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UC Pest Management Guidelines

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Almond

European Fruit Lecanium

Scientific name: Parthenolecanium corni

(Reviewed 1/05, updated 1/05)

In this Guideline:

Description of the pest
Damage
Management

DESCRIPTION OF THE PEST

European fruit lecanium, also known as the brown apricot scale, occurs throughout the Central Valley and is becoming an increasing problem as growers reduce dormant sprays. The adult female's domed shell is shiny brown, about 0.4 inch in diameter. Eggs are laid in spring and hatch from May to July. The young develop through the remainder of the season and overwinter on twigs and small branches as partly grown crawlers. There is one generation each year.

DAMAGE

The chief injury is the production of honeydew that, in large amounts, can damage leaves and fruit. Sooty mold growing in the honeydew can cause blackened areas on leaves and fruit.

MANAGEMENT

Natural enemies frequently keep lecanium scale below damaging populations. If treatment is needed, oil during dormancy or delayed dormancy is the best treatment. Use dormant spur sampling to determine need for treatment.

Biological Control

Many natural enemies help to control populations of European fruit lecanium. Common predators include lady beetles (Chilocorus orbus, Hyperaspis spp., Rhyzobius lophanthae,) lacewings, the predaceous sap beetle (Cybocephalus californicus), and predatory seed bugs (Phytocoris spp.). Parasites include Aphytis spp., Coccophagus spp., Encarsia spp., and Metaphycus spp. Frequently, scales found during the growing season are heavily parasitized.

Organically Acceptable Methods

Naturally occurring biological control and oil sprays are organically acceptable methods.

Monitoring and Treatment Decisions

To determine if a dormant treatment is warranted, follow the sampling and treatment threshold guidelines in the section DORMANT SPUR SAMPLING. Examine scales during summer for parasitism before deciding to spray; if parasites are not present and treatment is necessary, a summer oil spray can be applied. When treatment is necessary, however, it is best to treat when leaves are off during the dormant or delayed dormant period. Oil alone is usually all that is required to manage this pest in the dormant season within an IPM program; the addition of another insecticide is necessary only when infestations are severe.

Common name		Amount to use**		P.H.I.+
(trade name)		(conc.)	(dilute)	(days)

	DORMANT OR DELAYED DORMANT
A.	DORMANT OIL such as:
	DORMANT FLOWABLE EMULSION#	6 gal	1-1.5 gal
	NARROW RANGE OIL#	4 gal	1.5 gal
	COMMENTS: Oil is an option if Bacillus thuringiensis is to be used at bloom for control of caterpillars.

B.	DORMANT OIL such as:
	DORMANT FLOWABLE EMULSION	6 gal	1-1.5 gal
	NARROW RANGE OIL	4 gal	1.5 gal
	...PLUS...
	DIAZINON*50WP	3 lb	1 lb
	4EC	3 pt	1 pt
	COMMENTS: Avoid drift or runoff into surface waters or choose alternative materials. Diazinon has been found in surface waters at levels that violated federal and state water quality standards.
	...OR...
	CHLORPYRIFOS*
	(Lorsban) 4EC	2 pt	0.5 pt
	COMMENTS: Apply chlorpyrifos only during dormant or delayed dormant period and do not allow meat or dairy animals to graze in treated orchards. Avoid drift or runoff into surface waters or choose alternative materials. Chlorpyrifos has been found in surface waters at levels that violated federal and state water quality standards.

	SPRING OR SUMMER
A.	NARROW RANGE OIL#
	(Omni Supreme and others)	2-4%	0.25-1%	when dry
	COMMENTS: Monitor before treating to determine if parasites are present. If scale are parasitized, a treatment may not be necessary. Be sure that trees are well-watered to avoid phytotoxicity. Works by contact activity only so good coverage is essential.

**	For dilute applications, rate is per 100 gal water to be applied in 300-500 gal water/acre, according to label; for concentrate applications, use 80-100 gal water/acre, or lower if the label allows.
+	Preharvest interval. Do not apply within this many days of harvest.
*	Permit required from county agricultural commissioner for purchase or use.
#	Acceptable for use on organically grown produce.

PUBLICATION

UC IPM Pest Management Guidelines: Almond
UC ANR Publication 3431
Insects and Mites
F. G. Zalom, Entomology, UC Davis
C. Pickel, UC IPM Program, UC Cooperative Extension, Sutter/Yuba counties
W. J. Bentley, UC IPM Program, Kearney Agricultural Center, Parlier
R. L. Coviello, UC Cooperative Extension, Fresno Co
R. A. Van Steenwyk, Insect Biology, UC Berkeley
M. W. Freeman, UC Cooperative Extension, Fresno Co.
Acknowledgment for contributions to the insects and mites section:
R. E. Rice, Kearney Agricultural Center, Parlier
L. C. Hendricks, UC Cooperative Extension, Merced Co.

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