Understanding the Pathology of Douglas-fir Seedlings in Pacific Northwest Nurseries
Douglas-fir seedlings are infected by a number of Pythium species causing damping-off and root rot. As soil fumigation continues to be more tightly regulated, knowledge about the identity and pathogenicity of Pythium species in forest nurseries will be increasingly important for studies that evaluate the effectiveness of nonfumigant disease control measures, including fungicide and biological control efficacy trials. The diversity of Pythium species at three Pacific Northwest (PNW) forest nurseries was evaluated and each nursery was found to have a unique assemblage of species. Furthermore, each Pythium species was found to cause a different level of disease on Douglas-fir seedlings. Subsequent fungicide and biological control efficacy studies found that differences in species responses to mefenoxam, fosetyl-Al, and Streptomyces lydicus, a biological control agent.
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Author(s): Jerry Weiland
Publication: National Nursery Proceedings - 2013
Event:
Western Forestry and Conservation Nursery Association Meeting
2013 - Olympia, Washington