Verticillium stripe continues to spread across the Prairies. Manitoba’s 2025 canola disease survey found the disease in 73% of the fields surveyed, and both Saskatchewan and Alberta keep reporting new detections each year. The trend is clear—verticillium stripe is moving fast, and it isn’t slowing down.
Verticillium longisporum is a soil-borne fungus that causes the plant disease verticillium stripe. It enters the plant roots and moves into the vascular tissue where it is carried up into the plant’s stem. Once into the stem, this is where the damage is caused as the pathogen spreads causing fragile stems leading to premature ripening and plant lodging.
Once verticillium gets into your field, it’s extremely hard to remove. The fungus produces microsclerotia, tiny black survival structures that can remain in soil for many years. The pathogen spreads mainly through soil movement: wind-blown soil, water, equipment, tires, footwear, or crop debris. Even a small amount of contaminated soil is enough to introduce the pathogen to a clean field.
The disease becomes even more damaging if blackleg is present in your fields. Unlike blackleg or sclerotinia—where resistant hybrids or fungicides can help—verticillium stripe still has no proven, targeted control tools. Warm, dry Prairie summers, which are becoming more common, create ideal conditions for disease development, meaning that even if your fields that haven’t shown symptoms before they are increasingly at risk.
Verticillium stripe appears late in the season, so the best time to scout is right before or after harvest. Key symptoms include:
- Stunted plants and early ripening
- Grey discolouration or starburst pattern in the root cross-section
- Unilateral striping on stems that darkens when rubbed
- Blackened tissue inside the stem when the outer layer is peeled back
- Small black microsclerotia forming under the plant stem epidermis
For now, managing verticillium stripe focuses on awareness and prevention. On your farm, practicing these broader integrated pest management tactics will help alleviate stressors from all plant diseases:
- Extend crop rotations to help reduce disease pressure over time by reducing inoculum amounts in the field
- Scout regularly; cutting stems open improves accuracy when distinguishing verticillium from other diseases. Verticillium is easily confused with other diseases, and thankfully other disease have a whole suite of management options such as blackleg.
- While no industry standard exists for verticillium stripe resistance ratings, hybrids demonstrating better tolerance do exist in the marketplace and it is best to talk to your seed provider to explore options.
- Harvest management; taking the crop off once it has hit physiological maturity, as the longer it is left the more damage verticillium stripe can cause.
- Keep soil where it belongs—limit movement between fields.
- Clean and sanitize equipment, especially when switching fields.
Continued research will be essential as we learn more about managing this pathogen long-term.
If you suspect verticillium stripe in your fields, the most reliable way to confirm it is by submitting samples to a commercial laboratory. A list of Canadian labs offering verticillium testing can be found here.
