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UC Pest Management Guidelines


Crop damaged by Italian pear scale.

Plum

Italian Pear Scale

Scientific name: Epidiaspis leperii

(Reviewed 5/06, 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 plum trees; it is usually not a problem.

DAMAGE

This scale inflicts its sucking damage on the wood of the tree resulting in reduced tree vigor.

MANAGEMENT

Light populations of Italian pear scale do not harm trees; damaging infestations are rare in California.

Organically Acceptable Methods
Bordeaux treatments, oil sprays, or oil and lime sprays used during the dormant season on organically certified produce.

Treatment Decisions
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 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#
  MODE OF ACTION GROUP NAME (NUMBER1): Multi-site contact (M1)
  COMMENTS: These materials control the growth of lichens, which provide protection to the scale. The removal of the lichens 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 making Bordeaux mixtures, 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 GROUP NAME (NUMBER1): A contact fungicide with 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 dieback, 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. Some varieties, especially those that are weak growers or low in vigor because of soil or other location-related issues, can be especially sensitive to oil. Not all oil products 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.
# Acceptable for use on organically grown produce.
1 Group numbers are assigned by the Fungicide Resistance Action Committee (FRAC) according to different modes of actions (for more information, see http://www.frac.info/). Fungicides with a different group number are suitable to alternate in a resistance management program. In California, make no more than one application of fungicides with mode of action Group numbers 1,4,9,11, or 17 before rotating to a fungicide with a different mode of action Group number; for fungicides with other Group numbers, make no more than two consecutive applications before rotating to fungicide with a different mode of action Group number.

[Precautions]

PUBLICATION

[UC Peer Reviewed]

UC IPM Pest Management Guidelines: Plum
UC ANR Publication 3462
Insects and Mites
W. J. Bentley, UC IPM Program, Kearney Agricultural Center, Parlier
K. R. Day, UC Cooperative Extension, Tulare County
Acknowledgment for contributions to Insects and Mites:
R. E. Rice, Kearney Agricultural Center, Parlier

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