Problem: Mites (Plum)
Several species of mites attack plums, including the twospotted spider mite (Tetranychus urticae) and the plum rust mite (Aculus fockeui). Twospotted spider mites, which cause leaf stippling and webbing, may be detected on white paper. Plum rust mites, which cause leaf silvering and curling and fruit russeting, are microscopic and cannot be seen without the aid of a microscope or strong hand lens. These pests, related to spiders, cause damage by sucking sap from the fruit surface and the undersides of leaves. As a result of their feeding, the tree''s green leaf pigment disappears, producing the stippled or silvered appearance. Mites are active throughout the growing season but are favored by hot, dry weather (70°F and up). By midsummer, they have built up to tremendous numbers.
Apply an insecticide labeled for this pest, following label directions.