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Potatoes play an important role in the economy of Prince Edward Island (PEI), one of Canada’s east coast maritime provinces. Affectionately known in Canada as “Spud Island” potatoes feature prominently on the province’s post cards, guides on harbour cruises happily point out the berths from which seed potatoes are exported and, most surprisingly, taxi drivers in the capital, Charlottetown, seem comfortable discussing the current season’s problems with potato virus Y! Potatoes represent 50% of the province’s agricultural output and PEI was for many years the supplier of high quality seed potatoes to other Canadian provinces and neighbouring states in the USA. PEI, therefore, was a natural location for a summer study visit by a group of 12 members of the Scottish Pre-Basic Seed Potato Growers’ Association. The aim of the visit was to look at current seed potato production practices in PEI, to discuss variety breeding programmes and to see how increasing ware potato production had influenced seed potato disease patterns.
In the recent past more than 90% of PEI’s potato production was of early generation, high grade seed, with the bulk of production shipped off the island, but in the last few years this figure has fallen to around 25% due to transport costs and competition from other producers, and growers have seen better returns from growing ware potatoes. In 2007 approx 300 PEI seed growers entered 8,000 hectares for seed inspection. With the recent switch in the balance of potato production from seed to ware the province experienced an increase in seed-borne viruses and significant numbers of seed stocks failed to meet the certification standard of 3% maximum tuber-borne virus. In an attempt to protect the seed industry a provincial law was introduced requiring all potatoes planted to be of Foundation Class seed or higher and to meet the 3% tolerance for virus in a compulsory post harvest test on 200 tubers. This means that, in contrast to the UK, ware growers cannot save their own seed for future production unless it meets certification standards and has been post harvest tuber testing, actions that have brought the virus incidence back to manageable levels.
In the 1990s isolated outbreaks of potato wart disease (Synchytrium endobioticum) and potato ring rot (Clavibacter michiganensis ssp. sepedonicus) had a very serious negative effect on PEI’s seed production and the Canadian plant health authorities acted swiftly to bring both diseases under control. Fields in which potato wart disease was recorded were “scheduled” and taken out of seed production. Action against ring rot included a compulsory post harvest test on 400 tubers from each stock intended for planting, at a cost of approximately £120, and very strict control of seed movements in to and out of PEI. Each container of potatoes leaving PEI has to be disinfected against ring rot at an official or approved disinfection station and clearance certificates, allowing travel from the island, are not issued until this is done. Very occasionally the bacterium is detected at low levels in laboratory tests, most usually on the very limited amounts of seed coming in to PEI, but the disease has not been recorded in potato crops for many years and the province is considered to be effectively free from ring rot.
These intensive post harvest tuber testing programmes are undertaken at private testing laboratories licensed and strictly supervised by the Canadian Food Inspection Agency (CFIA) which has its national potato laboratory in Charlottetown. Interestingly, PEI’s private licensed laboratories are also approved to conduct tests to meet the plant health requirements of importing countries, though where a “quarantine” organism such as C. michiganensis or potato spindle tuber viroid is found confirmation by CFIA is required. CFIA conducts regular ring tests on analysts in the private laboratories, undertakes surveys of Canadian potato stocks for damaging diseases, has a full programme of research and development on test methodology and acts as the National Quarantine Station for potato material entering Canada. Potato Cyst Nematodes (Globodera spp) have never been recorded on potatoes in PEI but recent findings on neighbouring New Brunswick have resulted in a requirement for all Canadian seed potatoes intended for export to the USA to be tested.
As in the UK potato blight is an ever present problem and spray regimes are similar to those used in Scotland. Colorado Beetle control is achieved through seed bed applications of insecticide. Interestingly, most PEI seed is still cut prior to planting, a practice that raises the risk of spreading bacterial diseases. Haulm destruction is by mechanical topping, followed by spraying with ”Reglone”, and regrowth is prevented by mechanical root pruning, a practice that also reduces Rhizoctonia and aids tuber skin set.
PEI’s traditional seed industry has declined considerably in recent years, and there is a reliance on older varieties – Russet Burbank still accounts for 50% of PEI’s potatoes. With a Canadian preference for white fleshed table potatoes, rather than the yellow fleshed European types, there could be modest opportunities for new UK varieties and collaborative trialling programmes were proposed during our visit. The very positive action taken by the authorities to eliminate ring rot and to reduce virus levels in seed crops has restored the high health of PEI seed and may yet offer opportunities for an upturn in seed exports.
In addition to its attraction to those interested in potato production PEI is a beautiful province with fine coastal scenery, an attractive rural interior, some great sea food and a good sprinkling of celtic culture. Well worth a visit! I am grateful to the Society for assistance with travel costs.