A new fungicide to protect canola seedlings from blackleg, a major yield-robbing disease, could be available as a seed treatment for the 2021 growing season.
It’s called Saltro and was developed by Syngenta.
“Syngenta anticipates registration in time to make it available for use in the 2021 growing season,” Sarah Osborne, company marketing operations manager, said in an email Oct. 8.
While Saltro-treated canola will potentially increase yields, especially compared to canola infected with blackleg, it will also reduce blackleg inoculum, reducing the risk to future canola crops, and help extend the life of blackleg-resistance genes used to protect canola against the disease, according to Syngenta and industry experts.
Why it matters: Blackleg, which can cut canola yields in half, is on the rise in Western Canada. While some canola varieties are resistant to the disease, that resistance is no longer working in some fields.
The United States Environmental Protection Agency registered Saltro Sept. 6, 2019 as a canola seed treatment to control seedborne and airborne blackleg caused by Leptosphaeria maculans, Osborne wrote.
Saltro is also registered in the U.S. to control sudden death syndrome, early-season septoria brown spot and plant parasitic nematodes in soybeans.
“I think this is going to be a great tool,” Ted Labun, Syngenta’s seedcare technical lead for Western Canada, said earlier this fall, during a presentation in Winnipeg on Saltro.
“It’s not a silver bullet,” he said later in an interview. “But it’s part of an integrated approach with blackleg.”
One Manitoba plant pathologist agrees. Dilantha Fernando, of the University of Manitoba, has been testing the fungicide along with graduate student Rasanie Padmathilake.
He says the product will benefit farmers.
“One of the key things we’ve learned with the research we’ve done is the early infection has a much greater impact on the yield,” Fernando said in an interview after making a presentation on Saltro. “So if that initial infection can be controlled or managed… that would be really good for the farmer.”
There are two main types of blackleg in Western Canada. L. maculans is the most virulent.
It’s also the strain that infects canola at the cotyledon to four-leaf stage.
The earlier canola is infected, the higher the potential yield loss. Infected plant stems are girdled by cankers, blocking water and nutrients from moving through the plant.
The disease also weakens the stem and sometimes plants fall over.
Research has shown Saltro seed-treated canola results in much less blackleg inoculum. That’s an important benefit, Fernando said.
“I think that’s the key to this type of product,” he said. “Where you are reducing the pathogen inoculum, you’re reducing the opportunity for the pathogen to break down the resistance genes and even though you may not see a huge increase in the yield you’re overall managing your field with reduced blackleg (inoculum), which would contribute to one of the trade issues that we have because one of the key trade issues is looking at reducing the inoculum as much as possible in Canadian fields.”
In March China stopped importing Canadian canola seed complaining it was contaminated with blackleg. China has raised similar concerns before.
“When it comes to discussions at the scientific level, and even the diplomatic level, I think the message that the Canadian side needs to take is that we have done our due diligence and this is another management tool for blackleg reduction that is going to be to our advantage as our customers see we are doing the right thing,” Fernando said.
Blackleg seed treatment is the “missing link,” in blackleg management, Canola Council of Canada agronomy specialist Justine Cornelsen, said in an interview.
Asked if Saltro, and another blackleg seed treatment expected from another company could be a game charger she replied: “Yes, because we don’t have anything right now. If that major gene within the variety is not effective (in preventing blackleg), you’ve got no baseline protection. So this is just another thing to pair with your strong major gene and a quantitive background to that variety and then have this protection at that cotyledon stage.”
The canola industry is going to have to figure out how best to use Saltro, she added. Should it be on all canola seed or only used on acres where blackleg resistance has broken down?
“It’s trying to find the perfect fit for it because ideally we want it to last,” Cornelsen said. “We want to keep the sustainability of it going in the future. We have research projects on that now.”
Saltro’s impact on canola yield is also being assessed. Some yield comparisons have been done with untreated Westar, an old variety with almost resistance to blackleg.
“We need to be testing on these labelled resistant varieties,” Cornelsen said.
“That’s what I would like to see tested because that’s what we’re seeing in the field landscape.”
Blackleg is a stubble-borne disease.
“The way we grow (canola) every second year… is actually targeting for peak spore release in blackleg,” she said. “It’s about 16 months later, which puts you at the spring of the next canola crop is when that old canola stubble is producing the most amount of spores. That’s probably why we’ve seen an increase (in disease) this last little bit.”
Planting canola only once every four years greatly reduces the potential for blackleg infection, Cornelsen said. But because farmers believe they can make more money growing canola, many push the rotation.
An Agriculture and Agri-Food Canada study showed “longer rotations paid off, in the end, but you don’t see that year in and year out,” she said.
Part of the reason is new varieties are higher yielding, masking the damage from blackleg.
The best way to manage blackleg is an integrated approach, Cornelsen added. That includes crop rotation, growing resistant varieties, and in future, treating canola seed with fungicides that control blackleg, she said.