How to Manage Pests
UC Pest Management Guidelines
Scientific name: Parthenolecanium
In this Guideline:
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
filling the entire space beneath the covers. They die after egg production.
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.
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).
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)— .
||Amount to Use**
|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.
||DORMANT OIL such as:
||DORMANT FLOWABLE EMULSION
||NARROW RANGE OIL#
||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.
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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