Samples used to monitor blight

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Published: June 18, 2014

TABER, Alta. — No potato or tomato grower wants to see late blight in their plants, but if they do, researchers would like a sample.

A piece of infected plant placed in a plastic bag, along with a moist paper towel, can be sent to any of five Alberta Agriculture or Agriculture Canada research centres in Lethbridge, Brooks, Stettler, Lacombe and Edmonton.

“I will take any type of sample,” said Agriculture Canada researcher Larry Kawchuk, who is based in Leth­bridge.

“The fresher it is, the better chance we have of isolating it and then being able to characterize it.”

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Agriculture Canada has been monitoring different strains of late blight for three years in efforts to identify them and track their occurrence, he said.

The fungal disease infected many potato crops in southern Alberta last year, preferring the wet and humid conditions of 2013. Late blight also infects tomatoes, and many gardeners saw the disease as well.

“Last year it was a much bigger problem than typically it is in Alberta,” said Alberta Agriculture plant pathologist Michael Harding.

“We had lots of fields and lots of home gardens with tomatoes that were devastated by late blight.”

There are numerous strains of blight and last year’s villain was US23, a strain that attacks tomatoes but can also infect potatoes. Infection produces sporangia, which can spread long distances on the wind and cause infection on susceptible plants where they land.

That means infected garden tomatoes and potatoes could also infect thousands of acres of commercial potato crops in southern Alberta.

Commercial, large-scale growers typically apply fungicide, but not so the casual gardener.

“If there are some tomato vines left over in a garden that are sitting on the surface or some potatoes that have been culled out or sitting in piles somewhere, and they were infected last year, they can be a host for the disease to start releasing those sporangia very early in the season,” Harding said.

Kawchuk said the US23 strain likely entered the region on tomato plants flown in from elsewhere.

About the author

Barb Glen

Barb Glen

Barb Glen is the livestock editor for The Western Producer and also manages the newsroom. She grew up in southern Alberta on a mixed-operation farm where her family raised cattle and produced grain.

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