Apple rust mite

Apple rust mites are too small to see without magnification, but their feeding produces a characteristic bronze or russeted discoloration on apple leaves and fruit skin. You will notice the damage first as a subtle dulling of leaf surfaces in early summer, progressing to a leathery brown texture by midsummer. These eriophyid mites overwinter under bud scales and emerge with new growth across Western Washington orchards.

Predatory mites, particularly Typhlodromus species, provide excellent biological control when conserved. Avoid carbaryl and other broad-spectrum insecticides that destroy these natural enemies. Dormant oil in late winter reduces overwintering populations. Sulfur sprays during the growing season offer targeted control if predator populations are insufficient.