Pearleaf blister mite
Eriophyes pyri (Pagenstecher)
The adults are very small and cannot be seen without a 15X hand lens; the body is white and elongate oval in shape, like a tiny sausage (A).
Most fruit-growing states and provinces in eastern North America.
Attacks pear. During winter, the feeding of the mites under the bud scales is believed to cause the bud to dry and fail to develop. This type of damage is similar to and may be confused with bud injury from insufficient winter chilling. Fruit damage occurs as a result of mites feeding on the developing pears, from the green tip stage through bloom, causing russet spots. These spots, which are often oval in shape, are usually depressed, with a surrounding halo of clear tissue. They are 6–12 mm (1/4–1/2") in diameter and frequently run together. A third type of injury is the curling (B) or blistering of leaves (C); blisters are 3–6 mm (1/8–1/4") across and, if numerous, can blacken most of the leaf surface.
A post-harvest insecticide application may be elected in the fall, when there is no danger of frost for at least 24–48 hr after the spray. If needed, a spray of insecticide mixed with oil, in the spring, just before the green tissue begins to show, will improve control.
The MSU IPM Program maintains this site as an access point to pest management information at MSU. The IPM Program is administered within the Department of Entomology, fueled by research from the AgBioResearch, delivered to citizens through MSU Extension, and proud to be a part of Project GREEEN.