This page is dedicated to providing current information and additional resources regarding Phytophthora ramorum (P. ramorum) and Sudden Oak Death in Oregon.
Links, files, and other resources with more detailed information are provided at the bottom of the page.
Photo credit: Sarah Navarro/ODF
Signs and Symptoms of SOD
Traditional indications of infection depend on the species. Each year, new infestations are detected, and much effort is spent in slowing the spread of this disease.
Tanoak (Notholithocarpus densiflorus) symptoms include sap bleeding, stem canker, lesions, dead tree, and foliage dieback. Tanoak is the primary host of Phytophthora ramorum in southern Oregon.
Other host species such as Douglas-fir (Pspseudotsuga menziesii), grand fir (Abies grandis), and coastal redwood (Sequoia sempervirens) show symptoms of shoot or twig dieback but are not usually killed.
Oregon-myrtle (Umbellularia californica), rhododendron (Rhododendron macrophyllum), evergreen huckleberry (Vaccinium ovatum), salal (Gaultheria shallon), snowbrush (Ceanothus velutinus), and bigleaf maple (Acer macrophyllum) will commonly show leaf blight or spots.
Other Phytophthora species and fungi can cause similar symptoms on tanoaks and other host species, which is why laboratory confirmation is required.
Dark cankers inside the bark of an infected tanoak
A bleeding trunk of an infected tanoak
Oregon-myrtle with leaf blight
Foliar dieback on tanoak
Rhododendron with spots on edges or leaf tips
Douglas-fir with shoot dieback
Photo credit: Sarah Navarro/ODF
How does Phytophthora ramorum spread?
The exact origin of P. ramorum is unknown. Sudden Oak Death was first described in California in the mid-1990s, has since spread throughout 15 counties in California, and was discovered in Oregon in 2001.
Two strains of P. ramorum are present in Oregon’s forests, the North American strain (NA1) discovered in 2001 and the European strain (EU1) discovered in 2015.
P. ramorum, the pathogen that causes SOD, thrives in Oregon’s cool, wet coastal climate and survives in infested plant material, litter, soil, and water.
Phytophthora ramorum can spread in several ways:
• Rain and fog wash spores from treetops onto tree trunks, shrubs, and other vegetation near the forest floor.
• Wind and rain carry spores from treetop to treetop across landscapes.
• People can inadvertently transport spores by moving infected plants, infected plant parts, or infested soil.
Flip through to see how Phytophthora ramorum
has spread in Curry County, Oregon.
Photo credit: Sarah Navarro/ODF
What are my SOD management options?
Sudden Oak Death affects homeowners, small woodland owners, resource managers, and conservation groups. Management options depend on your goals and location.
Please visit the Management page for information.
Reporting SOD Locations
P. ramorum can only be accurately identified by a USDA-certified laboratory using approved culture and molecular techniques.
Please visit the Reporting page for more information.
Oregon Department of Agriculture SOD Nursery Program Information Website
Oregon State University Extension Service: A Guide for Nurseries
Oregon Association of Nurseries - Safe Procurement and Production Manual
Guidelines to Minimize Phytophthora Pathogens in Restoration Nurseries
Working Group for Phytophthoras in Native Habitats.
Phytophthora Online Course: Training for Nursery Growers
In this free Oregon State University online course, you will learn about Phytophthora so that you can reduce the risk of Phytophthora disease in your nursery. Each module should take 1-2 hours to complete, although you may start and stop as often as you like. The course is free, but you can pay for an online exam for a Certificate of Mastery on Phytophthora.
The course is divided into three modules:
Module 1: Biology, Symptoms, and Diagnosis
Module 2: Disease Management
Module 3: Phytophthora ramorum
Resource Website Links
The U.S. Department of Agriculture - Forest Service Website
Information on SOD and P. ramorum in the Pacific Northwest.
OR Department of Agriculture - SOD Program Website
ODA assists in overseeing regulatory matters of the SOD quarantine area of Curry Country, Oregon.
U.S. Department of Agriculture - Animal and Plant Health Inspection Service Website
Through ongoing surveys, APHIS-PPQ continues to define the extent of the pathogen’s distribution in the US and limit its artificial spread beyond infected areas through quarantine and a public education program.
USDA/ODF SOD Management in Oregon Forests Issue Paper.
Summary of alternatives for the sudden oak death program for all forest lands in Oregon for the next five years.
OR Department of Forestry - Forest Health Program Website
The Forest Health program helps maintain and improve the health of Oregon's private and state-owned forests.
Forest Phytophthoras of the World Website
The aim of the website is to provide science-based information to aid in the understanding and management of the world’s forest Phytophthora species. Twenty of the most damaging species of forest Phytophthoras are profiled as of January 2019.
The American Phytopathological Society (APS) Website
An overview of sudden oak death, sudden larch death, and ramorum blight. Recently updated, this online article will provide a general background on the pathogen and the diseases it causes in forests and as well as nurseries.
Impacts of SOD
This report investigates current economic impacts of Sudden Oak Death in Curry County, Oregon and the potential future economic impacts through 2038.
Economic impacts from SOD on the timber industry include:
- The potential reduction in annual harvest volume of tanoak, changes in logistics of harvesting commercial conifer species, regulatory or policy decisions related to SOD, and implications for international timber exports.
Economic impacts from SOD on non-timber industries include:
- The potential impact on tribal cultural values, regional property value and aesthetics, public safety hazards, recreation, and tourism.
This report does not address the impacts of SOD on the nursery industry.
Resource Guides and Documents
Sudden Oak Death
Prevention, Recognition, and Restoration.
Used as a main source of content throughout this website, this is a guide by Oregon State University Extension Service for homeowners, small woodland owners, resource managers, and conservation groups to recognize, prevent, and manage Sudden Oak Death.
Oregon State University Extension Service
Sudden Oak Death and Phytophthora ramorum
A guide for forest managers, Christmas tree growers, and forest-tree nursery operators in Oregon and Washington.
Oregon State University - Pacific Northwest Handbooks
Tanoak (Notholithocarpus densiflorus)-Sudden Oak Death
Diagnosis and Control of Phytophthora Diseases
Rhododendron-Ramorum Leaf Blight and Shoot Dieback
Oregon Department of Forestry
SOD - Forest Health Fact Sheet
A Guide for Landowners Harvesting Tanoak
Requirements to establish a Pest-Free Production Site
U.S. Department of Agriculture - Animal and Plant Health Inspection Service
Phytophthora ramorum: Stopping the Spread
OSU & USDA in partnership with the Oregon Association of Nurseries
Testing the waters - How to test your irrigation system for the presence of Phythophthora
University of Califonia - Division of Agriculture and Natural Resources
California Oak Mortality Task Force Website
University of Califonia SOD Website
UC Cooperative Extension-Humboldt/Del Norte (UCCE) provides general information about SOD. We also monitor for symptoms of SOD in Mendocino, Humboldt, and Del Norte counties and frequently near the western edge of Trinity County