Instead of a blanket of yellow from fenceline to fenceline, canola fields this year look like they received a bad haircut – long in parts with plenty of bald patches.
The combination of newly emerging and flowering crops is causing farmers concern about sclerotinia stem rot, said canola specialist Phil Thomas.
“I’m getting lots of calls about it. If you have a good field, it’s still an issue,” said Thomas.
By the third week of July, most canola fields would have reached the 30 to 40 percent flowering stage, the time to check for sclerotinia.
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The fungus can lay dormant for up to seven years in the soil, but when it appears, it can cut yields by up to 50 percent.
Producers must decide if they need to spray a fungicide before symptoms appear, based on previous disease in the field and the upcoming weather forecast.
Sclerotinia is a disease more often associated with high management and heavier crops. Heavy, dense crops with a thick canopy are more susceptible to disease than lighter crops, said Thomas.
A new sclerotina-tolerant canola is expected to help farmers, but it’s not a complete protection against the tough disease, said Igor Falak, a research scientist with Pioneer Hi-Bred.
This spring about 130,000 acres of 45S51, the sclerotinia-tolerant canola, was grown across Western Canada. Falak has not received a progress report, but estimates dry weather conditions and frost may have reduced the amount of acres of 45S51.
Falak pointed out it doesn’t eliminate the disease in the field or offer complete tolerance.
“It reduces the amount of disease and infection on the plant. Sclerotinia is quite a powerful disease.”
Pioneer Hi-Bred’s variety information estimates it offers about a level five out of 10 resistance, acting as a tool in low risk areas or helping to manage the risk in combination with a fungicide.
A combination of spray and resistant canola works best.
Sclerotinia is a worldwide disease common to most broadleaf crops, including soybean, sunflower, peas, legumes, alfalfa and flax. Only crops like wheat and barley are not susceptible to the disease.
“There’s a significant number of hosts around to keep the disease alive,” said Falak. “It’s around to stay.”
Unlike other crops, canola has a fungicide approved to help fight the disease, but the fungicide is an imperfect tool, he said. Farmers must decide to spray based on the crop history and the weather forecast.
“It’s a tough decision for farmers to make.”
If yields are high, many farmers err on the side of using fungicide regardless of the canola crop. Having a plant tolerant to the disease offers farmers options.
“It’s a significant improvement that can help in managing the disease.”
Theoretically all canola is considered susceptible to the disease, but there are exceptions. Polish canola, with lower yield, is less susceptible than Argentine varieties. Crops in the 20 to 30 bushel range are less likely to get the disease.
A variety flowering a week ahead or behind a variety across the road may not get the disease just because of the timing of the weather and flowering.
Falak said it’s not just farmers struggling with the disease. Scientists also have difficulty finding solutions for the fungus.
Now that 45S51 is in the field, Falak said research would continue to find improved varieties with increased resistance.
“No doubt it’s moving the bar higher.”
