A new project funded by the Danish Planteafgiftsfonden is mapping the susceptibility of leading wheat and rye varieties to four serious fungal diseases: yellow rust, brown rust, fusarium head blight, and ergot. The goal is to provide Danish farmers with a more reliable basis for selecting varieties and to strengthen integrated pest management (IPM) strategies that minimise the use of fungicides.

The four diseases vary greatly in severity from year to year and between locations. Rust fungi can evolve quickly and spread long distances by wind, meaning that a variety resistant one year may become partially or fully susceptible the next.
Fusarium and ergot present a different challenge: both can produce toxic compounds (mycotoxins), particularly under humid conditions before, during, and after harvest.

To reliably assess the susceptibility of cereal varieties, it is essential to expose them to controlled and uniform infection pressure. The trials benefit from the extensive expertise in plant disease management that Aarhus University, Flakkebjerg, has developed over many years in laboratory, greenhouse, and field experiments.

The project, led by Professor Mogens Støvring Hovmøller from the Department of Agroecology at Aarhus University, began in 2025 and is initially planned to run for three years. The experimental setup is revised annually, and the team has just re-applied for funding for 2026.

An unexpected development in yellow rust

Even in its first year, the project has produced significant findings. In spring 2025, a new race of yellow rust with Yr15 virulence was detected. This mutation has overcome the previously highly effective Yr15 resistance, which until now has protected nearly half of the wheat area in Northern and Western Europe, including Denmark.

“The breakdown of this resistance is one of the most remarkable developments we’ve seen in more than 20 years,” says Professor Mogens Hovmøller.
“Our results show that eight of the most widely grown wheat varieties in Denmark and Sweden have suddenly lost all or part of their protection against yellow rust. This knowledge is crucial for farmers when selecting varieties for the coming season, it helps identify which are at risk and which are still expected to maintain effective resistance.”

To follow up, the researchers have conducted additional greenhouse trials to identify varieties that continue to show strong resistance.

More than just yellow rust

Beyond yellow rust, the project also focuses on brown rust in wheat, ergot in rye, and fusarium head blight in wheat. Both ergot and fusarium are particularly problematic because their severity is strongly influenced by weather, previous crops, and timing of infection, and because both can lead to toxin formation, which is undesirable in food and feed.

This year’s fusarium trials showed that two common infection methods produced nearly identical results, strengthening confidence in the testing procedures. In 2026, the team will continue developing and evaluating infection methods to assess ergot susceptibility in rye.

European collaboration and context

The project is closely linked to international research efforts that the AU Flakkebjerg team is involved in. Notably, it forms part of the EU project IPMorama, where researchers collaborate with national variety testing programs at around 80 experimental sites across Europe to monitor and test the spread of new races of yellow rust, brown rust, and stem rust.

“This collaboration means that we can not only describe what happens in Denmark, but also place our results in a broader European context,” Mogens Hovmøller explains.
“When new rust races emerge, they often spread quickly, so it’s vital that we can compare results across countries.”

Knowledge directly for farmers

The project’s findings complement the official variety testing of cereals coordinated by TystofteFonden. Results are continuously evaluated and shared in Denmark through SEGES, SortsInfo.dk, and professional meetings, ensuring that the Danish farmers and advisors can apply the knowledge directly in practice.

Already after the first project year, both advisors and farmers have gained a more reliable foundation for prioritising disease resistance in their variety choices.

“We’ve only been running for a year, but we’ve already delivered new knowledge that can make a real difference for many crop producers,” says Mogens Hovmøller.

More information

Read more about the trials and the project here:  Quantifying disease resistance in cereal varieties (Aarhus University)

Contact:
Professor Mogens Støvring Hovmøller
Department of Agroecology, Aarhus University
+45 8715 8129
+45 2228 3361
mogens.hovmoller@agro.au.dk