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ARS Home » Pacific West Area » Corvallis, Oregon » Horticultural Crops Research » Research » Publications at this Location » Publication #292460

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

Location: Horticultural Crops Research

Title: Exploring the characteristics of Pythium communities: Can knowledge about pathogen communities improve disease control?

item Weiland, Jerry
item GARRIDO, PATRICIA - Oklahoma State University
item Grunwald, Niklaus - Nik
item GARZON, CARLA - Oklahoma State University

Submitted to: Phytopathology
Publication Type: Abstract Only
Publication Acceptance Date: 3/28/2013
Publication Date: 11/1/2013
Citation: Weiland, G.E., Garrido, P., Grunwald, N.J., Garzon, C. 2013. Exploring the characteristics of Pythium communities: Can knowledge about pathogen communities improve disease control?. In: Phytopathology. Annual Meeting of the American Phytopathological Society, August 10-14, 2013, Austin, Texas.

Interpretive Summary:

Technical Abstract: Pythium species are an important component of the soilborne pathogen complex, causing damping-off of tree seedlings in forest nurseries. However, little is known about the phenotypic or genotypic diversity of forest nursery Pythium communities because disease control relies almost exclusively on chemical fumigants with broad spectrum efficacy. As fumigant use declines worldwide, knowledge about these communities will be necessary to develop new and more selective disease control measures. To this end, we are characterizing Pythium communities at three forest nurseries. To date, 19 Pythium species have been identified and population analyses indicate different degrees of genetic diversity for three commonly isolated species, P. irregulare, P. sylvaticum, and P. ultimum. In greenhouse trials with inoculated Douglas-fir seedlings, eight species each were categorized as either highly virulent or weakly virulent. In paired-culture assays, variation was observed among Pythium species and isolates in suppression by Streptomyces lydicus, a biocontrol agent. The variability found within these Pythium communities exemplifies the difficulty encountered in trying to find a single disease control measure to replace fumigation. An integrated pest management approach involving coordinated measures, each of which target a different component of a given pathogen complex, may be necessary to manage diseases caused by multiple pathogen species.