European Fruit Lecanium

European fruit lecanium scale appears as hemispherical, brown bumps on branches and twigs of fruit trees in Western Washington, becoming most visible in late summer and fall. You will see scale insects that resemble small domes, grouped along twigs. Heavy infestations cause yellowing of foliage and branch dieback. Honeydew secretion attracts wasps and promotes sooty mold.

Apply horticultural oil in late dormancy before bud break to coat overwintering scales. Prune heavily infested branches if populations are light. Conserve parasitoid wasps and lady beetles. Maintain tree health through proper watering.