Prairie canola growers are considering whether swathing ahead of the frost expected by the end of this week will allow their crops time to cure before it arrives.
Environment Canada’s forecasts across much of the agricultural Prairies call for overnight lows below 0 C by Saturday or earlier.
The federal agency already has frost warnings in effect as of around 3:30 p.m. Monday for several crop-producing regions, including areas of western Manitoba from The Pas down through Neepawa, as well as areas of eastern Saskatchewan from Carrot River down through Esterhazy.
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Manitoba Co-operator weather expert Daniel Bezte, writing for the ag paper’s Sept. 16 issue, agreed there “appears to be a very strong chance that a large portion of agricultural Manitoba will see frost sometime over the next seven days.”
According to the Canola Council of Canada in an alert for growers Monday, the goal of swathing canola ahead of a potential frost is to get the seed to dry down to below 20 per cent moisture — by which point the risk of seed damage due to frost is “minimized.”
It’s not likely, however, that most canola growing regions will see three warm, dry days between today and the forecast frost. Swathed canola usually needs that much time to dry down to 20 per cent moisture.
Seed colour change
The council suggested Monday that if seed has matured to at least 15 or 20 per cent seed colour change on the main stem, and if seeds are firm all the way to the top, growers may be further ahead to swath now and hope for the best.
“The yield penalty from swathing this crop early will be relatively small,” the council wrote. “It may not dry down to below 20 per cent, but drying it down to 30 per cent will cause less frost damage than staying at 45-50 per cent — especially if the temperature gets down to minus 3 C or more.
“Swathing these crops today may help save the grade, and if the frost doesn’t materialize, growers won’t have sacrificed too much yield.”
However, the council added Monday, growers will want to leave their canola crop standing for now if seed colour change is less than 10 per cent, with lots of watery seed in upper pods and pods on branches.
“These really green fields likely won’t dry down enough to completely protect them anyway,” the council wrote. “By leaving these fields standing, growers could see higher yields if the forecast frost doesn’t materialize or isn’t severe.”
Growers are also asking whether moisture on the ground protects canola from frost, the council noted.
“It won’t hurt the crop, but as for a benefit, the short answer is ‘Not likely.’ It’s moisture on the crop — rain or heavy dew — that provides some protection from frost.”
That said, the council wrote Monday, lots of ground moisture should boost the chances of higher humidity and heavier dew.
