State and Private Forestry

Sudden Oak Death

• Overview (follows)
• Publications and Related Links

Sudden Oak Death (SOD) is a forest disease caused by the fungus-like pathogen Phytophthora ramorum. This pathogen has caused widespread dieback of tanoak and several oak species in the central and northern coastal counties of California. It has also been found on numerous other species, including Douglas fir (Pseudotsuga menziesii), rhododendron (Rhododendron spp.), California bay laurel (Umbellularia californica), and camellia (Camellia spp.). At present, there are 38 species known to be susceptible to the Phytophthora ramorum. 22 of these have been recognized as regulated hosts by the United States Department of Agriculture, Animal and Plant Health Inspection Service - Plant Protection and Quarantine (USDA-APHIS-PPQ), and by the California Department of Food and Agriculture (CDFA). An additional 16 plant species are listed as associated with Phytophthora ramorum. These species are listed in full at: http://suddenoakdeath.org

In 2001 the USDA Forest Service and California State Polytechnic, San Luis Obispo developed a cooperative mapping and monitoring strategy to map and identify the fronts of infection and overall distribution of the phenomena called Sudden Oak Death. The strategy includes the following objectives:

• Conduct aerial surveys for the early detection of SOD and map hardwood mortality that visually appears to be related to SOD.
• Conduct ground surveys to sample hosts for presence of P. ramorum (labs also testing for P. pseudosyringae).

These surveys have been conducted statewide across known counties of infestation and border counties including the Sierra Nevada foothills annually since 2001. The following describes our progress to date (11/2003) for the 2003 program:

• Fixed wing flights initiated May 29, finishing July 9th, 2003
• Helicopter follow-up over select areas mapped from fixed wing
• Counties flown (all contain host types ranging from Moderately Low to Very High risk based on R. Meentemeyer, Sonoma State University.):
• Miles Flown (excluding helicopter flights): Approximately 10,000
• Number of polygons sketch mapped indicating fading and/or mortality of oaks and other species of interest: 425

Field Work:

Polygons are prioritized from the aerial surveys and helicopter flights for field visits that focus efforts on sampling for new infestation

• Approximately 100 sites visited on the ground
• One positive (Monterey, polygon 36 near Plaskett)
• 32 negatives
• 55 no sample taken (symptoms not found/other damage noted, access problems)
• at least 15 additional samples taken from suspect areas noticed outside aerial survey polygons, three pending with the rest negative

For interactive capabilities and detailed information on our database visit the oak mapper website at:
http://kellylab.berkeley.edu/SODmonitoring/OakMapper.htm

USDA Forest Service - State and Private Forestry
Last Modified: Friday, 01 October 2004 at 12:37:59 EDT