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Potato crop specialist advises on how to pick the right seed potatoes

advises on how to pick the right seed potatoes


April 22, 2008
By Myron Love

Topics

When it costs up to $2,000 an acre
to grow and store potatoes, it pays to take the time to source your
seed potatoes carefully, noted potato crop specialist Robert Coffin.

coffin
Robert Coffin

When it costs up to $2,000 an acre to grow and store potatoes, it pays to take the time to source your seed potatoes carefully, noted potato crop specialist Robert Coffin.

“Making sure you have good quality seed is one of the most important elements in producing a good crop of potatoes, said Coffin, a part-time farmer, private potato breeder in Prince Edward Island and Saskatchewan, and an adjunct professor at the University of P.E.I.

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In his address at the recent 33rd Western Potato Council conference held in Brandon, Manitoba, Coffin urged his listeners to take the time to visit seed farms in the summer and their storage facilities in the winter. Study the inspection reports and post-harvest results and spell out their requirements in writing, he added. If a grower is buying through a broker, it is even more important to put the requirements in writing.

While seed potato operations may well be certified by the Canadian Food Inspection Agency (CFIA), Coffin noted that in itself doesn’t guarantee the potato seed is disease-free. The CFIA may have tested just a small part of the field, missing areas of disease. Or disease may have blown in from a neighbour’s field.

“I have seen an inspector decertify a field because the neighbouring field was diseased,” Coffin said.

Coffin also talked about potato viruses such as leaf roll and viruses Y, A and X (the latter is spread mechanically, he noted). The potential presence of viruses, he explained, is why post-harvest testing is important. Leaf Roll and viruses Y and A, which are spread by aphids, may not show up until the next season.

“Sometimes,” he said, “the plant has to grow to a certain size before the disease is apparent.”

In Prince Edward Island, he noted, post-harvest testing is compulsory. “We had a lot of aphids in P.E.I. in July,” he reported. “We have found a lot of virus Y is some seed lots.”

Coffin described bacterial ring rot as a very serious problem. It shows up as cracks in the potato skin through which a gooey liquid oozes out. It also provides an entry for other diseases.

“We have zero tolerance in Canada for ring rot,” he said.

He noted that the bacteria can survive for years in burlap bags, old potatoes and wood surfaces indoors. And even careful cleaning does not always eliminate the bacteria because it can clump and form a biofilm which prevents disinfectants from getting to all of the bacteria. Coffin compared the bacterial clumping to the plaque that dentists scrape off patients’ teeth.

“More research is urgently needed into bacterial ring rot,” Coffin
said.