A prolonged July heat wave should not take too much of a toll on canola and other crops, but dryness is a mounting concern, say experts.
Heat blast can be a problem for canola. The crop doesn’t like it when daytime temperatures soar past 28 C and nighttime temperatures remain above 16 C, and that has been the case in many areas of the Prairies this month.
Clint Jurke, agronomy director with the Canola Council of Canada, said that is when seeds and pods can be aborted during the bud to mid-flowering stages of development.
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However, whatever damage was done during the heat spell can be undone in the weeks that follow if conditions turn milder.
“The canola crop is pretty plastic. It can bounce back, make more pods and more seeds and regain its yield,” he said.
Canola plants usually produce more than two times the amount of flowers that are required, so if it takes 1,000 pods for a 40 bushel yield, the plant will produce more than 2,000 flowers.
Those extra flowers can be used to produce pods to make up for the aborted pods.
“This crop has surprised us so many times,” said Jurke.
“It will rebound. I’m pretty confident.”
He noted that people used to say you couldn’t grow canola in southwestern Saskatchewan because it is too hot and dry, but that has been the highest yielding area of the province in recent years.
Jurke said the canola crop is in good shape.
“From what I’ve seen in my travels from Portage la Prairie to Lacombe, the crop actually is looking pretty good, fairly uniform and actually is looking fairly robust,” he said.
“I’m pretty happy with how it looks.”
Murray Hartman, oilseed specialist with Alberta Agriculture, said a lot of canola crops were at the vulnerable stage of development when the hot weather hit, so there is reason for some concern.
However, he is much more worried about the dry conditions in the southern Prairies than he is about the heat.
Rainfall this growing season has been 40 to 85 percent of the long-term average for the vast majority of Saskatchewan and Manitoba. Dryness has been flagged as a concern in crop reports in both of those provinces.
Hartman has looked at crop yield data from previous years, and all the big production losses associated with heat happen during drought years.
“It’s the combination together of the drought and the heat that’s bad for those 30 percent drops in yield,” he said.
“If we get the moisture, I don’t care too much about the heat.”
Hartman said canola tends to get singled out as the crop that is susceptible to heat blast, but other crops such as peas, barley and even wheat are also sensitive at the reproductive stage.
The damage is more visible on canola plants with the missing pods. Farmers won’t see the damage in their wheat crops until harvest, when they count the kernels in the wheat heads.
Hartman believes the heat has caused some yield destruction, but it will be mitigated in the northern half of the Prairies, where crops are late and the soil moisture allows them to tolerate the heat better.
There will likely be more heat damage in the eastern half of the Prairies where nighttime temperatures are higher.
“We tend to get higher yields in Alberta even at similar moisture, and that’s partly because we get cooler nights from being so close to the mountains,” he said.
Hartman said the hot and dry conditions are making it hard for producers to decide whether they should spend money on spraying their crops with fungicide.
