continued from page 7 ONTARIO GRAIN FARMER COVER STORY 8 to ten days away from a T3 fungicide application and the variety is susceptible to stripe rust, a fungicide should be applied as soon as possible.” However, she advises that if stripe rust incidence and severity is low, a tolerant variety is being grown and a T3 fungicide application is less than a week away, a fungicide application can wait until T3. In terms of fungicide choice, if winter wheat is beyond the swollen ‘head in boot’ stage, a fungicide containing strobilurin should not be applied (see detailed information on fungicide selection at the OMAFA Crop Protection Hub). Grain Farmers of Ontario is also developing a technical fact sheet on stripe rust, to be released this spring. SNOW MOULD: A TOUGHER FOE Snow mould encompasses several fungal pathogens that can damage or kill cereal crops after prolonged snow cover. Snow provides insulation for these species, allowing them to grow throughout the winter. The most-common moulds (snow moulds) are pink snow mold, Typhula rot (called gray or speckled snow mould) and Sclerotinia snow mold. This fungal group is difficult to manage because so few management options exist, and because these species are hardy and persistent. In fact, snow mould can survive in the soil for such long periods of time that crop rotation has no effect as a management tool. Early nitrogen applications will also not help plants overcome snow mould. “It’s a very difficult disease to manage because there’s not much that can be done in the spring after the damage is done,” Vermey says. “It may be severe for some farmers. Your stands could be so thin that you decide to replant.” As with stripe rust, it’s difficult to say what 2026 holds for snow mould severity, but Ontario farmers should anticipate problems. Tenuta notes that while temperatures have been extremely cold (which can slow the growth of snow mould), the snow cover in some areas may be enough to insulate the pathogen and allow it to grow, however slowly. “The earlier the snow and longer snowpack persists, the greater potential for favourable conditions,” he says. “A break such as some areas had in late December-early January was good, but the heavy snows in January are concerning.” Farmers in areas with early snow cover should scout fields early in the spring, as soon as the snow has melted. Follings urges producers to prioritize scouting fields that were planted early and had significant top growth prior to snow coverage. She underlines the importance of conducting a number of stand counts and plant health assessments throughout the entire field to get a broader perspective on the status quo. “Continue to monitor fields with this disease after snow melt because damp and cool weather is conducive to continued growth.” She says. Follings notes that in fields with severe infection, the growing point of wheat plants can be damaged, which will ultimately kill the plants. But if the growing point is intact, yield impact should be minimal. In scouting, Tenuta says signs of infection are a white, felty or sometimes slimy fungal mat on plants and bleaching or other unusual colouring in the leaves (plants not greening up like they are in other parts of the field). These signs fade as the spring sunlight gets stronger and the snow disappears. Damage is highly variable, ranging from a few dead leaves to the entire plant. The disease is generally located sporadically in the field, with patches of dead plants or thinned areas being common. Heavy snowfall may be conducive to stripe rust overwintering in some areas, particularly in fields where disease pressure was high in 2025. Photo: Marty Vermey
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