The Canadian Food Inspection Agency (CFIA) has completed its 2008 plum pox virus (PPV) survey activities and there was a significant drop in the number of positive samples, despite a 35 per cent increase in the number of samples collected compared to 2007.
The CFIA has collected a little more than 750,000 samples from commercial orchards and residential properties. Only 131 samples tested positive this year compared to 261 samples found positive in 2007.
This year's survey has also detected a new strain of PPV (PPV-Rec) in three trees on a residential property within the PPV quarantine area in Niagara (Grimsby, Ontario). However, this new strain detection is not likely to affect the eradication of PPV in Canada.
Additional surveys in the area suggest PPV-Rec has not spread outside of that property and the detection is an isolated occurrence. The positive trees were plum rootstocks with grafted apricot, peach and plum branches. The trees were detected as part of the homeowner's survey activities.
CFIA will continue to monitor for the presence of PPV-Rec, a strain only recently discovered and only known to occur in Europe. At this time, very little is known about the biology of the strain. Preliminary research seems to indicate that it could be aphid transmissible however the specific host range of this strain still needs to be determined.
This is not the first time a new strain of PPV has been found. In 2002, a new strain (PPV-W) was discovered at a residence in Stoney Creek (Ontario). Survey activities were enhanced in the surrounding area and no further positives were detected. The infected tree was removed and the strain type was never detected again in Canada. This was considered an isolated incident with no impact on the eradication program. PPV was declared eradicated from Stoney Creek in 2008.
Since 2000, plum pox virus had been detected and regulated in seven areas in Ontario and Nova Scotia. After eight years of effective regulatory controls and eradication programs, it has been eradicated in six of the areas. The only area now remaining under quarantine is the larger Niagara quarantine area which consists of the Town of Grimsby, the Town of Lincoln, the City of St. Catharines, the Town of Niagara-on-the-Lake and designated sections of the City of Niagara Falls, Town of Pelham and City of Thorold.
Under IPPC Standards (e.g., ISPM No. 8), PPV is considered present (only in 1 area of Ontario) and is under eradication in Canada. For more information on PPV, please visit the CFIA website at www.inspection.gc.ca.