August 6, 2003
From: EPPO Reporting Service 2003, No. 5 [edited]

2003/077 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, and at that time several actions were taken, mostly through the seed potato certification programme, to eradicate PSTVd from Canada. All nuclear stock seed potatoes were laboratory-tested and inspections of other stages followed in cases of suspected viroid infection.

As a result PSTVd has not been found in Canadian seed potatoes since 1980. No PSTVd has been detected in Prince Edward Island or New Brunswick since 1989, and it has been officially considered eradicated 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 provinces, 400 leaves were randomly collected from 201 and 225 fields of seed and ware 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 laboratory tests and the failure to detect the disease in field inspections for many years, Alberta, British Columbia, and Saskatchewan should be considered as PSTVd-free.

Additional surveys are ongoing in Nova Scotia, Ontario, Newfoundland, Manitoba, Quebec on seed and ware potatoes, in an effort to declare PSTVd officially eradicated from Canada. So far, PSTVd has not been detected. 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.

Source: 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.

[Eradication of any pathogen is an accomplishment. However, pathogens have a way of unexpectedly returning. The price of PSTVd freedom is vigilance on the part of quarantine agencies and sensible actions of those who are in the business of moving germ plasm around the world. - Mod.DH]