Canadian agriculture doesn’t import much from Australia, but the canola industry plans to adopt the Aussie approach to blackleg resistance ratings in the next year-and-a-half.
Instead of Canada’s present simple but misleading R and S ratings, the new system will break the R and S rating categories into families according to what genes offer resistance to what families of blackleg.
That better enables farmers to maintain blackleg resistance in their fields.
“There may be a few companies this summer that will be using the new labelling system, and moving into 2018 the majority of the companies will have been switched over to whatever the new system looks like,” said Justine Cornelsen of the Canola Council of Canada at Manitoba Ag Days Jan. 17.
“That will hopefully (lead to) better blackleg resistance and resistance stewardship within our fields.”
Blackleg is a growing problem for Canadian farmers because of China’s concerns and threats. Canada has promised to work hard to reduce blackleg incidence and im-prove management to keep China from adding restrictions to Canadian canola imports.
While the disease is not generally a massive injury to Canada’s production, loss of market access could and has cost Canadian farmers dearly.
The present resistance ranking system lists varieties as being resistant (R), moderately resistant (MR), moderately susceptible (MS) or susceptible (S) to blackleg but does not well explain how the resistance works.
Some growers believe an R means a variety is resistant to blackleg in general, rather than having resistance to specific strains of blackleg, but not others.
“I was shocked,” said Cornelsen, after finding multiple farmers not understanding how restricted the resistance is with some varieties.
Major gene resistance offers protection against only specific strains of blackleg, something that is shown in the Australian system.
Farmers can easily see what genes are packed into the variety they’re buying. It also serves as a reminder that farmers need to know what strain of blackleg exists in their fields. It also helps farmers plan a resistance rotation strategy, something few Canadian farmers presently do.
By rotating canola varieties among the different resistance types available, different types of blackleg are much less likely to adapt and overcome that resistance.
This is important, Cornelsen said, because early clubroot resistance was ruined by overuse of a few key genes.
“We don’t want to be having this happen in blackleg that severe,” said Cornelsen. “We want to move away from that as soon as possible.”
The exact nature of Canada’s new system is being decided in the next few weeks, she said.