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ARS Home » Pacific West Area » Corvallis, Oregon » Horticultural Crops Research » Research » Publications at this Location » Publication #300930

Research Project: Improved Strategies for Management of Soilborne Diseases of Horticultural Crops

Location: Horticultural Crops Research

Title: Understanding the pathology of Douglas-fir seedlings in Pacific Northwest nurseries

Author
item Weiland, Jerry

Submitted to: National Nursery Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 1/15/2014
Publication Date: 1/22/2015
Citation: Weiland, G.E. 2015. Understanding the pathology of Douglas-fir seedlings in Pacific Northwest nurseries. In: Rocky Mountain Research Station Proceedings 72. Annual Meeting of Western Forest and Conservation Nursery Association, August 6-7, 2013, Olympia, Washington. p. 38-40.

Interpretive Summary: 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.

Technical Abstract: 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.