Phytophthora ramorum, the causative organism in sudden oak death (SOD) disease, was found and confirmed in Monrovia Nursery in Azusa, California (Los Angeles County) on March 8, 2004, from samples collected as part of the APHIS-Plant Protection and Quarantine (PPQ) SOD survey. California Department of Food and Agriculture's (CDFA) plant pathology laboratory confirmed P. ramorum, causal organism for SOD, on six varieties of camellia. Affected varieties were Kamasaka, Bette Sette, Mrs. Charles Cobb, Kramer Supreme, Shiro Chan, and Jean May.

In addition, presumptive positives have also been found in 12 other nurseries in southern California (in Los Angeles, San Diego, and Orange Counties). Testing to confirm the presence of P. ramorum in these additional nurseries should be completed during the week of March 16, 2004. Previously, SOD had only been detected in northern California and a portion of Curry County, Oregon.

The confirmed positive nursery is one of the nurseries owned by Monrovia Nurseries in Los Angeles County which is a 500 acre facility that specializes in camellias; approximately 40 acres are planted with camellias. This parent nursery has 7 other satellite nurseries throughout the United States and ships plants every year all over the United States. We are working with CDFA which quarantined the nursery on March 9, 2004. Under the current protocol for nurseries infected with SOD, all the plants linked to SOD syndrome in the nursery need to be destroyed. CDFA advises that Monrovia Nurseries estimates 200,000 plants will be lost and $4.3 million lost in sales for March.

The presence of P. ramorum was unexpected because this nursery is not in the regulated area of California and is not located near any source of known infection. The nursery is situated in a dry climate, whereas previous detections of the organism have been confined to areas with a wet environment. The disease appears to be present in this nursery in at least two different species-camellia and viburnum.

There are no current regulatory treatments that are efficacious for treating plants against this disease.

To summarize, this discovery is significant because the disease has been found in an area that is atypical for predicting the establishment of P. ramorum; it has been found in a large nursery that ships stock throughout the United States; and trace forwards will be very extensive. CDFA and PPQ will be receiving shipping records from Monrovia very soon, and will be in contact with State counterparts regarding next steps. PPQ convened an initial conference call with representatives from the National Plant Board this afternoon.

Further information on SOD, including a list of counties in California and Oregon currently regulated due to SOD, is available at http://www.aphis.usda.gov/ppq/ispm/pramorum/

Claude R. Knighten
Public Affairs Specialist -USDA/APHIS
Plant Protection and Quarantine