Rotation is generally a critical part of mitigating any disease resistance problem.
When it comes to preventing the breakdown of resistance in blackleg-resistant canola varieties, the first line of defence is an extended crop rotation with non-host crops. Beyond that, growers can also rotate the canola varieties they’re growing, suggests Anastasia Kubinec, oilseed specialist with Manitoba Agriculture, Food and Rural Development.
In this Canola School episode, she notes problems with blackleg appear to be more prevalent in older “tried and true” varieties.
“We have had some excellent varieties grown in Manitoba and they’ve had really long longevity. They’ve been grown on many fields for five or six years,” explains Kubinec, noting this repeated use of the same variety has increased the chances of a breakdown in resistance.
Research conducted by Dr. Dilantha Fernando at the University of Manitoba determined the sources of resistance for some of the main varieties grown in Western Canada, but due to partner agreements for the project, this information has not been made available to the public. Without this insight on resistance genes, a grower can plant a different canola variety, but there’s no guarantee it will be less susceptible. However, newer varieties tend to have better resistance, says Kubinec.
“If they find that they’re all of a sudden seeing increased blackleg, they should think about switching to a newer variety or maybe a variety from a different company hoping that they have genes that provide resistance to the avirulence groups they have in the field,” she explains.
Fernando is also working with Gary Peng (AAFC/Saskatoon) and Ralph Lange (Alberta Innovates) to map the blackleg races present in Western Canada. With this information, growers could theoretically choose canola varieties with resistance genes that match the blackleg isolates present in their soils, a concept that has already been implemented in Australia (watch for more on blackleg resistance with Dr. Fernando in an upcoming Canola School.)