Eradication, Containment, and/or Management Plum Pox Disease (Sharka)

NON-TECHNICAL SUMMARY: Plum pox disease or "Sharka" is the most economically important disease of stone fruit on a global basis. The disease is caused by the Plum pox virus(PPV) which has now spread through the remainder of Europe, the Mediterranean region and to several locations in the Western Hemisphere, including Pennsylvania and Ontario, Canada. Interstate and international cooperation is required to prevent the long-range movement of PPV in propagation material. National certification standards and educational activities are the objectives of this proposal.

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APPROACH: Project 3: The appearance of PPV in North America has created a need for the development of effective management strategies including the production of virus-free propagation material. In the event that PPV is successfully eradicated from the United States there must be safeguards against the possible reintroduction and spread of this disease. However, in the event that eradication is unsuccessful, disease management strategies must be developed to keep stonefruit production profitable. Project 4: The Plum Pox Virus is a recent introduction to North America. Because this is a new problem most people in the fruit industry from growers to scientists are not knowledgeable about the disease and good educational materials have not been readily available. A successful eradication program will rely heavily on the educational tools available to growers and the public. In the event that PPV becomes a management issue timely delivery of research results will be necessary for growers to make informed decisions. Since PPV is an issue that is important that there is wide spread participation in the development and implementation of educational programs. In order to reach a wide audience and make materials readily available traditional and novel delivery systems including grower meetings, extension publications, videos, and the worldwide web will be used. <P>

PROGRESS: 2001/10 TO 2006/09 <BR>
During the course of this project, 362 accessions that are potential hosts of Plum pox virus (PPV) were submitted for virus testing and virus elimination where necessary. The origin of this material represented numerous countries; 27% of the accessions originated in foreign countries. Countries that are known to have PPV (including the U.S.) were the source of 307 accessions. All accessions were tested by serological and molecular assays and by biological indexing to insure that they do not carry PPV. PPV was detected in an ornamental peach that originated from Romania. Presence of PPV was detected by woody indexing on the indicator Prunus tomentosa, by ELISA using the potyvirus group specific monoclonal antibody, and by RT-PCR. This confirmed the utility of P. tomentosa as a good indicator of PPV, and also provided some validation of the multi-layered testing strategies used to exclude PPV and other viruses from the U.S. fruit tree nursery and production system. All material that came in contact with the PPV-infected accession was destroyed. A proposal for a National Clean Plant Network was developed in an effort to insure continuity in the programs offering virus-testing of temperate fruit trees in an effort to discourage the use of undocumented and potentially virus-infected material. The proposed program differs substantially from existing programs by establishing regional distribution centers that more closely meet the demands of regional industries. Project personnel actively participated on committees associated with the North American Plant Protection Organization and the National Plant Board in efforts to establish standards for reducing risk of transporting pests in shipments of deciduous fruit trees.
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IMPACT: 2001/10 TO 2006/09 <BR>
The detection and subsequent destruction of a PPV-infected accession before it was introduced and propagated in the U.S. averted the need for expensive control measures. Efforts to contain the current PPV outbreak in Pennsylvania have cost in excess of $80 million; this does not include the losses to commerce by restricted international and domestic movement of fruit tree propagation material. Of the 361 clones that entered the program during the project, 40% were infected with viruses. Thus, these efforts successfully reduced the potential risk posed by PPV and other viruses to the profitability and sustainability of the nursery and fruit production industries of the U.S. Viruses of all fruit trees cost nurseries, producers and consumers $227.4 million a year.