Pearleaf blister mite

You will see reddish to yellowish-green blisters erupting from pear leaves in spring as buds swell and leaves unfurl. Blisters turn brown or black by late season as tissue dies. Heavily infested leaves drop prematurely, weakening trees. These microscopic mites overwinter under outer bud scales and begin feeding immediately as buds burst. Three host plants including pear are affected.

Plan management for the following season after observing current year damage. Dormant sprays in late fall and winter target overwintering mites beneath bud scales if prior damage was severe. Avoid broad-spectrum insecticides that kill phytoseiid predator mites that naturally control blister mites. Heavy rain and cold weather suppress populations. Most trees tolerate mild blister mite injury.