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Disease Note

First Report of Chestnut Blight in Minnesota. D. W. French, Department of Plant Pathology, University of Minnesota, St. Paul 55108. W. L. MacDonald, Department of Plant Pathology, West Virginia University, Morgantown 26505; E. Hayes, Minnesota Department of Natural Resources, Rochester 55904; and M. L. Double, Department of Plant Pathology, West Virginia University. Plant Dis. 69:905. Accepted for publication 20 May 1985. Copyright 1985 The American Phytopathological Society. DOI: 10.1094/PD-69-905c.

Endothia parasitica (Murr.) P. J. & H. W. And., the causal agent of chestnut blight, was found in southeastern Minnesota (Olmsted County) infecting a stand of 22 American chestnuts (Castanea dentata (Marsh.) Borkh.). This is the first report of E. parasitica in Minnesota. These trees were established about 1880 and range in size from 18.0 to 56.6 cm, 1.4 m above the ground. All trees are infected and eight have died. The disease was not observed in a 1976 survey but has been active in this stand for the last few years. Other American chestnuts within 16 km of this stand appear to be disease-free. The identity of the fungus was confirmed when perithecia were found in pairings with two mating types from West Virginia. In tests of vegetative compatibility, the Minnesota isolate was incompatible with 37 vegetative compatibility groups.