Walnut: European fruit lecanium
categories: Tree Fruits Walnut Walnut Insects
revision date: 2023-04-04 12:00
Photo by: R.S. Byther
Biology
The European fruit lecanium is a shiny brown scale insect found on twigs. Adults are 1⁄8″ to 1⁄4″ in diameter and roughly turtle-shaped. They may have light markings or appear somewhat waxy. Crawlers (immature scales) are flatter and may be found on leaves. Scales produce large amounts of honeydew, a sweet, sticky material which may attract ants or become covered with a growth of dark sooty mold. Heavily infested branches may be wilted, yellowish, or show other signs of stress. New growth may be stunted or lacking. This lecanium scale closely resembles frosted scale, but does not produce the waxy coating found on frosted scale in the spring. Lecanium scales are common pests in the landscape, infesting many plants including maple, rhododendron, and fruit trees.
Management Options
Use Integrated Pest Management (IPM) for successful plant problem management.
Non-chemical Management
Select non-chemical management options as your first choice!
- Natural enemies such as ladybird beetles, green lacewings, and parasitic wasps help control scale populations. Avoid use of broad-spectrum insecticides which kill these and other beneficial insects.
- Control honeydew-feeding ants which may protect scales from predators.
- Hand-wipe to help control minor infestations.
- Prune and destroy heavily infested branches, when practical.
Chemical Management
IMPORTANT: Visit Home and Garden Fact Sheets for more information on using pesticides.
- Apply oil during delayed-dormant period (when buds start to swell) to control 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.