Steps being taken to isolate Sudden Oak Death

Sudden Oak Death was the name given to a new disease that was identified in 1995 and seemed to kill tanoaks and coast live oaks suddenly, within a matter of weeks. The cause of the disease has since been traced to a new Phytopthera species, a fungus in the same group as that which caused the Irish potato famine.

While our understanding of sudden oak death remains limited, there is great concern due to the potential of a disease like this to change whole ecosystems. An example often cited is the loss of the American chestnut, a tree that once dominated the forests in the eastern part of the country. In some areas of Marin County, where sudden oak death was first observed, 90% of susceptible trees are infected.

Until recently, infected trees were found only within 30 miles of the coast. A recent discovery of diseased trees in a drier area has raised fears about its ability to move inland. The loss of huge numbers of oaks from the California landscape would have far-reaching effects on plant and animal communities as well as the aesthetics of California.

In April of this year, the Director of CDF declared and the California Board of Forestry and Fire Protection approved a ³Zone of Infestation² which included seven counties: Marin, Monterey, Napa, San Mateo, Santa Clara, Santa Cruz and Sonoma. In July, the county of Mendocino was added to the Zone of Infestation. The California Department of Food and Agriculture initiated regulations in these same counties that restricts the movement of wood, mulch, dried or preserved wreaths, bark chips, or any other product that has not been processed.

These actions help increase public awareness of the problem and may make resources available for tree removal which is important because of the fire danger associated with large numbers of dead trees.

Currently, CDF and the California Oak Mortality Task Force recommends the following common-sense actions to avoid the spread of Sudden Oak Death into uninfested counties:

• Do not collect and transport plant material from infested plants (see list above).
• Do not transport soil or firewood.
• Avoid driving or parking vehicles in areas where they may become contaminated with soil or mud.
• Avoid damp soil or mud when hiking, biking, or horseback riding in infected areas
• Before returning to an area that is free of the disease, do the best you can to remove or wash off accumulations of soil and mud from shoes, mountain bikes, pet¹s feet, vehicles, etc.

For more information on this issue, consult the California Oak Mortality Task Force website at http://www.suddenoakdeath.org. This website contains information on the disease, its symptoms, treatment, current research, and other news. In addition, there is a mapping project that is collecting the locations of diseased trees throughout the state.