More than 30 percent of canola plants in Alberta had blackleg in 2016. The number may seem high but a plant pathologist says the figure is correct.
“My feeling is that it’s accurate. When we look at fields, we have very little problem finding it,” said Ralph Lange of Alberta Innovates Technology Futures.
Lange, who spoke at the Canola Council of Canada’s Oct. 25-27 Canola Discovery Forum in Winnipeg, said Alberta canola growers shouldn’t panic over the incidence of blackleg, but it is a concern.
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“It’s the most common canola disease in Canada. It gets under-diagnosed, big time. (Plus) incidence means you get any sort of symptom on a plant. It could be minor.”
Blackleg is a fungal disease, also known as stem canker. It can cause substantial yield losses in susceptible varieties or when the fungus overcomes resistant genes in the canola plant.
Provincial government surveys have found that the incidence of blackleg was much higher in Alberta this summer than in other provinces:
- Alberta: 34 percent
- Sask: seven percent
- Manitoba: 12 percent
Justine Cornelson, a Canola Council of Canada agronomist for western Manitoba, said Alberta Agriculture surveyed 500 fields this year and found that 92 percent of them had blackleg. In the fields with blackleg, 34 percent of plants had the disease.
Based on those incidence numbers, which are estimates and won’t be finalized until this winter, 31.3 percent of canola plants in Alberta had blackleg this year.
In 2015, the incidence of blackleg in Alberta was 13 percent. Alberta Agriculture staff also evaluated the severity of blackleg infection, but that data wasn’t available at the Winnipeg conference.
There were canola fields with severe blackleg symptoms and extreme impacts on yield, but most canola fields with blackleg had minimal losses, Lange said.
“There are lots of fields where it might be present, but (the fields) are in pretty good shape,” he said.
“(In) most of the fields, resistance (to blackleg) still seems to be holding. Even if you get incidence and some pretty high incidences, severity stays low. So we’re not getting major disasters, but they do happen.”
Lange said 2016 was an ideal year for blackleg, thanks to wetter than usual growing conditions.
It’s difficult to compare 34 percent incidence because Alberta doesn’t consistently monitor blackleg. For instance, there is no data from 2013 and 2015 and most of the 2000s.
However, the trend line for the entire Prairies is up since 2010:
- Incidence levels in Manitoba were around five percent from 2001-09 and around one percent in Saskatchewan.
- Incidence levels have climbed to 15 to 20 percent in Manitoba and Alberta in the last five years.
- Saskatchewan incidence of blackleg is now seven to eight percent.
