FY12-13 Research Projects

The following projects are underway at the National Ornamentals Research Site at Dominican University of California (NORS-DUC). They have been funded with this Fiscal Year 2012-2013 farm bill monies, pending completion and approval through the California Pesticide registration.

If NORS-DUC is funded through the farm bill next fiscal year, additional monies will be made available for research. See Call for Proposals.

TITLE: Risk of Root-to-Root Spread of Phytophthora ramorum in Ornamental Production Nurseries

RESEARCHERS: Gary Chastagner and Marianne Elliott, Washington State University Research and Extension Center, Puyallup, WA 98371, (253) 445-4528, Phone - Gary: (253) 445-4528; Phone - Marianne: (253) 445-4596, [email protected], [email protected]; Steve Tjosvold, University of California Cooperative Extension (UCCE), Watsonville, California 95076, General Office: (831) 763-8040, Direct Office: (831) 763-8013, Fax: (831) 763-8006, [email protected]; Nina Shishkoff, Foreign Disease Weed Science Research Unit, USDA/ARS, Fort Detrick, MD 21702, Phone: (301) 619-2877, Fax: (301) 619-2880, [email protected]

Laboratory studies have shown that Phytophthora ramorum is able to colonize and infect root systems of a number of plants. Studies have also shown that this pathogen is able to sporulate on infected root tissues of Viburnum, Camellia and Rhododendron. The epidemiological significance of root infections in production nurseries is unknown. We are proposing to examine the root-to-root spread of P. ramorum on Viburnum tinus in ground or raised beds at the NORSDUC research site. This research will provide a better understanding of the risk associated with this pathway of spread.


TITLE: Development and application of an epidemiological framework for management of Phytophthora ramorum on Rhododendron in nursery settings  

RESEARCHERS: Niklaus J. Grunwald, Horticultural Crops Research Laboratory, USDA ARS, 3420 NW Orchard Ave., Corvallis, OR 97330, Phone: (541) 738-4049, Fax: (541) 738-4025, [email protected]; Jennifer L. Parke, Dept. of Crop and Soil Science, 3017 Agriculture and Life Sciences Building, Oregon State University, Corvallis, OR 97330, Phone: (541) 737-8170, Fax: (541) 737-5725, [email protected]; Christopher A. Gilligan, School of Biological Sciences, Department of Plant Sciences, University of Cambridge, Downing Street, Cambridge, CB2 3EA, U.K., [email protected]

Epidemiological theory provides a useful toolbox to identify criteria for invasion of pathogens in nursery settings.  Using a combination of intensive experimentation and established epidemiological theory the current project aims to develop and test the epidemiological framework necessary for evaluating different management scenarios within nurseries for the sudden oak death pathogen Phytophthora ramorum. Work will include development and validation of a spatially-explicit epidemiological model for invasion by P. ramorum within nurseries to screen potential management scenarios and, once developed, evaluation of different management scenarios for control of P. ramorum in nursery settings.


TITLE: Determination of Phytophthora ramorum threshold inoculum levels in irrigation water needed for infection of nursery hosts                                

RESEARCHERS: Gary Chastagner and Marianne Elliott, Washington State University, Research and Extension Center, 2606 West Pioneer, Puyallup, WA 98371 Contact Information: Chastagner - Phone: 253-445-4528, Fax: 253-445-4621, [email protected] Elliott - Phone: 253-445-4596, Fax: 253-445-4621, [email protected]

Spread of plant disease via contaminated irrigation water in a nursery or greenhouse is an issue that many growers face. Irrigation water is commonly recycled or pumped from nearby ponds and streams, and both of these sources can become contaminated with Phytophthora and Pythium species. Nationally, there is concern about the potential risk of spreading P. ramorum via the irrigation of plants with water from infested streams. We are proposing to determine inoculum thresholds in irrigation water that are necessary for infection of three common hosts of P. ramorum under simulated nursery conditions. Nationally, there is concern about the potential risk of spreading Phytophthora ramorum via the irrigation of plants with infested water. This pathogen has spread from nurseries into waterways in a number of states. In some instances water from these infested waterways is used to irrigate plants on farms, nurseries and in landscapes. In Washington state, WA Dept. of Ecology records (May 2009) indicate that 46 entities have rights to use water from the Sammamish River in King County, WA to irrigate almost 2,800 acres of land, including parks, farms, churches, and nurseries. Phytophthora ramorum has been found in this river since 2006. Research in CA and Europe has shown that plants in nurseries can be infected when overhead irrigated with water infested with P. ramorum (Tjosvold et al 2006, Werres et al. 2007). However, it is unclear how inoculum levels in these situations relate to the apparent low levels of inoculum in nursery- related infested streams. Further studies are needed to determine more precisely what level of inoculum is needed for infection of plants or infestation of soil to occur via irrigation. This information will make it possible to estimate the risk of spreading P. ramorum from the Sammamish River and other infested waterways via the irrigation pathway. Being able to quantify inoculum levels in waterways and understand the inoculum threshold necessary for infection will assist the nursery industry and regulatory agencies in making decisions about the level of risk in using P. ramorum infested water for irrigation in locations where the pathogen has spread from positive nurseries into streams.

TITLE: Assessment of nursery crop-induced alteration in pathogenicity of Phytophthora ramorum

RESEARCHERS: Takao Kasuga, USDA-ARS, Davis, CA 95616, Phone (530) 752-0766, Fax (530) 754-7195, [email protected]; David M. Rizzo, Department of Plant Pathology, University of CA, Davis, CA 95616, Phone: (530) 754-9255, Fax (530) 752-5674, [email protected]; Matteo Garbelotto, Department of Environmental Science, Policy, and Management, University of CA, Berkeley, CA 95720, Phone (510) 643-4282, Fax: (510) 643-5436, [email protected]  


TITLE: A comprehensive study of populations of Phytophthora ramorum in plants, soil and water during the course of a year at the NORS-DUC nursery research facility

RESEARCHERS:  Matteo Garbelotto, Department of Environmental Science, Policy, and Management, University of CA, Berkeley, CA 95720, Phone (510) 643-4282, Fax: (510) 643-5436, [email protected]  


TITLE: Validating commercial formulation of Trichoderma asperellum against Phytophthora ramorum-infested soil

RESEARCHER: Tim Widmer, USDA-ARS, Ft. Detrick, MD 21702, Phone (301) 619-7338; Fax: (301) 619-2880,[email protected] usda.gov