WSU Extension

Hortsense

Dogwood
 
Disease
Anthracnose 
Armillaria root rot 
Collar rot 
Leaf scorch and leaf roll 
Powdery mildew 
Insect
Brown soft scale 
Lecanium scale 
Oystershell scale 



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Caption: Lecanium scales
Photo by: R.S. Byther
  
Dogwood : Lecanium scale
(revision date: 3/22/2021)


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

Biology
Lecanium scales are rounded brown (or mottled) insects. Adults are from 1/8" to 1/4" in diameter. Lecanium scales produce large amounts of sticky honeydew, which may have sooty mold growing on it. They overwinter on the bark, but the crawlers feed on the underside of leaves from May to August (approximately). Scales may be spread from infested plants by people, other insects, wind, and birds.
Management Options


Non-Chemical Management
  • Natural predators such as ladybird beetles and green lacewings may greatly reduce the number of crawlers.
  • If the infestation is minor, scales may be wiped from the bark or leaves.
  • Prune and destroy heavily infested branches.
Select non-chemical management options as your first choice!

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

Scout for crawlers. Insecticide applications can be effective when applied to control the immature crawlers stage, usually in late spring to early summer. Oils are effective in the delayed dormant period. Use superior type oil sprays only on overwintering nymphs. 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.

Listed below are examples of pesticides that are legal in Washington. Always read and follow all label directions.
  • All Seasons Horticultural & Dormant Spray Oil Conc [Organic]
    Active ingredient: oil/pet distillate  |  EPA reg no: 4-80
  • Hi-Yield Dormant Spray
    Active ingredient: oil/pet distillate  |  EPA reg no: 7401-428
  • Safer Brand BioNEEM Multi-Purpose Insecticide & Repellent Conc [Organic]
    Active ingredient: azadirachtin  |  EPA reg no: 70051-6-42697
  • Safer Brand Insect Killing Soap Conc II [Organic]
    Active ingredient: potassium salts of fatty acid  |  EPA reg no: 42697-60
  • This list may not include all products registered for this use.
Images

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Caption: Lecanium scales
Photo by: R.S. Byther