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UC Pest Management Guidelines


Crop damaged by Italian pear scale.

Prune

Italian Pear Scale

Scientific name: Epidiaspis leperii

(Reviewed 6/06, updated 4/09)

In this Guideline:


DESCRIPTION OF THE PEST

Italian pear scale covering is circular, shiny light gray, and has a brown exuvia slightly off center. The body under the scale covering is dark reddish purple. The scale is often found under moss and lichen on old prune trees.

DAMAGE

This scale inflicts its sucking damage on the wood of the tree. Heavy populations can cause bark cracking and reduced tree vigor; however it is usually not a problem.

MANAGEMENT

Light populations of Italian pear scale do not harm trees; damaging infestations are unusual in California. Insecticide and oil sprays often have little effect on this scale because a large number of them overwinter in the adult stage and are concealed in the tree's moss and lichens. If treatment is necessary, treat during the dormant and delayed dormant period for most effective control. Registered copper and lime sulfur sprays directed at moss and lichens on the tree bark will aid in control of this scale.

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

  Calculate impact of pesticide on air quality
The following materials are listed in order of usefulness in an IPM program, taking into account efficacy, impact on natural enemies and honey bees, and impact of the timing on beneficials. When choosing a pesticide, also consider information relating to environmental impact. Not all registered pesticides are listed. Always read label of product being used.
 
A. BORDEAUX#
  10-10-100 or Label rates 24
  FIXED COPPER#
  COMMENTS: These treatments are to control the growth of lichens, which provide protection to the scale. Their removal will aid in the control of the scale. This is a slow procedure requiring 1 or more years to be effective. Although the lichens are killed quickly, considerable weathering must occur before they are removed. Thorough coverage including trunks and limbs is essential. Not all copper compounds are approved for use in organic production; be sure to check individual products. For information on creating a Bordeaux mixture, see UC IPM Pest Note: Bordeaux Mixture, ANR Publication 7481.
 
B. DORMANT OIL such as:
  DORMANT FLOWABLE EMULSION 6 gal 1.5 gal 4
  NARROW RANGE OIL# 4 gal 1 gal 4
  MODE OF ACTION: Contact including smothering and barrier effects.
  COMMENTS: Oil used alone will only provide partial control. Oil applications at this time may cause some young shoots to burn or die back, especially in years when trees are water-stressed, or have recently been subjected to freezing temperatures or to dry winds. Dormant flowable emulsion is less likely to cause burn. The Moyer variety is highly susceptible to oil injury; delaying the oil spray until late Feb.to March 1 will reduce oil burn. Not all oils are organically acceptable; be sure to check individual products.
 
** 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.
# 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: Prune
UC ANR Publication 3464
Insects and Mites
C. Pickel, UC IPM Program, Sutter/Yuba counties
F. J. A. Niederholzer, UC Cooperative Extension, Sutter/Yuba counties
W. H. Olson, UC Cooperative Extension, Butte County
F. G. Zalom, Entomology, UC Davis
R. P. Buchner, UC Cooperative Extension, Tehama County
W. H. Krueger, UC Cooperative Extension, Glenn County
Acknowledgment for contributions to Insects and Mites:
W. O. Reil, UC Cooperative Extension Solano/Yolo counties

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