Sudden Oak Death Situation

Sudden Oak Death Situation

Aerial photograph of tanoak mortality in Los Padres National Forest in Monterey County, CA.

Aerial photograph of tanoak mortality in Los Padres National Forest in Monterey County, CA.

Sudden Oak Death (SOD), caused by the fungus Phytophthora ramorum was first detected in California in 1995. Since that time the disease has spread to 14 counties and killed millions of oak trees, including species such as; tanoak, coastal live oak, California black oak, shreve oak and canyon live oak. It was also found to cause twig and foliar diseases in other plant species like California bay laurel, coastal redwood and Douglas fir. Infected rhododendron plants were identified in a nursery in 2001, but the industry wasn’t affected until several large west coast inadvertently shipped over a million potentially infected rhododendron and camellia plants all over the country. P. ramorum was then detected in 176 nurseries in 21 states. 

Change in species composition of forests and natural areas is a threat to ecological sustainability and stability brought on by the potential spread of this disease. The loss of so many oaks within a system could be devastating to wildlife, as a loss of food and habitat, could change fire frequency and intensity required by many tree species for regeneration, impede water quality and aid erosive forces through excessive exposure of bare soil. 

Canker on a coastal live oak caused by P. ramorum. Regulations have been put in place on unmanufactured wood  and wood products, including lumber, logs and firewood.

Canker on a coastal live oak caused by P. ramorum. Regulations have been put in place on unmanufactured wood and wood products, including lumber, logs and firewood.

Since 2001 California has been conducting annual aerial surveys for SOD. From these surveys they can detect and monitor tree mortality and forest damage. Data is compiled and used to complete sketch maps containing current year conifer and hardwood mortality, defoliation, and other damage. Recent data collected from aerial survey mapped dead tanoak using digital aerial sketch-mapping systems from approximately 1,500 feet above ground level.

Data are used to attempt to stem interstate spread, developing, implementing and promoting innovative management methods as well as prepare and employ rapid response plans for new wildland detections. Several federal, state and local agencies are involved in strategizing containment, monitoring and control of Sudden Oak Death and other pathogens that threaten natural, agricultural and economical resources including the U.S. Forest Service, Forest Health Protection Unit (http://www.fs.fed.us/foresthealth/), state agricultural agencies, and the USDA Animal and Plant Health Inspection Service (http://www.aphis.usda.gov/wps/portal/aphis/ourfocus/importexport?1dmy&urile=wcm%3apath%3a%2FAPHIS_Content_Library%2FSA_Our_Focus%2FSA_Plant_Health%2FSA_Domestic_Pests_And_Diseases).