Unseen for a few years, two major wheat diseases have re-emerged, catching farmers off guard. Damon Smith, UW-Extension Plant Pathologist says he’s starting to see diseases really taking hold and shutting the plants down early.
“We’re seeing the resurgence of stripe rust and fusarium head blight (scab),” says Smith. “After several years of relative calm, this has caught many by surprise.”
Smith says he saw the most significant severity on certain susceptible varieties in our southern locations, particularly around Arlington. As we move north, the severity decreases. This aligns with the fact that stripe rust spores generally can’t overwinter in Wisconsin. Instead they travel from the deep south.
Fusarium head blight, another concerning disease, has also reappeared after a few years of dormancy. “It’s been about three years since we’ve had a significant scab event,” Smith explained. “This disease produces a toxin called vomitoxin. This can lead to dockages at grain elevators if levels exceed two parts per million.”
With fungicide application windows now closed, Smith recommends that farmers focus on scouting and preparing for the next planting season. “It’s too late to do anything preventative this season, but now is a great time to look at local variety trials and make varietal decisions for the 2025 crop based on disease resistance,” he advised.
He also emphasized the importance of combine setup to manage the impact of head scab. “Research from Ohio State suggests that adjusting the combine to increase the fan speed and open the shutter can help clean out damaged kernels, potentially lowering vomitoxin levels in the harvested crop.”
In addition to stripe rust and head scab, Smith mentioned other diseases of concern. “We’ve seen some powdery mildew on susceptible varieties, which is typically variety-dependent. We’ve also had reports of soil-borne cephalosporium stripe in the eastern part of the state, particularly in areas with tight wheat rotations.”
Looking ahead, Dr. Smith cautioned that the inoculum load from this year’s stripe rust epidemic could pose a threat next season. “We need to be more aware of stripe rust next year, especially if we have a winter with lots of snow cover that allows spores to overwinter.”