Saskatoon (Rural Roots Canada) – Verticillium stripe is becoming a growing concern for canola producers across Western Canada, but Bayer Technical Strategy Lead for Canola Tim Darragh says understanding how to identify and manage the disease can help growers reduce their risk.
Verticillium stripe is a soil-borne disease caused by the fungal pathogen Verticillium longisporum. The fungus infects canola through the roots and moves into the plant’s vascular system, restricting the movement of water and nutrients. The disease can lead to premature ripening, stunting, deterioration of stem tissue and yield loss.
Darragh says concern is understandable when a disease threatens one of the most important crops on many Prairie farms.
While Verticillium stripe is relatively new for many growers, Darragh says producers do have management options.
“We understand growers have concerns about Verticillium stripe. It is something new, and we want to make sure growers understand there are a number of different management options available. I think if we can talk through management and agronomy, we can help reduce some of that fear.”
Weather can influence disease development
Darragh says the rise of Verticillium stripe is driven by several factors, including increased levels of inoculum and favourable weather conditions that have helped the disease establish itself, particularly in Manitoba.
He says the shift toward more straight-cut canola acres may also be contributing, as Verticillium develops later in the plant’s life cycle and increases spore production as the crop approaches harvest.
Changes in how canola is harvested may also be contributing to the disease’s rise.
Scouting before symptoms appear
One of the challenges with Verticillium is that infection occurs through the roots when the plant is young, before moving upward into the stem.
That means growers don’t necessarily have to wait for obvious external symptoms before looking for the disease.
Darragh recommends cutting stems toward the end of flowering to look for signs of infection.
“If we look at the stem cuttings at the end of flowering, for plants that are infected with verticillium, there’s a dark brown ring that’ll start appearing. That’s an indication that the verticillium is in that xylem or that water flow tissue.”
He says that can allow producers to identify verticillium in a field before symptoms become visible on the outside of the plant.
Harvest management can reduce losses
Once Verticillium has been identified, Darragh says attention needs to shift toward protecting the crop through harvest.
The disease can weaken stems, increasing the risk of stem snapping and lodging. Darragh says growers should therefore be proactive rather than waiting for conditions to deteriorate.
Swathing is one option.
“Swathing allows growers to proactively manage the crop by cutting and windrowing it prior to the risk of stem snapping becomes significant.”
Straight-cut growers also need to closely monitor affected fields.
Darragh says once canola reaches 10 percent moisture and conditions allow combining, producers may want to prioritize the affected field, even if that means moving away from harvesting wheat or other cereal crops.
The goal is to get the canola off before a weather event causes lodging and additional losses.
No silver bullet for verticillium
Darragh says growers understandably want to know whether a product is available that can simply control the disease.
“Is there a silver bullet coming? Is there something I can spray on it to manage it? Those are the big questions that we’re having.”
For now, however, Darragh says producers need to think of Verticillium as a longer-term management challenge rather than something with a quick solution.
“The agronomy is probably the solution we want to focus on going forward because it’s gonna be the most sustainable to allow growers to be successful in the future.”
That makes communication between producers and agronomists increasingly important as more is learned about the disease.
Darragh encourages growers to share what they are seeing in their fields rather than ignoring the problem.
“We don’t want to be burying the problem. We don’t want to have our head in the sand around it. We want to have those conversations, and so the thing I would say is that if you’re seeing verticillium on the farm, start having conversations, start talking with other growers about it because again it’s going to be that agronomy that’s going to lead to the long-term management.”
More information on the action farmers can take can be found on Bayer’s lifecycle management chart.
