Sub-zero temperatures in southern Alberta May 10-11 had growers worried about crops, but reports as of May 14 indicated only pockets of major damage.
Alberta Agriculture’s AgroClimatic Information Service recorded overnight lows of -5 C near Barons late last week, while Champion recorded -4, Rolling Hills and Etzikom -3.5 and Iron Springs -5.
The swath of potentially killing frost extended south of Vulcan to the U.S. border, concentrated mainly in the southwest.
A considerable amount of early seeded canola had already emerged, causing concern about damage to tender young plants.
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Troy Prosofsky, southern Alberta agronomy specialist for the Canola Council of Canada, scouted crops in the region May 14 and found a mixed bag of results, with some farmers already facing tough decisions.
“I would bet there’s going to be pockets where people are going to be reseeding,” said Prosofsy. “But it’s better than it could have been.”
He encouraged farmers in frost-affected areas to examine the canola cotyledons and look for pinching off. If it’s still green, the plant will likely survive although maturity could be delayed by one or two weeks.
Harry Brook of Alberta Agriculture said May 14 there might be isolated pockets of canola damage depending on how long the crop was subjected to frost.
“There’s been some damage done. It remains to be seen how severe. But there’s probably not a whole lot of reseeding to be done. That’s my best guess.”
A news release issued by the canola council earlier this week said temperatures of -8 C were recorded May 10-11, and that it would take a few days to gauge the health of the cotyledons. The plant is likely dead if no growth occurs within two or three days of frost.
As for reseeding, “if one or two plants per sq. foot have survived and if that stand is fairly consistent throughout the field, the best choice is probably to leave it alone,” said the council news release.
“A thin stand is not optimal for yield, but a thin stand in mid May may have better yield and quality potential than a reseeded field, particularly in southern Alberta.”
The council also advised that herbicide spraying can resume once good growing conditions return, which they did as of May 12, and if there’s no evidence of canola or weed damage.
“If there was heavy frost and plant tissue damage is greater than 40 percent of total leaf area, allow new leaves to grow before making herbicide applications,” the council news release said.
As for seeding progress in Alberta, Brook estimated 25 to 30 percent is complete, although progress is better in the south.
“I think psychologically, because we had very little winter and it’s been promising spring for months, people think it’s late,” Brook said.“But we’re basically back to just an average start.”
