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Sudden Oak Death

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Sudden Oak Death in Santa Clara County
What you should know and can do to prevent spreading

By Shannon Dinis, ISA Certified Arborist

Sudden Oak Death is a disease that is becoming very prevalent in Santa Clara County and many other coastal counties in California. Known cases of the disease range from Monterey to Humboldt Counties. The number of counties is likely to increase as more research is done. The spread of the disease is mainly found in coastal areas that receive plenty of rainfall and fog because the fungus needs a moist environment to spread its spores. This disease primarily affects tanoaks (Lithocarpus densiflorus), coast live oaks (Quercus agrifolia), and various other oak and tree species of the coastal forest.

Sudden Oak Death is caused by a fungus called Phytophthora ramorum which infects the water flow system of the diseased trees. Eventually, the fungus spreads around the entire tree blocking the flow of water from the roots to the leaves which dehydrates it and causes it to die. Along with affecting the water flow system of oak trees, P. ramorum is also known to cause leaf infections on California bay trees (Umbellularia californica), rhododendron, redwood, and many other tree and plant species. In the case of leaf infection, the fungus does not kill the plants; rather it causes branch dieback and discoloration of the leaves. Bay trees are known to spread the spores of P. ramorum and so tanoaks and oaks near infected bay trees usually become infected as well.

Click here for a complete copy of this article by Shannon Dinis (PDF file).  Shannon is currently pursuing her Masters in Conservation Biology at San Jose State University. She worked for WECI as a contractor in PG&E’s vegetation management program. She is also the South County Area Coordinator for the Santa Clara County FireSafe Council.

Sudden Oak Death References:

To learn more about Sudden Oak Death and the California Oak Mortality Task Force, visit www.suddenoakdeath.org

A Homeowner’s Guide to Sudden Oak Death (PDF File)

Homeowner FAQs

CAL FIRE Tree Notes: Oak Mortality Syndrome: Sudden Death of Oaks and Tanoaks (PDF File)

Click here and here for more on Sudden Oak Death and fire (PDF Files)

To learn more about possible fungicidal treatments, visit www.californiaoaks.org/html/oak_tree_care.html. 

Sudden oak death: endangering California and Oregon forest ecosystems (PDF File)

Sudden Oak Death Online Symposium

Sudden Oak Death Tree Removal Program:

SCFSC has a Chipping and Sudden Oak Death (SOD) Tree Removal Program for selected Communities at Risk.  << New

12/30/09

Funding provided by National Fire Plan grants from the USDI Bureau of Land Management, the USDA Forest Service and the US Fish and Wildlife Service through the California Fire Safe Council. Our Community Outreach, Education and Youth programs and other council activities are also funded by grants and donations from local agencies, companies, foundations, organizations and individual donors. Please see our Thank You! and About Us pages for a list of donors and contributors.

The views and conclusions on this Web site are those of the authors and should not be interpreted as representing the opinions or policies of the California Fire Safe Council, the Santa Clara County FireSafe Council or the U.S. Government. Mention of trade names or commercial products does not constitute an endorsement by the California Fire Safe Council, the Santa Clara County FireSafe Council or the U.S. Government.