Canola growers need a better decision-making tool for whether to spray a fungicide because the current system isn’t exactly high tech.
Farmers now walk into a canola crop and if they come out with damp pant legs, it indicates a need to spray for sclerotinia.
“The wet pants test doesn’t sound very scientific to me,” said Keith Gabert, Canola Council of Canada agronomist in Alberta.
Gabert said canola growers need something more sophisticated because sclerotinia, a fungal disease, was a major issue in 2016.
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Historically, it’s been a problem in Manitoba, where frequent rains in June and July allow the disease to flourish. But last year it was problematic across the Prairies thanks to a summer of excessive rain.
“This (was) probably the highest year in 20 (years) for sclerotinia in Alberta, Manitoba and I would say parts of Saskatchewan as well,” said Gabert, who spoke at Ag Days in Brandon in January.
In Manitoba, a provincial disease survey found that 90 percent of tested canola fields had sclerotinia stem rot. Holly Derksen, Manitoba Agriculture field crop pathologist, said 15 to 20 percent of canola plants in infected fields had symptoms of sclerotinia.
Canola yields were still decent in 2016 because many farmers applied a fungicide, sometimes twice, to control the disease. Gabert is worried that the disease outbreak in 2016 will plague farmers in future growing seasons because the fungus overwinters in the soil for years.
“Sclerotinia will remain a really important issue for them to manage as they come back to those fields.”
However, producers need to know the risk of sclerotinia to manage the disease.
Growers could spray a preventive application of fungicide, regardless of conditions, but that comes with costs.
If a spray isn’t warranted, the disease may develop resistance to fungicides more rapidly. Also, there are years when spraying doesn’t make economic sense.
“The biggest risk is that it’s not free. It’s typically a $25 to $30 (per acre) investment in the crop,” Gabert said. “You really don’t know if you’re going to get the two or three bushels back (in higher yields).”
Canola growers in North Dakota have a decision-making tool for sclerotinia. North Dakota State University produces a risk map for the state and provides a risk calculator for individual farmers. The risk calculator is based on weather, but also on whether sclerotinia was in the previous canola crop, the last time canola was seeded in the field and other factors.
Gabert said the North Dakota model is useful but has limitations.
“Those (risk) maps are only part of the solution,” he said. “On a regional basis, they’re relatively effective at predicting sclerotinia risk…. But on a field-by-field basis it’s really difficult to predict what your risk of sclerotinia is.”
Rainy weather and a dense crop canopy increases disease risk but sclerotinia can’t develop if spores aren’t present. To answer that question, InnoTech Alberta is developing a sensor to detect sclerotinia spores in a canola crop.
“If I have a tool that tells me … there are no spores, game over. I stop. No preventive application,” Gabert said. “I can’t do that today. But it looks like I will be able to do that in the near future.”
Combining such technology with a regional forecast model to “put growers on alert” would be a huge step forward from the wet pants test, Gabert added.
“I’m not sure how accurate we will get, but there is only room for improvement.”
Derksen said she is thinking about a collaboration with North Dakota to bring a similar forecast model to Manitoba.
