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Plum Pox Virus (PPV) - Context

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Plum pox virus (PPV) (also known as Sharka) was found in fruit trees in Ontario and Nova Scotia as a result of surveying done in 2000 by the Canadian Food Inspection Agency. This was the first known discovery of plum pox virus in Canada.

Plum pox virus is a serious plant disease infecting stone fruit species of the genus Prunus including peaches, nectarines, plums, apricots, almonds and ornamental varieties. PPV does not kill trees, but can drastically reduce yields. PPV is transmitted from infected trees by aphids or by grafting or budding. Plum pox virus does not affect human or animal health.

The strain of the virus found in Canada has been identified as Strain D. This strain does not affect cherries. The same strain of PPV was found in Prunus trees in Pennsylvania in October 1999. This Pennsylvania find was the first time PPV was found in North America. The finds in Canada are not known to be linked to the Pennsylvania finds.

CFIA also reported the discovery of a new strain of the virus. PPV-W was found in two trees located at one isolated homeowner property. All trees were ordered destroyed and intensive sampling around the infection site did not discover any other incidence of this new virus strain. It is now considered eradicated in Canada.

Ontario

The threshold level for full block removal in the Niagara Quarantine Area has been reduced as of April, 2002. Removal is mandatory for orchard varietal blocks in which PPV infection level is 6.5% or higher. Removal orders were issued by the end of the 2003 growing season to growers whose blocks were infected at a level higher than the threshold.

A voluntary full block removal option with compensation allows growers to remove blocks that have infection levels in the range of 3.0 to 6.49%. This will allow the removal of blocks with relatively high levels of infection from farms whose owners are planning to replant previously removed blocks. Affected growers have been notified and removal orders issued where desired by the grower.

Sampling intensity has been increased in the Niagara and other isolated Quarantine Areas in 2003 with a forecasted total of 430,000 samples. This is being done to overcome virus distribution and titre problems in infected trees and improve PPV detection. The sampling has been divided between the CFIA and Agricorp, an Ontario crown corporation.

In the Niagara area, trees in new blocks are being sampled using the 4 x 12 intensive method, while all positive blocks are sampled individually. Trees in blocks with no history of PPV infection continue to be sampled using the 4 x 12 hierarchical method. Epidemiological studies are being done to gain more information on possible (PPV) spread in infected areas. Research on host range, aphid vectoring and genetic structure of PPV in Canada is ongoing.

Orchards in the isolated quarantine areas of Fonthill, Stoney Creek, Vittoria and Cedar Springs are being sampled individually. Any orchard blocks in which PPV is detected is ordered to be removed.

Mother trees used to propagate new plants are being sampled individually.

British Columbia, Quebec and Nova Scotia

Surveys of commercial orchards and nurseries are continuing for a third year in the stone fruit growing areas of these provinces.