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A winter canola look-see

Looking at the feasibility of successfully producing this crop in eastern Ontario.

May 2, 2023  By Carolyn King

The Winchester plots provided a reminder that winter canola can bounce back from some overwintering stand reductions. In the spring when these photos were taken, plot 102 (planted Aug. 25) looked much better than plot 106 (planted Sept. 1), but their yields turned out to be pretty similar. Photos courtesy of Joshua Nasielski, University of Guelph.

Over the past few years, agronomy studies and producer experiences have been filling some information gaps and fine-tuning best practices for winter canola in Ontario. Much of that effort is focused on southwestern Ontario. 

But what about winter canola production in eastern Ontario? 

Canola and edible bean specialist Meghan Moran decided to start looking into what it might take to successfully produce winter canola in this region. With funding from the Ontario Canola Growers Association, she launched a two-year study at the Ontario Crops Research Centre – Winchester in eastern Ontario. 


Moran, who is with the Ontario Ministry of Agriculture, Food and Rural Affairs (OMAFRA), is collaborating on this project with Joshua Nasielski, an assistant professor at the University of Guelph. Moran is currently on parental leave, so for now the study is being guided by Nasielski and Ian De Schiffart, the University of Guelph agronomy technician at Winchester. 

“The goal of the study is an initial look to see if winter canola will survive in eastern Ontario and what the yields might be,” says Nasielski, who heads the University of Guelph’s Northern and Eastern Ontario Agronomy Research Group. 

Some eastern Ontario growers have tried winter canola, but it is not common in the region. “Part of what the Winchester research centre is there to do is to test new ideas and alternatives to see what happens and whether they are worth further exploration,” he says. The study also gives Nasielski and De Schiffart an opportunity to learn more about the ins and outs of winter canola production, a crop that is fairly new to both of them.

Nasielski notes that canola – whether it’s spring or winter canola – has some potential benefits for eastern Ontario crop rotations. 

For instance, growing canola could make winter wheat production more feasible. “Winter wheat is a challenging crop to fit into eastern Ontario rotations because of winterkill. However, it is much easier to get winter wheat planted early enough to survive the winter if you plant it after a spring canola or winter canola crop,” he says.

“Adding canola to a rotation would also have other benefits to the whole cropping system, like adding more diversity to the rotation and being able to change up your herbicides for resistance management.”

He notes, “Compared to spring canola, the primary advantage of winter canola in eastern Ontario would be higher yields.” 

Depending on the situation, winter canola may also have other possible advantages over spring canola. For instance, winter canola may have fewer problems with heat-stress damage to flowers and pods because it matures earlier in the season. It can also be more competitive against winter annual weeds and weeds that emerge in late spring. And it might reduce problems with certain insect pests, such as swede midge, because the plant has passed its vulnerable growth stage by the time the insect is at the right stage to attack.

The biggest risk for winter canola production is winterkill. 

“To overwinter, winter canola needs enough time to build out its root system and build up its reserves of carbohydrates and nutrients to survive overwinter,” says Nasielski. For overwintering survival, OMAFRA recommends that a winter canola plant should have at least six leaves and a tap root that is at least the size of a pencil before winter sets in. 

Research in southwestern Ontario by Eric Page with Agriculture and Agri-Food Canada has shown that winter canola needs to accumulate more than 600 growing degree days (GDD, base zero degrees Celsius) between its planting date and the first killing frost for good winter survival and maximized yield potential. 

“We talk about a growing degree day requirement as a shorthand for how much thermal time – growing time – the crop needs before its growth shuts down for the winter. Winter canola generally needs more growing time than winter wheat,” explains Nasielski. OMAFRA recommends planting winter canola about seven to 10 days earlier than winter wheat’s ideal planting date in a region.

He adds, “Farmers who grow winter wheat in eastern Ontario will do things like planting a slightly shorter maturity soybean so they can seed their winter wheat a little sooner. And they are very tactical about field selection, only growing the crop in fields with a history of good winter survival.” Similarly, he suggests that producers avoid planting winter canola in fields where winter wheat survival tends to be poor. OMAFRA recommends well-drained fields with low clay content for winter canola. 

Three planting dates, three hybrids
The study, which started in fall 2021, is assessing the effects of variety and planting date on winter survival and crop yields.

The fall 2021 planting dates compared in this study were: Aug. 25, Sept. 1 and Sept. 10. The 2022 dates were: Aug. 29, Sept. 6 and Sept. 12.

The winter canola varieties in the study are: Mercedes, a conventional hybrid and the only winter canola variety registered in Ontario; Inspiration, a conventional hybrid; and Plurax CL, a non-genetically modified Clearfield hybrid. 

The plots were planted after winter wheat. That is a common rotational choice for Ontario winter canola growers mainly because of winter wheat’s relatively early harvest timing. 

Before planting winter canola, the plots were sprayed with glyphosate to kill winter wheat volunteers and then tilled. No-till is not recommended for winter canola because crop residues increase the risk of serious slug damage to the young canola plants in the fall. 

Highlights from Year One
“For the first year of this project, we found we needed a planting date that would give the canola at least 700 GDD to have enough winter survival for a reasonable yield potential,” says Nasielski. “But this is just one year of data, so that’s very preliminary.”

In general, the yields were higher for the Aug. 25 plots than the Sept. 1 plots. None of the plots planted on Sept. 10 survived. 

The plants in the Aug. 25 plots had five to seven leaves before the first killing frost, while the Sept. 1 plots had three to five leaves.

“Another thing to keep in mind with winter canola is how much of a stand do you need in the spring to actually have a high yield potential? It seems you can get quite a bit of stand loss and still have reasonable yields,” he notes. 

“To those of us involved in the trial who didn’t have much experience with winter canola, some of the plots looked horrible after the winter. We’d look at a plot and think, ‘It’s a goner.’ But then it would bounce back and produce fairly good yields.”

Among the three hybrids, Mercedes had the highest average yields for both planting dates. For example, the average yields in pounds per acre for the Aug. 25 plots were: 2,988 for Mercedes; 2,863 for Inspiration; and 2,545 for Plurax CL. As a comparison, yield reports received by OMAFRA for Ontario winter canola harvested in summer 2022 were between 2,800 and 3,500 pounds per acre.

Once the results from the study’s second year are in, the findings should help to give a better idea of the feasibility of growing winter canola in eastern Ontario and help to provide better planting date information for the region. 


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