2009 Plum Pox Survey Summary - Pennsylvania

Ten years have passed since the discovery of Plum Pox Virus in Pennsylvania in September of 1999 – ten years of intensive survey and eradication effort. We are pleased to report that no virus has been found in the past three years of survey, fulfilling the requirements necessary to declare eradication of plum pox virus from Pennsylvania. The Commonwealth will now move to a much less intensive monitoring phase in our survey program.

In 2009, joint USDA/PDA survey in the Commonwealth of Pennsylvania generated a total of 226,534 laboratory (ELISA) samples, with no PPV detections. This is the third year of all negative PPV data for the Commonwealth.

Samples collected included commercial orchard trees (209,841), residential property trees and shrubs (10,843), nursery and budwood source trees (5,732), sentinel and wild trees (118). The majority of these samples were collected in a 25-mile radius area that encompassed every part of the state in which positives had ever been found, but sampling did extend beyond that area to include commercial orchard samples from 10 counties as well as samples from PA nursery operations moved to adjoining states.

In addition to running all 226,534 samples in ELISA, a subset was tested using the more sensitive real time RT-PCR test. A total of 1,413 samples have been tested using this protocol, with no positive results.

No non-Prunus positives have been detected in the field, after extensive survey by Penn State University scientists, although non-Prunus has been successfully aphid-inoculated with Pennsylvania PPV isolates under experimental conditions (PSU/ARS research under appropriate containment).

This survey season marked the third year of all negative survey data in the Commonwealth. As of October 29, 2009, all PPV quarantine restrictions for commercial orchards and residential properties within Pennsylvania will have been removed. A limited nursery quarantine will remain in place during a 3-year monitoring phase of the plum pox program. The nursery quarantine does not affect the sale of Prunus from retail sites that buy-in their nursery stock, but propagation or long-term grow-out of Prunus is prohibited. This nursery quarantine provides further assurance to buyers of Pennsylvania nursery stock that the stock is safe to plant, that no hidden PPV infection will introduce the virus to new areas through the movement of infected nursery stock.

Total PA orchard acreage removed since the beginning of the program stands at 1,614 acres, unchanged from 2006.
After three years of all negative survey nationwide (2000-2002), the national survey (outside Pennsylvania) has focused on higher-risk areas of the country. In 2006, for the first time, this national survey detected positive trees in states other than Pennsylvania: 3 positive trees in New York and 1 in Michigan. In 2007 through 2009, both Pennsylvania and Michigan have conducted surveys that yielded all negative data. Positive trees have been found in New York each year since 2006. No link has been identified between Pennsylvania and the PPV finds in New York or Michigan.