Stump Farm

The leaf gall on Bitter Cherry (Prunus emarginata) is caused by eriophyid mites. They feed on the underside of expanding leaves and the eruption forms on the topside. The galls don’t seem to harm the tree or the leaf.

The photos show the galls in late spring and mid-summer. Easy to see where the name comes from. They are quit striking in the spring (left). They turn white and fuzzy as the summer goes on (right).