Canterra Seeds has tried to clarify claims about the clubroot resistance level of its CS2000 canola seed variety following questions from the Alberta Canola Producers Commission.
The seed company said Feb. 4 that its statement that the new variety has an “intermediate” level of reaction to the new 5x pathotype of clubroot may present a new term that growers don’t fully understand.
Canterra said the variety “is not a silver bullet” against clubroot and encouraged clubroot management practices, including rotation and equipment sanitation, in addition to careful variety selection.
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The response may not satisfy the commission.
“There’s no definition, that we know of, of intermediate resistance,” said general manager Ward Toma.
“The pathology subcommittee, the industry group under the recommending committee that works on this, has never said anything about various levels of resistance,” he said.
“Things have always been that it has resistance or it doesn’t. All of a sudden they’re talking about intermediate resistance.”
University of Alberta researcher Stephen Strelkov and the Western Canadian Canola/Rapeseed Recommending Committee’s pathology sub-committee say intermediate reaction is defined as severity of 30 to 69 percent.
A resistant variety would have less than 30 percent reaction and a susceptible variety would have more than 70 percent reaction.
Toma said the seed company’s claims of “revolutionary” resistance could convince some growers of a higher level of protection against clubroot than actually exists.
“Our concern is that there’s still spore buildup, potentially, if it’s not resistant,” he said.
“Resistance still allows spores to build up but at a lesser level, so our concern is that if you have a low level or intermediate, whatever that means, you have a yield hit and you’re still building up spore load.… You’re not really solving anything.”
Toma said the commission has written to the pathology subcommittee about the matter.
In its Feb. 4 statement, Canterra said CS2000, a Genuity Roundup Ready canola hybrid, had shown in independent testing to have an improved level of clubroot tolerance.
It said the variety is resistant to the 2, 3, 5, 6 and 8 pathotypes of clubroot, as well as intermediate resistance to the more recently identified 5x pathotype.
Strelkov said last month that a variety is considered resistant if severity is less than 30 percent of a highly susceptible check variety.
“(CS2000) wasn’t resistant in the sense that it still had a significant amount of disease, but the disease that it had was significantly lower than for a completely susceptible check,” Strelkov said.
Toma said canola growers welcome the breeding progress that the new variety represents.
“Up to this point, everything that was exposed to (5x clubroot) died, so this result offers evidence that strong resistance may yet be found,” he said in a Feb. 2 news release.
“Regardless of variety, best management practices for clubroot continue to be the application of sound rotation and sanitation in combination with genetic resistance.”
In a later interview, he put it this way: “We don’t want guys saying, ‘oh great, it’s resistant,’ and go back to business as normal. We need some clarity, we need some knowledge so we know exactly what we’re talking about here.”
barb.glen@producer.com
