Sudden Oak Death Syndrome (SODS)

What is Sudden Oak Death Syndrome?

Sudden Oak Death Syndrome, or SODS, is a forest disease caused by Phytophthora ramorum, a fungus-like pathogen. It can be fatal to some plants, including coast live oak, black oak, Shreve oak and tanoak. P. ramorum affects different species in a variety of ways, and is spread through a wide number of host species, including the California bay laurel and Rhododendron varieties. The pathogen itself is spread by wind blown rain.

What trees does Sudden Oak Death affect?

Currently there are 26 species of trees and plants which are known to be susceptible to P. ramorum. This list is constantly evolving as scientists find out more information. For a current list of host species, click here.

What are the symptoms?

Symptoms of SODS vary from species to species. Infection may occur on the trunk, branches, and/or leaves. Cankers, infections on the woody portions of trees, are the most damaging. Diseased oaks are also often attacked by other pest organisms. Beware! Sudden Oak Death is easily confused with a number of other disorders because the symptoms are very similar. A laboratory test must be performed to conclusively identify the disease.

Where is SODS found?

SODS has been found all along the west coast. It was first found in California in 1995. Infected plants have been found in 12 counties: Humboldt, Mendocino, Sonoma, Napa, Solano, Marin, Contra Costa, Alameda, San Mateo, Santa Clara, Santa Cruz, and Monterey. SODS is generally found in two forest types: the under story of coast redwood and in coastal evergreen forests.

Where can I find more information?

The following links provide good information about Sudden Oak Death Syndrome:

The California Oak Mortality Task Force

Acterra; Resource Sheet on Sudden Oak Death

City of Greenbrae, Marin County, Information on Sudden Oak Death