Industry explores alternative labels for blackleg resistance

Concerns are increasing about how long blackleg resistant canola varieties will be able to protect farmers from surging disease pressure.

Blackleg can inflict serious economic damage on the industry, and it already costs Canadian growers millions of dollars each year.

There are also concerns that the disease can be used against the Canadian canola industry to deny market access, as China did earlier this year, saying it did not want to risk accidentally importing blackleg in shipments of Canadian canola.

While all sectors of the industry can agree with the need to preserve resistance, it’s difficult for growers who’ve had a resistant-rated variety fail to know which type of blackleg resistance no longer works in their fields and which may still be effective.

The labelling system for blackleg resistance displays only if a canola variety is R (resistant), MR (moderately resistant), MS (moderately susceptible), or S (susceptible).

“Right now, with the current labelling system that we have, there is no rotation at all because for growers it’s a crap shoot of whether they are incorporating a new type of resistance in their rotation or not. It’s just a guess, and not even an educated guess,” said Clint Jurke, agronomy director at the Canola Council of Canada.

The uncertainty on which blackleg resistance a grower should use has prompted calls for a labelling system that tracks the type of blackleg resistance a canola variety possesses, similar to what’s used in other rapeseed and canola-growing regions like France and Australia.

It now sounds like those calls will soon be answered

Jurke said the industry is developing scheme in which the type of blackleg resistant a canola variety has will be displayed on the label.

“There is now information in there as to what type of resistance, how it performs in different fields or different racial structures of the pathogen. So we’ve been engaged with the industry over the past few years to see if there is a new type of labelling system that we can come up with,” Jurke said.

In the Western Canada Canola/Rapeseed Recommending Committee meetings this winter, the CCC is expected to be involved in discussions on how the labelling system will work, including what type of resistance will be included on the labels.

It promises to be a formidable task because the relationship between resistance in the canola germplasm and the various racial structures of the blackleg pathogen is complex.

Stewart Brandt, manager of breeding operations at Bayer CropScience, said the industry should not adopt a labelling system that measures only the qualitative resistance in the germplasm.

“It would seem quite simple to just have major dominant resistance genes, or qualitative resistance, and just keep rotating them, and that would best serve the industry. But some of the concern that I have with that kind of approach is the quantitative resistance, that is typically a lot more durable,” Brandt said.

Quantitative resistance stems from a complex interaction between many genes in a variety’s germplasm, while qualitative resistance is often derived from a specific gene sequence, which can be relatively easy to identify with makers on the genome.

Brandt said if a blackleg resistance labelling plan doesn’t include quantitative resistance, seed companies will spend fewer resources trying to develop that type of resistance because it would have less economic incentive.

“Going to one system over versus the other; i.e. going to qualitative resistance and focusing on that — there would be very little incentive for the industry or for seed developers to continue with the quantitative resistance, which is largely in the background of most of the germplasm grown in Western Canada,” he said.

Australia has experienced more severe blackleg infestations than Canada. While much of the difference in the outbreaks can be accounted for by the harsh Canadian winter, it’s important to note there is a greater focus on rotating qualitative resistance in Australia.

“We need to understand the disease a little better. Why have our disease infestations not been as severe as Australia while we’ve been largely relying on quantitative resistance for a number of years?” Brandt said.

Jurke said the current proposal for the new labelling system looks to identify only the qualitative resistance genes.

However, the existing labelling system with R, MR, MS, and S will be retained because it takes into account both the qualitative and quantitative resistance.

Plus, Jurke said, a long-term goal for new blackleg resistant labelling is to also include the quantative resistance.

“Eventually, we’ll need to tease that out to come up with the quantitative,” Jurke said.

“Anything is better than what we have right now. I think the industry understands we are going to take this step by step and whatever the new labelling system that comes out it’s likely not going to be perfect and it’s going to evolve over time.”

Jurke said he believes most of the industry is ready to adopt new labels that denote the type of blackleg resistance a canola variety has.

“We haven’t really heard any dissent at all from any of the life science organizations. So it seems like everyone is ready, it’s just a matter of working out the details of what this new classification system looks like,” Jurke said.

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