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Washington State University
WSU Puyallup Ornamental Plant Pathology

SOD Public Inquiry Guide

Tips to answer calls or questions from arborists, landscape professionals, homeowners, or the general public.

How to check for symptoms and the need to sample for Phytophthora ramorum

On trees:

Bleeding symptoms only occur on coast live oak, California black oak, Shreve’s oak, and tanoak. These species are not native to Washington State and are rarely seen here as ornamentals. Bleeding on maple, Douglas-fir, or other foliar hosts (with the exception of poison oak and Pacific yew) usually indicates a different causal agent. Leaf and twig symptoms do not occur on hosts in the red oak group, but may on tanoak and canyon live oak. Garry oak (white oak group) is not considered to be a host and only develops minor symptoms.

There are many diseases and pests that produce symptoms similar to those of Sudden Oak Death. For a full list with descriptions, see the Pest Identification document. Compare symptoms with those in the diagnostic guide or consult with a landscape professional for diagnosis.

On shrubs and other plants:

Phytophthora ramorum produces leaf blotches, twig cankers, and shoot die-back on many plants. In some cases the shoot die-back may be severe enough to kill the plants (e.g., huckleberry and madrone), but in general they do not usually die as a result of P. ramorum infection.

Foliar hosts may be damaged by fungi, other Phytophthora species, insects, the sun, or other environmental conditions, and these can cause symptoms similar to those of P. ramorum. This can make it very difficult to identify the pathogen on these species.

How to determine whether to submit a sample for testing:

Though you will not be able to identify SOD in the field, you can screen samples and decide if they should be sent in for further testing. When a client suspects Sudden Oak Death, use the key in this binder as a guide to determine if the sample should be submitted. There are also examples of what P. ramorum symptoms look like on a few common native and ornamental host plants in Washington State.

If you determine a sample should be submitted for testing the sample should be sent to WSU Puyallup for free diagnosis (postage not included). Please follow the approved procedure found at

What is the status of SOD in Washington State?

In June 2003, Phytophthora ramorum, the causal agent of sudden oak death was confirmed for the first time in Washington.

Since that time the Washington State Dept. of Agriculture (WSDA) has tested over 100,000 plants in hundreds of nurseries as part of the national SOD survey and trace forward surveys from production nurseries found to be infected with the pathogen.  As of March 31, 2014, APHIS no longer imposes P. ramorum regulatory requirements for the interstate movement of host nursery stock from certain nurseries located in the regulated areas of California, Oregon, and Washington. Nurseries that have not had P. ramorum detected in annual surveys since March 31, 2011 will not be required to be inspected and certified in order to ship regulated and associated host plants interstate. Also, nurseries located in regulated areas that do not contain, and that do not ship nursery stock listed as proven host taxa or as associated plant taxa are no longer required to comply with 7CFR 301.92. APHIS will, however, continue to regulate all interstate shipping nurseries located in quarantine areas of California and Oregon, including those that contain only non-host nursery stock.


Visit the WSDA SOD website for more information –

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.
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).