Severe Epidemic of 'Marssonina' Leaf Blight on Quaking Aspen in Northern Utah

摘要

The extent of Marssonina leaf blight (Marssonina populi) on quaking aspen (Populus tremuloides) was observed in northern Utah and adjacent States in 1981 and 1982. Area of the epidemic and symptoms of the disease are described. On 1,000 acres (405 ha) in northern Utah, infection levels were 6 percent slight, 12 percent light, 32 percent moderate, 16 percent moderately heavy, and 34 percent heavy.