari, Artichoke Research Foundation, Salinas
E. T. Natwick, UC Cooperative Extension, Imperial County
Acknowledgment for contributions to Arthropods:
W. E. Chaney, UC Cooperative Extension, Monterey County
W. L. Schrader, UC Cooperative Extension, San Diego County
L. Handel and T. K. Shannon, Kleen Globe, Inc., Castroville, CA

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