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Sudden Oak Death

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Sudden oak death -
Symptoms, this leaf was confirmed as positive for P. ramorum by Jenny Davidson. - Joseph O'Brien USDA, Forest Service
Scientific Name: 
Phytophthora ramorum Werres, de Cock & Man in't Veld (Kliejunas 2010)
Common Name: 
Sudden oak death (SOD), ramorum blight, ramorum dieback
Native To: 
Unknown; first discovered in the U.S. and Europe at approximately the same time (Scianna et al. 2003)
Date of U.S. Introduction: 
Means of Introduction: 
Potential loss of hardwood forest and increased potential of forest fire; impact to nursery and landscaping businesses (Scianna et al. 2003)


USDA. Animal and Plant Health Inspection Service.

Effective immediately, the Animal and Plant Health Inspection Service (APHIS) is expanding the Phytophthora ramorum (P. ramorum) quarantine area in Del Norte County, California. APHIS is taking this action in response to the confirmation of P. ramorum in the county on September 19, 2020. The California Department of Food and Agriculture has established an intrastate quarantine for the areas in Del Norte County that mirrors the federal regulatory requirements as specified in 7 CFR 301.92.

P. ramorum is the pathogen that causes sudden oak death, ramorum leaf blight, or ramorum dieback. Sudden oak death was first reported in 1995 on tan oak in Mill Valley, Marin County, California. Through ongoing surveys, APHIS continues to define the extent of the pathogen's distribution in the United States and uses quarantine areas and public outreach to limit its artificial spread beyond infected areas. Details on APHIS-designated P. ramorum quarantine and regulated areas and the conditions to move regulated articles are in 7 CFR 301.92 and at the APHIS website.

USDA. Animal and Plant Health Inspection Service.

The U.S. Department of Agriculture (USDA) is allocating more than $70 million to support 383 projects under the Plant Protection Act’s Section 7721 program to strengthen the nation’s infrastructure for pest detection and surveillance, identification, threat mitigation, to safeguard the nursery production system and to respond to plant pest emergencies. Universities, states, federal agencies, nongovernmental organizations, nonprofits, and Tribal organizations will carry out selected projects in 49 states, the District of Columbia, Guam, and Puerto Rico.

The fiscal year 2021 project list includes 29 projects funded through the National Clean Plant Network (NCPN). The NCPN helps our country maintain the infrastructure necessary to ensure that pathogen-free, disease-free and pest-free certified planting materials for fruit trees, grapes, berries, citrus, hops, sweet potatoes, and roses are available to U.S. specialty crop producers. In FY 2021, funded projects include, among others:

  • Asian giant hornet research and eradication efforts: $944,116 in Washington and other states;
  • Exotic fruit fly survey and detection: $5,575,000 in Florida and California;
  • Agriculture detector dog teams: $4,287,097 to programs in California, Florida, and nationally to support detector dog teams;
  • Honey bee and pollinator health: $1,337,819 to protect honey bees, bumble bees and other important pollinators from harmful pests;
  • Phytophthora ramorum (sudden oak death pathogen) and related species: $513,497 in 14 states and nationally for survey, diagnostics, mitigation, probability modeling, genetic analysis, and outreach;

USDA will use $14 million to rapidly respond to invasive pest emergencies should a pest of high economic consequence be found in the United States. Learn more about the Plant Protection Act, Section 7721 on the USDA Animal and Plant Health Inspection Service (APHIS) website.

USDA. ARS. Tellus.

Potatoes and oak trees don’t have a lot in common, but there is one thing, and it isn’t good – a fungal-like plant pathogen in the genus Phytophthora. One of the many invasive pathogens contained in this genus, P. infestans, was responsible for the Irish potato famine. Since the mid-1990s, though, Phytophthora has been attacking forest trees along the West Coast, with the pathogen P. ramorum, also known as "sudden oak death" (SOD). SOD was first detected in the San Francisco Bay Area; it has since spread throughout California. In 2001, SOD was discovered in southwest Oregon where it infected tanoaks trees. The discovery led to the formation of an interagency team that included researchers from the Agricultural Research Service (ARS) and Oregon State University (OSU), to develop strategies to mitigate the impacts of SOD.

