Pearleaf blister mite
Editor’s note: This article is from the archives of the MSU Crop Advisory Team
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Bob Bricault, an MSU Horticulture educator in Washtenaw County, received several samples of ornamental pear leaves last week that were covered with brown spots on the undersides and blistered on the tops. Bob diagnosed the problem as pearleaf blister mite, a microscopic mite that causes these symptoms. Most of the time the injury is minor and nothing to worry about, but occasionally nearly every leaf turns brown. The only published control strategies for this mite is to plant resistant cultivars of ornamental pear, or to spray with infested trees with a horticultural oil in April before the buds begin to swell.