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WSU Puyallup Ornamental Plant Pathology

2015 Pr detections

From January 1 to June 3, 2015, P. ramorum was reported in 10 nurseries (OR 8, WA 1, VA 1), one commercial landscape (LA), and a botanical garden (WA) in non-quarantine areas. P. ramorum was detected in Camellia (2), Kalmia (1), Mahonia (1), Osmanthus (1), Pieris (10), Rhododendron (40), Viburnum (4), Vinca (2), and soil samples (8). Four of the nurseries ship interstate and are in the USDA APHIS compliance program (started spring, 2014; Federal Order DA-2014-02). The Confirmed Nursery Protocol is underway in all nurseries and no findings were made at trace-forward sites. Detections at the WA botanical garden are in managed landscapes; survey and disinfestation procedures are underway.

For more information on this and other news items, read the COMTF monthly newsletter.

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.
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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.
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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).

Pacific Madrone Research

Pacific Madrone Research


Welcome to the WSU Pacific Madrone Research webpage!

The purpose of this webpage is to highlight the aim of our madrone research, describe our ongoing projects, and share important information for conserving the Pacific madrone.

We also invite you to participate in our research by joining the Arbutus ARME and subscribing to our newsletter. More information is available below, but feel free to contact us if you have any additional questions.

Pacific Madrone

Pacific Madrone

Madrone (arbutus, madrona or madroño) is an important tree in the Pacific Northwest because of its cultural and ecological value. For example, madrone is an important part of our cultural heritage because the berries were used widely as a food source or even as bait for steelhead fishing. Ecologically, Pacific madrone is an important pioneer species and its tolerance to salt water allows it to occupy many areas that would erode otherwise. Click here to learn more about Pacific madrone.


Madrone is a keystone species of the Pacific Northwest. Current populations range from the coast of central California into southern British Columbia. However, the distribution of Pacific madrone is expected to shift with changes in climate. Click here for more information about the distribution. Additional information about some of the region’s Champion Trees is also available here.


Research Aim

Research is critical to advance knowledge and conserve the madrone in the Pacific Northwest. Populations of this keystone species are already under threat from changes in the climate and pests and diseases. For example, madrone leaf blight is a major disease affecting madrone in western Washington and Oregon. In this regard, identifying populations that are most tolerant to leaf blight is a priority for our research program.

One of the primary aims of our program is to promote the health and sustainability of Pacific madrone. There are two ongoing studies designed to help accomplish this aim:

Common Garden Study

Madrone trees from various seed sources, collected throughout its range, were planted at sites ranging from California to British Columbia. These ‘Common Gardens’ are monitored annually to identify the genotypes best suited for each region. More information about the study is available here.

Pacific Madrone Survey – We need your help!

You’re invited to join the Arbutus ARME and contribute to research about the range and health conditions of Pacific madrone! These data will be valuable for identifying vigorous trees with resistance to leaf blight in wild populations and monitoring for the emergence of novel threats, such as new pests and diseases. Anyone is welcome to participate.

Additional resources and research outcomes of our program are available here.

Arbutus ARME


The Arbutus ARME is a ‘citizen science‘ program that was established through a partnership between WSU and Seattle Parks and Recreation in 2019.

Contribute to Research!

You can contribute to research to advance knowledge and help conserve the Pacific madrone.

Join the Arbutus ARME

Visit our Arbutus ARME webpage to join the Arbutus ARME and subscribe to the newsletter.

More Information

Contact us for more information, research updates, or to learn about the opportunities to contribute.


Previous Events

“The Future of Pacific Madrone” Mini-conference held April 19-20 2016 at WSU Puyallup.

Upcoming Events

Check back soon or contact us about upcoming events to learn more about our Pacific madrone research or the opportunities to meet others in the Arbutus ARME.

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