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Washington State University
WSU Puyallup Ornamental Plant Pathology

Ornamental Plant Pathology

Ornamental Plant Pathology


Welcome to the WSU Puyallup Ornamental Plant Pathology program. We are part of the Department of Plant Pathology and based in the WSU Puyallup Research and Extension Center.

The purpose of this website is to share information and resources about managing diseases of ornamental and native plants in Washington State. Please explore our website to learn more about our research and extension programs.


Spring 2021

  • Our program seeks citizen scientists to join us in a stream monitoring effort on the east side of the Cascades this spring and summer! Click here to find more information or sign up to participate.

Winter 2021

  • We engaged with many partners to design and shape the Forest Health Watch program. Check it out to learn more about the opportunities to partner and contribute to more forest health research.

Research Programs

Much of our research is focused on reducing the impacts of pests and diseases on industries involved in the trade of ornamental bulbs, lavender, and Christmas trees. We also conduct applied research to increase the post harvest longevity of Christmas trees.

Our program also conducts research about diseases caused by Phytophthora (fy-toff-thor-uh) species. For example, we work closely with federal and state agencies to manage and monitor Phytophthora ramorum, the invasive species that causes Sudden Oak Death and ramorum foliar blight. We also conduct research about diseases such as Pacific madrone leaf blight and Dutch Elm Disease.

Major aims of our Sudden Oak Death Research Program are to serve stakeholders in the state of Washington with:

  • Learning about Phytophthora species by providing information and resources,
  • Managing the impact and spread of Phytophthora species in nurseries, gardens, and landscapes,
  • Monitoring streams for early detection and baseline information about Phytophthora species,
  • Aiding local site eradication of Phytophthora ramorum with advanced steaming protocols and equipment.

Emerging Plant Health Concerns

Our program has summarized a few plant health concerns that have emerged recently. Access information about these plant health issues by clicking on the images below.

We will continue to update this section of our website. Please feel free to contact us if there are other emerging issues that you would like more information about.

Education Programs

Nursery Inspector

Citizen Science – Opportunities to Contribute to Research

Help Advance Knowledge

Interested in advancing knowledge and developing solutions to plant health issues in the Pacific Northwest? Our program currently hosts two citizen science projects that anyone can participate in.

Citizen science is a term for research projects that involve the general public in data collection. Visit our citizen science webpage to learn more about the current opportunities to contribute to our research.

Youth volunteers contributing to stream monitoring and research

Job, Internship and Volunteer Opportunities

Join our Community

Visit our jobs page to find out more about the opportunities to join the Ornamental Plant Pathology research program.

Check back frequently as we have many projects with seasonal opportunities.

WSU Puyallup Personnel

Support Our Program

Phytophthora culture

Increase our Impact

Support our program to help us conduct research and provide more services for Washington’s residents and industries through tax-deductible gifts to WSU.

WSU Sudden Oak Death Program

Sudden Oak Death Research and Education Program


Welcome to the WSU Sudden Oak Death program website. Here you will find information about Sudden Oak Death and other diseases caused by Phytophthora ramorum. We aim to provide resources and services for educators, managers, industries and landowners.  More information about the services we provide are available at the links below.

  • Education– nursery management, symptom identification guides, information for Master Gardeners, events.
  • Research – host testing, fungicide testing, population genetics, disease management.
  • Monitoring – stream monitoring, population genetics of P. ramorum in WA.

What is Sudden Oak Death?


Sudden Oak Death is a disease caused by Phytophthora ramorum, a non-native microbe that harms plants (plant pathogen).


Sudden Oak Death has killed hundreds of thousands of oak and tanoak trees in California, and it has affected larch plantations in the UK.

Sudden Oak Death


APHIS 2016 SOD Quarantine Map
Areas under active federal quarantine


Phytophthora ramorum has only been recovered from Washington, California, Oregon, several European countries, the United Kingdom, and Vietnam. In Washington and Oregon, P. ramorum is found in mainly ornamental plant nurseries.

Washington State

Phytophthora ramorum has been present in Washington state since 2004, yet no forest outbreaks have occurred as they have in California, Oregon, and the UK. This may not be the case with the next invasive plant pathogen, therefore the use of Best Management Practices (BMPs) for growing clean plants is important for nurseries to adopt.

Best Management Practices


Information about Phytophthora ramorum is available for various stakeholders in our Education Program.

Visit our webpage for Nursery Productions if you are looking for Best Management Practices for managing Phytophthora ramorum. These practices are also useful for managing other Phytophthora diseases, such as those that cause root disease, which can be more damaging than P. ramorum on their hosts.

Visit our Phytophthora ramorum Symptom ID Guide for more information about recognizing Phytophthora disease issues.

Lifecycle of Phytophthora ramorum

Additional Information and Resources

What’s new:

APHIS Confirms Detection of Phytophthora ramorum-Infected Plants in Commerce 7/10/2019

Are Invasive Plant Pathogens Moving into the Puyallup River Watershed?– A presentation from the Puyallup River Science Symposium 12/7/2018

Critical Control Point assessment for nurseries – Contact us to learn about our service to help identify Critical Control Points in your production.

More reading:

Let us know if you see broken links or other problems.

Contact Us | WSU Puyallup Research & Extension Center, 2606 West Pioneer, Puyallup, WA, 98371-4998 USA

Education Program

Sudden Oak Death Education Program


Rhododendron plants at Puyallup farm

WSU Puyallup developed an program to provide educational material and activities relating to P. ramorum and other Phytophthora diseases throughout Washington with funding provided by the USDA Forest Service and National Plant Diagnostic Network.

Below we provide educational resources for homeowners, land managers, Master Gardeners, and nursery professionals. These resources include guides for symptom recognition, early detection and management of Phytophthora diseases such as SOD. Early detection is key for protecting Washington’s nursery, landscape, and forest industries from the effects of P. ramorum and other invasive plant diseases.

Developing Best Management Practices (BMPs) for nurseries are another component of the WSU SOD Education Program. Proper use of BMPs will help nurseries prevent or mitigate infestations by P. ramorum and other invasive plant diseases.

The WSU Puyallup program also provides opportunities for local students to obtain research experience by working with us on various projects related to Phytophthora.

General Information

Sudden Oak Death

Hosts and identification

Phytophthora diseases

Diagnostics – Do I have Phytophthora ramorum?

Information for Specific Audiences


Click on the images below to find the information most relevant to you.

Información en español

Plant Nursery Professionals

Nursery Inspector

Garden Managers, Staff & Volunteers

Rhododendron plant at Bloedel Nature Reserve

Forests Managers & Christmas Tree Growers

Christmas tree manager

Native Plant Producers & Managers


and Learners

More Information and Resources

WSU Resources

SOD Research Program

WSU Sudden Oak Death Research Program Brochure

SOD Nursery Management

WSU Sudden Oak Death Nursery Management Brochure

SOD Stream Monitoring

WSU Stream Monitoring Brochure

External Resources

OSU Extension SOD Forest Health Note UC Davis SOD Management Homeowners

USDA SOD Hungry Pests Poster UC Davis SOD Management in Nurseries

Sudden Oak Death Pest Notes Defra SOD Guidelines for Nurseries

Defra SOD Management in Parks and Gardens




Drainage water