Abstract:
Winter grain mite, Penthaleus major (Duges), is a small, colorful, cool season
mite that damages grass and cereal crops throughout the Pacific Northwest as well as in most other temperate regions of the world. Hosts include most
cereals and grasses of economic importance. Winter grain mite has been a frequent fall and winter pest of wheat, grass seed crops, and pastures in central Oregon, the Columbia Basin, and the Grande Ronde Valley. In recent years, large populations have appeared, causing significant damage to orchard grass and timothy pastures from Madras through Bend and to winter wheat in the Mid-Columbia region. It emerged as an important pest in the Mid-Columbia area in 2008, perhaps due to mild late-winter weather.
