Situation of Phytophthora ramorum in USA
In USA, Phytophthora ramorum (EPPO Alert List) occurs in coastal evergreen forests of California and Oregon where it causes sudden oak death. It was also reported from various states in nurseries causing leaf necrosis and twig dieback on various ornamental species; trade of nursery plants being an obvious means of spreading the pathogen. In USA, P. ramorum is subject to containment and eradication measures.
Sudden oak death
In California, infestations in natural settings have been found in 14 central and northern coastal counties. The 14 regulated California counties are: Humboldt, Mendocino, Lake, Sonoma, Napa, Solano, Marin, Contra Costa, Alameda, San Francisco, San Mateo, Santa Clara, Santa Cruz, and Monterey. The disease is widespread in Marin, Sonoma, Santa Cruz and part of Monterey counties. In Oregon, the disease is limited to Curry county.
On a national basis and as of 2005-11-16, 3,790 nurseries have been inspected and 68,275 samples collected. This year, 99 positive sites have been reported in the following states: California (55 sites), Georgia (4), Louisiana (2), Oregon (20), South Carolina (1), Tennessee (1), Washington (16).
Plant disease caused by Phytophthora ramorum. A national strategic plant for USDA (2005-09-15). http://www.aphis.usda.gov/ppq/ispm/pramorum/pdf_files/usdaprstratplan.pdf
APHIS. Pest detection and management programs – Phytophthora ramorum. Program update 2005-11-16. http://www.aphis.usda.gov/ppq/ispm/pramorum/updates/update11-15-05.pdf
California oak mortality task force website