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ARS Home » Pacific West Area » Corvallis, Oregon » Horticultural Crops Disease and Pest Management Research Unit » Research » Research Project #439181

Research Project: Detection and Management of Phytophthora species in Nurseries and Greenhouses

Location: Horticultural Crops Disease and Pest Management Research Unit

Project Number: 2072-22000-045-014-S
Project Type: Non-Assistance Cooperative Agreement

Start Date: Sep 1, 2020
End Date: Oct 31, 2024

1. Continue to identify new host-pathogen associations for Phytophthora spp. on ornamental crops and then maintain a permanent collection of Phytophthora spp. associated with ornamental plants as a resource for future investigations. 2. Improve detection methods of Phytophthora spp. on nursery-grown plants to prevent movement of these pathogens to landscapes and fields. 3. Evaluate management strategies for Phytophthora spp. on ornamental plants.

Objective 1: Samples of diseased ornamental plants and cultures of Phytophthora species from ornamental plants will be collected and received from growers around the country and through collaborations with organizations and colleagues. Isolates from the samples will be added to an existing collection for long-term storage and preservation. This collection will be used to identify new host-pathogen associations. Isolates will be identified initially using morphological and physiological characters, and then molecular characters will be used to validate and verify identifications. Experiments to confirm pathogenicity in new host-pathogen associations will be conducted in the greenhouse. Objective 2: Plants in production trays and flats, coming from or at production facilities, will be assayed for Phytophthora spp. using several different methods being studied in the lab. The goal is to detect the pathogens in the production pathway before they are moved landscapes and fields. Objective 3: Cultivars of floriculture plant species will be screened for resistance to species of Phytophthora. Host plant resistance has the potential to effectively manage Phytophthora diseases over the long term in landscapes and fields. Currently, work is being done with commercial flower companies to develop annual vinca plants that are resistant to P. nicotianae, which causes Phytophthora foliage blight and root rot. Using an established host-pathogen system, new fungicides that have been developed recently or are under development will be evaluated and compared to some of the standard products already in the marketplace. Registered biofungicides will also be evaluated for efficacy and other novel disease management strategies will be evaluated when they are recognized.