Absence of Potato spindle tuber pospiviroid in Canada
The Canadian Food Inspection Agency (CFIA) has recently informed the EPPO Secretariat about the status of Potato spindle tuber pospiviroid (PSTVd - EPPO A2 quarantine pest) in Canada.
There were occurrences of PSTVd in Canada in the 1950s. At that time, several actions were taken, mostly through the seed potato certification programme to eradicate PSTVd from Canada. This included in particular laboratory testing of all nuclear stock seed potatoes, and inspections of other stages followed by testing in case of suspicion. As a result, since 1980, PSTVd has never been found in Canadian seed potatoes.
In the Provinces of Prince Edward Island and New Brunswick, PSTVd has been considered officially eradicated since 1989, on the basis of regular surveys. More recently, surveys confirmed its absence from 3 other provinces: Alberta, British Columbia, and Saskatchewan (De Boer et al., 2002). In these 3 provinces, 400 leaves were randomly collected from 201 and 225 fields of seed potatoes respectively in 1999 and 2000. Composite samples of 100 leaves were tested (by dot-blot) for PSTVd and all results were negative. Considering the negative results obtained in the laboratory and the failure to detect the disease in field inspections for many years, it was felt that Alberta, British Columbia, and Saskatchewan should be considered as free from PSTVd.
Additional surveys are ongoing in other provinces (Nova Scotia, Ontario, Newfoundland, Manitoba, Québec) on seed and ware potatoes, in an effort to declare PSTVd officially eradicated from Canada. So far, all results obtained from these Provinces are negative. CFIA also pointed out that PSTVd has never been found on tomato in Canada.
The situation of PSTVd in Canada can be described as follows: Absent, reported in the 1950s but no longer found, ongoing surveys are being performed in view of an official declaration of eradication.
Canadian Food Inspection Agency, Plant Health Division, 2003-06-16.
De Boer, S.H.; Xu, H.; DeHaan, T.L. (2002) Potato spindle tuber viroid not found in western Canadian provinces.
Canadian Journal of Plant Pathology, 24: 372-375.