The California Department of Food and Agriculture (CDFA) has confirmed that Sudden Oak Death (SOD) has occurred in Trinity County, California. Phytophthora ramorum is the pathogen known to cause SOD.
SOD is a serious invasive, quarantine disease that is killing tanoak, coast live oak, California black oak, Shreve’s oak, and canyon live oak trees in California. Since its discovery in 2000, more than three million trees have died, making it the number-one cause of tree mortality in California coastal forests. More than 500,000 trees have died in the last year alone.
A five-acre area where California bay laurel and tanoak trees were infected has been identified. Ground surveys to delineate the actual extent of the infestation will not be conducted until spring 2014, when symptoms are most advantageous for surveying.
California bay laurels, and the leaves of the tanoak, support both the production and spread pathogen spore. Tanoaks can die from the infection once it spreads to the tree trunk. Trinity County is now the fifteenth county in California known to have SOD. As a regulated county, Trinity will be required to follow state and federal quarantine guidelines for the disease.