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In 1995 the death of large numbers of tanoak trees was observed in Marin, Santa Cruz, and Monterey counties. In 1999 emergency funding for research was provided to investigate the cause of death of oaks and tanoaks in Marin County. In 2000, the cause of this infection was identified to be Phytophthora ramorum, a water mold commonly called Sudden Oak Death. This disease has spread to twelve coastal counties. Plants infected with P. ramorum have been observed in 12 counties along the west coast of California: Humboldt, Mendocino, Sonoma, Napa, Solano, Marin, Contra Costa, Alameda, San Mateo, Santa Clara, Santa Cruz, and Monterey. As of spring, 2003, there are 26 plant species
known to be susceptible to the disease. These species are infected
in one of two ways: in the trunk or in the leaves and twigs. The
species infected in their trunks often suffer lethal damage. These
include several species of oak trees. Plants Susceptible to Sudden Oak
Death Trunk Infection, Often Killed:
The species infected in their leaves and twigs usually do not die, but some may act as hosts that spread the disease by wind-borne raindrops. These plants may develop leaf spots and blotches. Plants Susceptible to Sudden Oak
Death Leaf/Twig Infection,
* recognized as a regulated host 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). As of spring, 2003, Sudden Oak Death has not been identified on Stanford University lands. In Grounds Services, we watch for problems in our oaks at Stanford, and have a monitoring program in place to keep records of select trees to record change in their health. We are also fortunate to have observant citizens report to us additional observations of possible problems with our prized trees. Alert to the potential devastation of Sudden Oak Death, we keep informed of results of recent studies by Bay Area leading scientists on oak health. In 2001, with several oaks on campus with health issues, we contacted
the Santa Clara County Agriculture Extension Services for help identifying
causes of symptoms. (Positive identification of Phytophthora
ramorum can only be made by certified samplers.) Samples of
tissue on the margin of live and dead infected tissue are cultured
by a laboratory. All samples taken at Stanford thus far have been
negative.
Visit our Horticultural Subjects archivePsyllid Infestation on Stanford
Campus Coincident Bloom: A Tool
for Pest Management at Stanford University |
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