Eriophyes pyri Pagenstecher
Pear leaf blister mite is a problem only on apples and pears grown in the western states. The injury is worse on apples than on pears (see Pears, Pear Leaf Blister Mite Injury; see photo).
Ordinarily the pear leaf blister mite is controlled in properly sprayed orchards. Certain weather conditions favor increased mite populations, and periodically the pest causes some injury. In general, however, losses are of minor importance. The fruits are attacked while young. They may have blister-like lesions in early season. At harvest irregularly shaped russet spots similar to those found on pears may occur on apple fruits. The fruits may also be deformed, and cracks may develop in russeted areas.
For control consult the State agricultural extension service or experiment station.
Pear leaf blister mite injury, shown on pear