Sudden Oak Death is a tree disease caused by the fungus-like plant pathogen Phytophthora ramorum. First recognized in the mid 1990s, the disease kills some oak species (primarily coast live oak, Quercus agrifolia, and an oak relative, tanoak, Notholithocarpus densiflorus) and has had devastating effects on coastal forests in California and Oregon. The pathogen also infects rhododendrons, camellias, and other common horticultural plants, causing ramorum blight. In the UK and Ireland, the pathogen is causing extensive damage on Japanese larch (Larix kaempferi) in plantations.

Phytophthora ramorum was inadvertently introduced to California forests on nursery stock and, as an invasive species, is quarantined in over 60 countries with restrictions enforced on shipments of nursery stock and other host plant materials. For an introduction and background on Sudden Oak Death/P. ramorum read more here.

Relatives of P. ramorum, other Phytophthora species are damaging native and ornamental vegetation throughout California. Unintentional pathogen introductions are an acute concern for restoration of sensitive habitat where restoration nursery stock may serve as a pathway for pathogen introduction into rare, threatened or endangered species habitat. Read more about other Phytophthora species found in native habitats, native plant nurseries, and restoration sites here.


SOD Blitz Press Release: UC Berkeley announces programs for  professional arborists, urban foresters, licensed tree care specialists, pesticide applicators, and qualified government and NGO employees.

“Conducting Activities Related to Monitoring, Extension, Management and Mitigation of the Sudden Oak Death Disease Caused by Phytophthora ramorumRequest for Proposals is now available. Deadline is February 15, 2019.

2018 stream monitoring in CA finds 4 P. ramorum-positive waterways, including new rivers in Monterey and Del Norte Counties. Read more…

Oregon forest and stream monitoring efforts find new P. ramorum infestations, including EU1 populations, in 2018. Read more…

The number of P. ramorum-positive nurseries in CA declined from 16 in 2017 to 11 in 2018; six nurseries are under interstate shipping compliance under Federal Order DA-2014-02. Read more…

Sampling continues in OR and WA nurseries, with over 4,000 samples processed in 2018. Read more…

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Help stop the spread of forest pests – including Sudden Oak Death – on firewood! Check out the website of the California Firewood Task Force.

Calendar of Events

6/25-27 – “Healthy Plants in a World with Phytophthora” – The Seventh Sudden Oak Death Science and Management Symposium; Presidio, San Francisco, CA; for more information, view the event website

07/16 – California Forest Pest Council Insect and Disease Field Tour, Fort Bragg

View more details on upcoming events in the latest newsletter…

The California Oak Mortality Task Force is a task force under the California Forest Pest Council.