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UC Pest Management Guidelines


Adult European fruit lecanium, Parthenolecanium corni.

Apricot

European Fruit Lecanium

Scientific name: Parthenolecanium corni

(Reviewed 11/07, updated 11/07)

In this Guideline:


DESCRIPTION OF THE PEST

The European fruit lecanium, also known as the brown apricot scale, occurs throughout California but is rarely a problem. This scale has one generation per year. It overwinters as a nymph on twigs and small branches. In spring, it grows rapidly and secretes large amounts of honeydew. The adult cover is domed, shiny brown, and about 0.25 inch in diameter with several ridges along the back. The females are parthenogenic (do not mate) and lay many eggs, filling the entire space beneath the covers. They die after egg production.

DAMAGE

The European fruit lecanium sucks juices from leaves and twigs. Low to moderate populations apparently are not damaging, but abundant populations reduce terminal growth and vigor. The chief injury is caused by the production of large amounts of honeydew; sooty mold growing on the honeydew can blacken areas on leaves and fruit.

MANAGEMENT

Biological control is frequently effective; if treatment is needed, oil applied during dormancy or delayed dormancy is the most effective way to reduce populations of this pest and the least disruptive to biological control. Crawlers will die in hot weather (over 100°F).

Biological Control
Parasitic wasps play an important role in controlling this scale. The most important of these parasites are Coccophagus, Encyrtus, and Metaphycus spp. Parasitized nymphs are almost black and have convex covers; unparasitized nymphs are flat. Several parasites commonly emerge from a single parasitized adult scale, leaving a perforated cover. If parasite activity is hindered by ants tending and protecting the scales, take measures to control ants.

Organically Acceptable Methods
Biological control and certain oil sprays are acceptable for use on organically grown apricots.

Monitoring and Treatment Decisions
Apply treatments during the dormant or delayed dormant period before rapid scale growth begins in early spring. High populations of soft scales often result from the use of chemicals that are disruptive to parasites and predators. If a high degree of parasitization is observed, treatments may be delayed until late spring after crawlers emerge. Treat during the dormant or delayed dormant period if, during the previous year, scale populations or sooty mold were observed.

Take a fruit damage sample at harvest to assess the effectiveness of the current year's IPM program and to determine the needs of next year's program (see FRUIT SAMPLING AT HARVEST). Record results (sample form)—(115 KB, PDF).

Common name Amount to Use** R.E.I.+ P.H.I.+
(trade name) (conc.) (dilute) (hours) (days)

  Calculate impact of pesticide on air quality
When choosing a pesticide, consider information relating to the impact on natural enemies and honey bees and environmental impact. Not all registered pesticides are listed. Always read label of product being used.
 
A. DORMANT OIL such as:
  DORMANT FLOWABLE EMULSION 6 gal 1–1.5 gal 4 0
  NARROW RANGE OIL# 4 gal 1.5 gal 4 0
  MODE OF ACTION: Contact including smothering and barrier effects.
  COMMENTS: Oil alone will control light to moderate populations. Some of the new lower-chilling varieties, especially Poppycot, can be highly susceptible to oil damage. Use extreme care when applying oil to these varieties. Check with certifier to determine which products are organically acceptable.
 
 
**  For concentrate applications, use the amount given in 80-100 gal water/acre or lower if the label allows; for dilute application, amount is per 100 gal water to be applied in 300-400 gal water/acre, according to label.
+ 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.
# Acceptable for use on organically grown produce.

IMPORTANT LINKS

[Precautions]

PUBLICATION

[UC Peer Reviewed]

UC IPM Pest Management Guidelines: Apricot
UC ANR Publication 3433
Insects and Mites
W. W. Coates, UC Cooperative Extension, San Benito County
R. A. Van Steenwyk, Insect Biology, UC Berkeley
W. J. Bentley, UC IPM Program, Kearney Agricultural Center, Parlier
K. R. Day, UC Cooperative Extension, Tulare County
K. A. Kelley, UC Cooperative Extension, Stanislaus County
J. L. Caprile, UC Cooperative Extension, Contra Costa County
Acknowledgment for contributions to Insects and Mites:
L. C. Hendricks, UC Cooperative Extension, Merced County

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