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On June 2, 1998 in Wainwright, 200 km south-east of Edmonton, samples were taken from a single elm tree showing typical Dutch elm disease (DED) symptoms. Lab analysis showed that the fungus Ophiostoma nova-ulmi Brasier was the cause of its demise.
The infected tree was removed and burned at the Wainwright dump on July 28, 1998. The tree was treated as having DED although the results were not final at that time. For the remainder of the 1998 season to 2001, addition pheromone traps were placed throughout the municipality, but no beetles were found. All the remaining elm trees in the municipality were surveyed for DED and no other samples tested positive for DED.
No other cases of DED have been found in Alberta.
Tewari, J.P., Feddes-Calpas, J., and Brezden, S. 2001. First report of the Dutch Elm Disease from Alberta, Canada. Can. J. Plant Pathol., 23: 185-186.
The Dutch elm disease (DED) has been a devastating disease of elms in Europe and North America. The disease is present in Saskatchewan, Canada, and in Montana, U.S.A., which are two contiguous regions of Alberta. The province of Alberta has so far been free of this disease. However, during a province-wide elm inventory survey carried out in 1998 by the Society to Prevent DED, an approximately 70-year-old American elm tree (Ulmus americana L.) in a home-backyard in Wainwright, Alberta, was noticed to have typical DED symptoms. Isolation of the causal agent on potato dextrose agar and its study, by light and scanning electron microscopy, identified the pathogen to be Ophiostoma novo-ulmi Brasier. The cultures had both Graphium and Sporothrix anamorphs present. Ophiostoma novo-ulmi is considered to be the most virulent among the DED fungi and is thought to be responsible for the second pandemic of this disease. Consistent with this attribute of the pathogen, the wilted canopy in the Wainwright tree increased from 35 to 75% in about 45 days. Only red elm weevils were found in the affected tree. In absence of the elm bark beetles, the mode of transmission of this pathogen in the affected tree is uncertain, although elm firewood is suspected.
For information about STOPDED or Dutch elm disease contact stopded@shaw.ca at STOPDED Hotline: 1-877-837-ELMS (3567) |
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