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Disease Note

Discula Species Associated with Anthracnose of Dogwood in the Pacific Northwest. D. S. Salogga, Center for Urban Horticulture, University of Washington, Seattle 98195. J. F. Ammirati, Department of Botany, University of Washington, Seattle 98195. Plant Dis. 67:1290. Accepted for publication 19 August 1983. Copyright 1983 American Phytopathological Society. DOI: 10.1094/PD-67-1290.

Since about 1976, Cornus nuttallii Aud. in the Puget Sound Basin area has shown severe symptoms of anthracnose, including twig and stem dieback. Small necrotic areas on newly expanded leaves in early spring typically develop into large, irregular brown regions along veins and occasionally on petioles. A species of Discula Sacc., perhaps new to science, has been isolated repeatedly from these necrotic regions. Dead 1-yr-old twigs are common on trees with foliar symptoms, and entire branches may have dead immature and expanded leaves. After 23 yr of infection, only the ends of the branches may have foliage, and the lower part of the canopy may consist of dead branches. The disease also occurs in Idaho, Oregon, and British Columbia (to a lesser extent on C. florida L. and C. kousa Hance) and has been reported from Washington; a similar anthracnose was reported this year from the Northeast.