Pear rust mite
Epitrimerus pyri (Nalepa)
The overwintering stage is a light brown, wedge-shaped adult, which cannot be seen without a 15X hand lens (A). The summer forms are nearly white in color, and even smaller than the overwintered adults.
Most fruit-growing states and provinces in eastern North America.
Attacks pear, feeding on the first green tissue at the bud base, later moving to the foliage or fruit. Feeding causes leaves to turn brown or bronze (B), which may stunt the growth of young trees; on older trees, the damage to fruit is far more significant. Severe russetting of the fruit can leave the entire surface rough and brown (C), which alters or destroys the desirable varietal skin appearance. Early in the growing season, mite feeding at the calyx or stem ends gives a localized russetting to those areas. If mite growth is unchecked, this feeding and russetting may spread over the fruit entirely.
Outbreaks may be worse in areas receiving extensive sprays of materials destructive to predators, and the development of miticide-resistant strains are suspected in some cases. A preventive petal fall spray of a contact miticide is probably most advisable in blocks with a history of rust mite infestations.
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