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Disease Note. Chondrostereum purpureum Associated with Decline of Betula papyrifera in Thunder Bay, Ontario. J. A. McLaughlin, School of Forestry, Lakehead University, Thunder Bay, Ontario, Canada P7B 5E1. E. C. Setliff, School of Forestry, Lakehead University, Thunder Bay, Ontario, Canada P7B 5E1. Plant Dis. 74:331. Accepted for publication 26 February 1990. Copyright 1990 The American Phytopathological Society. DOI: 10.1094/PD-74-0331E. Dieback and decline of white birch (Betula papyrifera Marsh.) of
all age classes are evident throughout Thunder Bay. In September
1986, the wound pathogen Chondroslereum purpureum (Pers.:Fr.)
Pouz. was observed fruiting on a declining young white birch. [n
late summer of 1988, two more trees were observed with C. purpureum
basidiocarps. Subsequently, a survey for this fungus was conducted
in the city to assess its association with trees showing symptoms of
decline. Discolored wood was extracted from areas near branch or
trunk wounds on 26 of 39 symptomatic trees. Fifteen of these trees
yielded cultures of C. purpureum. Also, basidiocarps of C. purpureum
were found on B. pendula Roth. Acer sacchorinum L., and a Malus
sp. with decline symptoms. The pattern of disease incidence on birch
was reminiscent of silver leaf disease reported in an orchard in
Wisconsin (1). C. purpureum has been previously noted as the most
common fungus found in brown-stained white birch wood and one
of the most common fungi found in association with trunk defects
and decay. These results raise the question of what role this fungus
plays in the complex and economically important phenomenon known
as birch decline. |