Distribution / Maps / Survey Status

USDA. FS. Northern Research Station.

Select the non-indigenous forest pest to view maps depicting state and county distribution. Produced by: USDA, FS, Forest Health Protection, and its partners.

University of Georgia. Center for Invasive Species and Ecosystem Health.
Provides state, county, point and GIS data. Maps can be downloaded and shared.
California Oak Mortality Task Force.


California Department of Food and Agriculture. Plant Health Division. Pest Exclusion Branch.

Federally Regulated

U.S. Government Printing Office. Electronic Code of Federal Regulations.

USDA. APHIS. Plant Protection and Quarantine.

A Federal Order is a legal document issued in response to an emergency when the Administrator of APHIS considers it necessary to take regulatory action to protect agriculture or prevent the entry and establishment into the United States of a pest or disease. Federal Orders are effective immediately and contain the specific regulatory requirements.

USDA. Animal and Plant Health Inspection Service.

See what states have a federal quarantine for any of the targeted Hungry Pests, and identify which pests or diseases are at greatest risk due to a suitable habitat. In addition to federal quarantines, state-level quarantines might apply see State Summaries of Plant Protection Laws and Regulations (National Plant Board).


University of Georgia. Center for Invasive Species and Ecosystem Health.

California Oak Mortality Task Force.


Google. YouTube; University of California Cooperative Extension. Sonoma County.

Selected Resources

The section below contains highly relevant resources for this species, organized by source. Or, to display all related content view all resources for Sudden Oak Death.

Council or Task Force

California Oak Mortality Task Force.

European Network on Invasive Alien Species.
See also: NOBANIS Fact Sheets for invasive alien species of the European region, covering both animals and plants, as well as microorganisms
European and Mediterranean Plant Protection Organization.
Massachusetts Introduced Pests Outreach Project.

National Plant Diagnostic Network.

You can become a more effective First Detector by familiarizing yourself with invasive target pests and pathogens known to exist in the U.S. If you think you have encountered one of the species or disease complexes listed, report its presence.

Nature Conservancy. Don't Move Firewood.
IUCN. Species Survival Commission. Invasive Species Specialist Group.
University of California - Berkeley. Cooperative Extension; USDA. Forest Service.

Ontario's Invading Species Awareness Program (Canada).

North Central Region Pest Management Center.

See also: Pest Alerts for more resources

Federal Government
International Government

Forestry Commission (United Kingdom). Forest Research.

State and Local Government

Maryland Department of Agriculture.

Minnesota Department of Agriculture.

Connecticut Agricultural Experiment Station.

Indiana Department of Natural Resources. Entomology and Plant Pathology.

Georgia Forestry Commission.

North Carolina Department of Agriculture and Consumer Services. Plant Industry Division. Plant Protection Section.
Oregon State University. Extension Service.
A guide for homeowners, small woodland owners, resource managers, and conservation groups to recognize, prevent, and manage Sudden Oak Death.

Michigan State University. Integrated Pest Management Program.

See also: Forecasting Invasion Risks for more factsheets

University of Massachusetts Extension. Landscape, Nursery, and Urban Forestry Program.

University of California - Berkeley.
Columbia University. Center for Environmental Research and Conservation.

Clemson University. Regulatory Services.

University of California. Statewide Integrated Pest Management Program.
See also: Pest Notes are peer-reviewed scientific publications about specific pests or pest management topics, directed at California's home and landscape audiences.

University of Arkansas. Cooperative Extension Service.

See also: Common Disease Problems for more fact sheets

University of California - Riverside. Center for Invasive Species Research.