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WSU Research Facility

Since 2003, the WSU Puyallup Ornamental Plant Pathology Program has conducted research on Phytophthora ramorum related to host range, epidemiology, and evaluating potential control options.

In response to industry concerns, WSU built a quarter-million-dollar biocontainment facility at Puyallup. This facility has increased the capacity of WSU to address critical research questions related to the establishment, host susceptibility, spread and management of P. ramorum. A molecular lab has also been established to enhance research relating to the detection, spread, and genetics of this pathogen.

various small plants and shrubs seen through a square window with metal surrounding it. Centered in the frame is a shrub with domed, dark pink flowers. The ceiling of the chamber containing the plants is made of six square fluorescent lights held together with metal strips.
Plants in Biocontainment Facility

Research

shiny green leaves with severe phytophthora lesions
seven leaves on a grid with a pink ruler above them. The three leaves on the bottom are covered in lesions and severely yellowed. The four leaves on the top have smaller lesions. Second from the right leaf in the top row has a brown lesion along nearly its entire midrib and discoloration can be seen spreading outward.
Camellia japonica leaf scoring
a rhododendron shoot with green leaves and new buds sticking up from the top. Just below the top of the stem and going downward to 3/4 of the way to the bottom of the frame has turned dark brown, a symptom of shoot dieback.
green leaves attached to brown stems. at the end of the stem on the left are three brown catkin-like flowers, though the end of the topmost flower is still greenish. All of the visible leaves have lesions at some point along the midrib.
small plants in square black pots. the older, darker green leaves have brown phytophthora lesions in one or more places.

Phytophthora ramorum poses substantial challenges to industries and land managers in the Western United States, including Washington State. Therefore, much of our research is dedicated to providing guidance and solutions in terms of risk assessment and management.

Below we provide information about our research in four broad categories. Click on the images or links below to find more information about the research we have conducted in each category.

on newspaper, leaves in horizontal rows with their stems facing the right. Third from the right, the bottom two leaves are yellow. Small brown dots can be seen on the left three rows. these are lesions that formed after the leaves were scored and exposed to phytophthora.

Management of P. ramorum

Steam Treatments

four people standing behind a pile of used pots covered in a large black tarp held down with long green sandbags.

Biological Control

a forest with tall straight conifers and scattered shrubs on the ground. On the tree closest to the camera is a red and white sign. At the top it says "Stop the spread of sudden oak death"

Host Testing

Conifer Susceptibility

a pile of straight lengths cut from trees. all branches have been cut off and they are wrapped in yellow or white tags.

PNW Broadleaf Hosts

a cluster of Pacific Madrone leaves. They are green, but the edges are ragged and brown lesions are pervasive on each leaf.

Rhododendrons

a ball-like cluster of ruffly pink rhododendron flowers. the leaves visible are yellowing.

Nursery Management

Fungicide Evaluation

young rhododendron plants in square-topped black pots with round bottoms, which have been placed in clear plastic cups. Each pot is labeled with a set of numbers on a sticker. the pot closest to the middle of the frame has wilting, yellow and brown leaves.

Disinfectants

two clear glass beakers, one slightly larger than the other. They are labeled in sharpie: "DF" and "Tanoak". In the bottom of the beakers are tan seeds. a wet paper towel has been placed on top of the seeds, and then the tops of the beakers were sealed with parafilm.

Nitrogen Fertility

Magenta Rhododendron flowers with shiny medium-green leaves

Biology and Spread

Biology

six petri dishes filled with a pale orange nutrient agar in two rows. each is labeled above with a number and an alphanumeric code. in the center of each dish, a small round sample of phytophthora was placed. Outward from each sample has grown a unique pattern of mycelia, some of which can be seen on top of the agar and some only growing within it.

Waterway Testing

looking upriver at a gravel bar just past a curve in the banks with a dense forest on the other side.

Population Genetics

a set of four horizontal graphs stacked vertically with green and orange spikes
PPO Home > Sudden Oak Death Research and Education Program > Sudden Oak Death Research

Research Reports and Publications

General

  • An Overview of Phytophthora ramorum in Washington State (PDF)
    Gary A. Chastagner, Katie Coats, and Marianne Elliott
    In Frankel, S.J.; Kliejunas, J.T.; Palmieri, K.M.; Alexander, J.M. tech. coords. 2013. Proceedings of the Sudden Oak Death Fifth Science Symposium. Gen. Tech. Rep. PSW-GTR-243. Albany, CA: U.S. Department of Agriculture, Forest Service, Pacific Southwest Research Station. 169 p.

Management

Nursery Management

Host Susceptibility

Biology and Spread

WSU Puyallup Research & Extension Center
2606 West Pioneer, Puyallup, WA, 98371-4998 USA
Last updated 9/25/2025