Brownish crusty bumps or clusters of yellowish, brown, reddish, gray, or white scaly bumps cover the trunk, branches, or the undersides of leaves. The bumps can be scraped or picked off. Leaves turn yellow and may drop, and twigs or branches may die back. A shiny, sticky substance often coats the leaves, and may be covered with a black sooty mold.
Apply an insecticide labeled for scales, following label directions.