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ARS Home » Pacific West Area » Corvallis, Oregon » Horticultural Crops Research Unit » Research » Publications at this Location » Publication #301327
Title: Phytophthora community structure analyses in Oregon nurseries inform systems approaches to disease management

Author
item PARKE, J - Oregon State University
item FIELAND, V - Oregon State University
item LEWIS, C - Oregon State University
item Knaus, Brian
item Grunwald, Niklaus - Nik

Submitted to: Phytopathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/1/2014
Publication Date: 10/1/2014
Citation: Parke, J.L., Fieland, V.J., Lewis, C., Knaus, B.J., Grunwald, N.J. 2014. Phytophthora community structure analyses in Oregon nurseries inform systems approaches to disease management. Phytopathology. 104(10):1052-1062.

Interpretive Summary: Nursery plants are important vectors for plant pathogens. Understanding what pathogens occur in nurseries in different production stages can be useful to development of integrated systems approaches for management of plant diseases. Four horticultural nurseries in Oregon were sampled every two months for four years to determine the identity and community structure of Phytophthora species associated with different sources and stages in the nursery production cycle. Pathogens in the genus Phytophthora cause diseases on many ornamentals and are of particular interest to nursery growers. This study provides quantitative data on incidence and diversity of Phytophthora pathogens observed. Nurseries differed in composition of Phytophthora communities across years, seasons, and source within the nursery. These findings suggest likely contamination hazards and target critical control points for management of Phytophthora disease using a systems approach.

Technical Abstract: Nursery plants are important vectors for plant pathogens. Understanding what pathogens occur in nurseries in different production stages can be useful to development of integrated systems approaches. Four horticultural nurseries in Oregon were sampled every two months for four years to determine the identity and community structure of Phytophthora species associated with different sources and stages in the nursery production cycle. Plants, potting media, used containers, water, greenhouse soil, and container yard substrates were systematically sampled from propagation to the field. Of 674 Phytophthora isolates recovered 28 different species or taxa were detected. The most commonly isolated species from plants were P. plurivora (33%), P. cinnamomi (26%), P. syringae (19%) and P. citrophthora (11%). From soil and gravel substrates, P. plurivora accounted for 25% of the isolates, with P. taxon Pgchlamydo, P. cryptogea, and P. cinnamomi accounting for 18%, 17%, and 15%, respectively. Five species (P. plurivora, P. syringae, P. taxon Pgchlamydo, P. gonapodyides and P. cryptogea) were found in all nurseries. The greatest diversity of taxa occurred in irrigation water reservoirs (20 taxa) with the majority of isolates belonging to ITS Clade 6, typically including aquatic opportunists. Nurseries differed in composition of Phytophthora communities across years, seasons, and source within the nursery. These findings suggest likely contamination hazards and target critical control points for management of Phytophthora disease using a systems approach.