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Washington State University
WSU Puyallup Ornamental Plant Pathology

Plant Disease Research Programs

Plant Disease Research Programs

The Ornamental Plant Pathology program provides research and extension services for many plant diseases, with special emphasis on diseases caused by Phytophthora species.

Click on the image to be redirected to the program.

Sudden Oak Death
& Ramorum Blight

Symptomatic potted plants

Pacific Madrone

Pacific Madrone

Dutch Elm Disease
National Elm Trial

Puyallup National Elm Trial

Sanitation photo gallery

Sanitation for nurseries

Ensure that growing media, such as bark, is free of P. ramorum and other diseases by testing periodically using a baiting method. Only buy from trusted sources from a P. ramorum-free area. Potting media should be stored on a surface that can be cleaned easily, such as concrete. Standing water and splashing should be avoided, and the surface should be sloped to allow drainage. Media should be kept in an area away from plants and debris to avoid contamination. Do not allow staff to walk or drive in media storage area unless footwear and equipment is clean.
Place a footbath containing disinfectant in front of entrance to propagation areas to prevent contamination. In addition, cutting benches, sorting areas, machinery, tools, cutting knives, and other equipment should be sanitized before propagation. If disease inoculum is present on any of these items, it can spread through the whole crop.
Require delivery trucks to properly clean and sanitize truck bed, undercarriage, and tires between deliveries, especially if they have been in P. ramorum infested areas. Plant debris or mud from other nurseries is a potential source of contamination that can spread to your nursery. Unload incoming deliveries in an area that is clean and free of plant debris. Collect all debris from unloaded plants and delivery trucks. Properly dispose by burning, double bagging, deep burial, or steam sterilization. Do not compost this material.
Remove and dispose of all plant debris in nursery area. Use a substrate that can be easily cleaned between crops.
A layer of gravel will provide drainage to prevent water pooling and splash dispersal of disease inoculum.
Plant debris around pots is an inoculum reservoir for P. ramorum. This material should be removed to prevent infections.
smCrape Myrtle study (april 07) 058
Plant material should not be stored on bare soil, as the ground could be contaminated with Phytophthora, which can easily be splashed onto susceptible foliage.
smCrape Myrtle study (april 07) 057
Cull piles should be located in an area away from soil mixing area and plant storage areas, especially those containing high risk host material such as Rhododendron, Camellia, and Viburnum.
smConifer Inoculum Production Study 033
Plant debris can be removed using a shop-vac.
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Plants can be set out on wooden pallets, which will prevent infection from water splashing and contact with bare soil. They can be easily swept clean of accumulated plant debris.

Back to Managing Phytophthora diseases in the nursery



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Contact: Gary Chastagner, 253-445-4528 | WSU Puyallup Research & Extension Center, 2606 West Pioneer, Puyallup, WA, 98371-4998 USA
Last updated January 2, 2013

Pacific madrone survey

We are creating a database to update the madrone distribution map and learn more about the health condition of the species throughout its range.

For details about the data and representative photos to help you complete the survey, download the Pacific Madrone Assessment Guidebook, then complete the survey using one of the methods below.


We are primarily collecting data using the TreeSnap smartphone app. However, two other methods to contribute are listed below.


TreeSnap is a smartphone app. Data can be uploaded later if internet connection not available in the field. Visit the Arbutus ARME webpage for more information about using the app.

Instructions: Youtube video on how to use TreeSnap (~5 minutes).

Other ways to share observations

  1. Download the paper survey, complete, and return to WSU either by scanning/emailing, entering data in the webform on your computer, or snail mail.
  2. Webform – upload observations using your web browser (must have internet connection).