Ornamental Plum: Scales

• Categories: Ornamental Plum Ornamental Plum Insects Ornamental trees Ornamentals
• Last review date: 2026-08-29 08:19

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

See "Using Integrated Pest Management (IPM) in the Landscape" for successful problem management techniques.

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

• 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

If you choose to use a pesticide, some examples of products that are legal in Washington are listed below. Some products are labeled for just INDOOR or just OUTDOOR use, or may allow both uses. Be sure to choose a product appropriate for your situation. Always read and follow all label directions.

• Hi-Yield Dormant Spray
  Active ingredient: Paraffinc oil
  EPA registration number: 7401-428
• R-T-U Year-Round Spray Oil
  Active ingredient: mineral oil
  EPA registration number: 6218-78
• Safer Brand Insect Killing Soap Concentrate II [Organic]
  Active ingredient: potassium salts of fatty acid
  EPA registration number: 42697-60
• Azera Gardening [Organic]
  Active ingredient: azadirachtin, pyrethrins
  EPA registration number: 1021-1872
• This list may not include all products registered for this use.