On April 22, 2004, USDA’s Animal and Plant Health Inspection Service (APHIS) issued an order restricting the movement of nursery stock from California nurseries, amended from an order issued April 9, following extensive negotiations between federal and state plant protection officials.
In order to prevent the spreading of P. ramorum, or sudden oak death (SOD), APHIS established restrictions on the interstate movement of nursery stock that has been identified as a host or associated host from commercial nurseries in 46 non-quarantined counties in California until the nursery has been inspected and determined by USDA diagnostics to show no evidence of SOD infestation. The 10 counties currently under quarantine are Alameda, Marin, Mendocino, Monterey, Napa, San Mateo, Santa Clara, Santa Cruz, Solano and Sonoma. The amended order adds Contra Costa and Humboldt to the list of quarantined areas.
According to Claude Knighten, media contact for APHIS and the SOD hotline, there are two separate quarantines. APHIS is regulating hosts and associated hosts of P. ramorum from the 46 non-quarantined counties. From the 12 quarantined areas, APHIS is regulating other material, such as soil and wood items.
"We’re having dialogue with the states daily and with the national plant board," said Knighten. "We’re trying to safeguard the states because we understand how they feel, but at the same time, we want to allow free trade."
Hosts and associated articles inspected, tested and determined to be negative for SOD using both PCR and culture/morphological protocols prior to April 23, 2004 are eligible for interstate movement, provided that the nursery is operating under a compliance agreement with APHIS. All nursery stock and associated articles shipped interstate from California must be accompanied by appropriate federal certification issued under a compliance agreement.
Samples will be analyzed using a methodology at a laboratory approved by APHIS. APHIS uses ELISA prescreening of plant samples, nested PCR tests and culture tests to determine the presence of P. ramorum. According to APHIS, if ELISA prescreening is not performed, or if the results of ELISA prescreening are positive for SOD, plant samples must be analyzed using either the APHIS-approved nested PCR or culture test. Positive PCR tests do not require confirmatory culture tests, nor do positive cultures require confirmatory PCR tests. However, if cultures are negative, a nested PCR test must be conducted. No culture test is required if a PCR test returns negative.
According to the USDA, "Given that nurseries outside the quarantined area are not covered by the current regulations, we are implementing new restrictions on the interstate movement of host nursery stock and associated articles from all commercial nurseries in California that are outside the quarantined area. This action is necessary on an emergency basis to prevent the potential spread of P. ramorum to non-infested areas of the United States outside California."
According to the American Nursery and Landscape Association (ANLA) analysis of the USDA-APHIS order, the amended order ensures that all California nurseries shipping known SOD hosts and associated plants interstate are subject to inspection and diagnostic testing prior to shipment. It also places temporary holds on all hosts; associated plants; plants located within a 10-meter radius of hosts and associated plants; and all plants within host and associated plant genera, pending inspection and testing. The order establishes the parameters for testing, including which types of diagnostic tests APHIS will use and the response to either positive or negative test results.
According to the order, a minimum of 40 samples must be tested per nursery location. One sample may contain more than one leaf, but no more than one sample per plant can be taken. According to the USDA, "Samples will be taken from symptomatic plants unless no symptomatic plants are present. In that case, asymptomatic plants will be sampled. Sampling shall be biased to hosts, associated articles and nearby plants."
"Today’s action is not perfect, and the amended APHIS order will result in some short-term pain for both California growers and plant retailers across the country," said Craig Regelbrugge, senior director of government relations at ANLA. "Hopefully, as new measures are implemented over the next few days, the system will begin to return to normal. Yet, strong federal leadership is key, and USDA seems to be stepping up."
For further information regarding the testing protocols and amended order, visit www.aphis.usda.gov/ppq/ispm/sod/survey.html .