The Santa Cruz Mountains are ground zero for Sudden Oak Death, which was first noticed in Santa Cruz and Marin in the mid-1990s and is believed to have been introduced through nursery plants. This plant disease has since spread throughout much of California’s coastal forests killing thousands of trees including tanoaks, coast live oaks, California black oaks and Shreve’s oaks. Last June, scientists revealed that the Santa Cruz Mountains contain the only known site where mature canyon live oaks are dying from Sudden Oak Death. Scientists previously thought that canyon live oaks were not seriously affected by the disease.
The Midpeninsula Regional Open Space District is a public agency managing over 58,000 acres in the Santa Cruz Mountains for environmental preservation and public enjoyment. While there is currently no known cure to Sudden Oak Death, the District is working with scientists researching several possible methods to treat and prevent its spread through forests.
The newest study uses the fungicide Agri-Fos in combination with the removal of adjacent California bay trees in an attempt to protect individual large oak trees. Bay trees are removed because they can host the pathogen that causes sudden oak death, Phytopthera ramorum, on their leaves, and spread spores to susceptible oak trees nearby. Agri-Fos is sprayed onto the tree’s trunks and may help protect healthy oaks by boosting their natural immunity.
This spring, twelve large canyon live oak trees in the Los Trancos Open Space Preserve will be sprayed with Agri-Fos for the second time. California bay trees within 16 feet of these oaks were removed at the time of the first spraying, in December, to reduce the risk of sudden oak death infection. Bay trees were also removed from around select large oaks in the Russian Ridge Open Space Preserve. Scientists will continue to spray selected oaks annually and monitor for Sudden Oak Death symptoms in this long-term study.
Oaks are not only beautiful; they play an important role in the ecosystem by providing food and habitat for wildlife and contribute to healthy watersheds. In 2005, the District committed more than $150,000 over 10 years to research the prevention and treatment of Sudden Oak Death. In addition to the new study at the Los Trancos and Russian Ridge Open Space Preserves, there are currently several other ongoing research projects on District land conducted in partnership with scientists from U.C. Davis, U.C. Berkeley, the U.S. Forest Service and Phystosphere Research.
By supporting research, the District hopes to help scientists develop the tools that land managers need to preserve a healthy natural environment, and provide safe, beautiful recreational areas today and for future generations.
For more information visit www.openspace.org/plans_projects/SOD or www.suddenoakdeath.org

Source: Kings Mountain ECHO April 2010