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Ornamental Plum: Scales

categories: Ornamental Plum Ornamental Plum Insects Ornamental trees Ornamentals

revision date: 2023-04-04 12:00

Yellow pencil pointing to Lecanium cales on twig shown on a black background.
Lecanium scales on twig
Photo by: R.S. Byther

Biology

Various species of scales attack ornamental plum trees. Depending on species, scales may be found on the upper or lower surfaces of leaves, or on twigs and branches. Symptoms of scale infestations may include yellowing and/or wilting of leaves on affected plant parts as well as the presence of honeydew, a sweet, sticky material produced by some species of scales. The honeydew may become covered with a dark growth of sooty mold. Scale insects are typically yellowish to dark brown or gray in color and rounded or oval in shape. They are generally 1/8″ long or less.

Management Options

Use Integrated Pest Management (IPM) for successful plant problem management.

Non-chemical Management

Select non-chemical management options as your first choice!

  • Ladybird beetles and parasitic wasps help control scale populations.
  • Minor infestations may be picked off by hand.
  • If practical, prune and destroy heavily infested branches.

Chemical Management

IMPORTANT: Visit Home and Garden Fact Sheets for more information on using pesticides.

  • Apply a delayed dormant oil just as buds begin to swell to control scale crawlers.
  • Homeowners should not make foliar applications to trees over 10 ft tall.
  • Consult a commercial pesticide applicator for treatment of trees and shrubs over 10 ft. tall.

Approved Pesticides

Listed below are examples of pesticides that are legal in Washington. Always read and follow all label directions.

  • Hi-Yield Dormant Spray
    Active ingredient: oil/pet distillate [EPA registration number: 7401-428]
  • R-T-U Year-Round Spray Oil
    Active ingredient: oil/pet distillate [EPA registration number: 6218-78]
  • Safer Brand BioNEEM Multi-Purpose Insecticide and Repellent Concentrate [Organic]
    Active ingredient: azadirachtin [EPA registration number: 70051-6-42697]
  • Safer Brand Insect Killing Soap Concentrate II [Organic]
    Active ingredient: potassium salts of fatty acid [EPA registration number: 42697-60]
  • This list may not include all products registered for this use.

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