Sudden Oak Death is here - what can you do to keep it at bay?

 Sudden Oak Death (SOD) is a tree disease that is killing some of the oaks in Sonoma County. Unfortunately, we have it in Fountaingrove II open space. The disease is caused by the plant pathogen Phytophthora ramorum, a water-loving fungus-like organism that produces plentiful spores in moist, humid conditions which may then be spread through wind-driven rain, water, plant material, or human activity. The spores spread from neighboring plants, such as California bay laurel trees, and enter the oak tree’s vascular system through the bark or through pruning wounds. It kills the tree, although the tree may appear alive and healthy for up to 2 years, until suddenly, it turns brown and dies. It has no known cure.

The following plants are known hosts for Sudden Oak Death: bay laurel, big leaf maple, madrone, manzanita, coffeeberry, camellia, rhododendron, coast and canyon live oaks, redwood, Douglas-fir, black oak, red oak, California buckeye, toyon, lilac, viburnum and many more.  Here is a graphic on what to look for in infected Bay trees:

There are preventive measures that may protect trees.  The Publication "Protecting Trees from Sudden Oak Death Before Infection" provides helpful information regarding those treatments, which can include the use of systemic fungicide phosphonate.  

The OSMA is trying to keep abreast of the latest information available. If you’d like to learn more about SOD, visit: for more information and photos of infected plants.


Below is an oak with SOD located behind Parker Hill Drive.