How to Manage Pests

UC Pest Management Guidelines

Almond

European Fruit Lecanium

Scientific name: Parthenolecanium corni

(Reviewed 3/09, updated 3/09)

In this Guideline:


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, and summer temperatures consistently over 100°F, 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 certain oil sprays are organically acceptable.

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 per acre** R.E.I.+ P.H.I.+
(example trade name) (conc.) (dilute)
(hours) (days)

  Calculate impact of pesticide on air quality
The following materials are listed in order of usefulness in an IPM program, taking into account efficacy and impact on natural enemies and honey bees. When choosing a pesticide, also consider information relating to environmental impact. Not all registered pesticides are listed. Always read the label of the product being used.
 
DORMANT OR DELAYED DORMANT
A. DORMANT OIL such as:
  DORMANT FLOWABLE EMULSION# 6 gal 1–1.5 gal 4 0
  NARROW RANGE OIL# 4 gal 1.5 gal See label 0
  MODE OF ACTION: Contact including smothering and barrier effects.
  COMMENTS: Oil is an option if Bacillus thuringiensis is to be used at bloom for control of caterpillars. Check with certifier to determine which products are organically acceptable.
 
B. DORMANT OIL such as:
  DORMANT FLOWABLE EMULSION 6 gal 1–1.5 gal 4 0
  NARROW RANGE OIL 4 gal 1.5 gal See label 0
  MODE OF ACTION: Contact including smothering and barrier effects.
  . . . PLUS . . .
  DIAZINON*50WP 3 lb 1 lb 24 0
  MODE OF ACTION GROUP NUMBER1: 1B
  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 4E) 2 pt 0.5 pt 4 days 0
  MODE OF ACTION GROUP NUMBER1: 1B
  COMMENTS: Apply chlorpyrifos only during dormant or delayed dormant period and do not allow meat or dairy animals to graze in treated orchards. Not labeled for use in the Sacramento Valley. Follow best management practices to prevent off-site movement of this material into waterways. Chlorpyrifos has been found in surface waters at levels that violate federal and state water quality standards. Avoid use where possible. For tank mixes, observe all directions for use on all labels, and employ the most restrictive limits and precautions. Never exceed the maximum a.i. on any label when tank mixing products that contain the same a.i.
 

SPRING OR SUMMER
A. NARROW RANGE OIL#
  (Omni Supreme and others) 2–4% 0.25–1% 4 when dry
  MODE OF ACTION: Contact including smothering and barrier effects.
  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. Check with certifier to determine which products are organically acceptable.
 
** 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.
+ 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 these two intervals is the minimum time that must elapse before harvest may occur.
* 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/.

IMPORTANT LINKS

[Precautions]

PUBLICATION

[UC Peer Reviewed]

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
D. R. Haviland, UC IPM Program, UC Cooperative Extension, Kern County
R. A. Van Steenwyk, Insect Biology, UC Berkeley
Acknowledgment for contributions to Insects and Mites:
R. E. Rice, Kearney Agricultural Center, Parlier
L. C. Hendricks, UC Cooperative Extension, Merced County
R. L. Coviello, UC Cooperative Extension, Fresno County
M. W. Freeman, UC Cooperative Extension, Fresno County

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