From: http://www.oda.state.or.us/plant/ppd/path/SOD/

Sudden oak death (SOD), a new disease, was first on tanoaks near Mill
Valley, CA, in 1995. Since that time, SOD has spread throughout Alameda,
Contra Costa, Humboldt, Marin, Mendocino, Monterey, Napa, Solano,
Sonoma, San Mateo, Santa Clara, and Santa Cruz counties. SOD has also
been found on rhododendrons, Pieris and viburnum in Europe. In the Fall
of 2001, SOD was found for the first time in Curry County, Oregon , near
the city of Brookings. In 2003, this disease was reported for the first
time in nurseries in California, Oregon, Washington, and British
Columbia.

SOD is caused by Phytophthora ramorum . This fungus-like organism
invades susceptible trees through the bark, killing portions of the
tree. This creates an ideal environment for insects and other fungi to
invade. Woody shrubs are invaded through the leaves or the bark. The
origin of P. ramorum is presently unknown.

he USDA,Animal and Plant Health Inspection Service (APHIS) currently
recognizes 28 plant species as being natural hosts for P.ramorum and
thus subject to federal regulation. This pathogen has also reportedly
been isolated from several other plant species ("associated"hosts).
Associated hosts must go through a thorough scientific process before
being added to the official host list. To see the list, go to:

http://www.oda.state.or.us/plant/ppd/path/SOD/
or
http://www.aphis.usda.gov/ppq/ispm/sod/

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