Wheat growers warned of new ‘high input’ group of varieties

Latest Agrii trials have shown marked drops in yellow rust resistance scores for some of the UK’s most popular winter wheats, rendering some popular varieties as high input wheats.

The results follow identification of a new strain of yellow rust experienced across the country in 2025, with nearly 75% of varieties showing a fall in resistance averaging 2.0 points across the 31 varieties assessed across 14 sites, says Agrii seed technical manager John Miles.

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“The reductions are widespread, with some of the highest yielding varieties growers have come to rely on being the most affected.”

“Growers need to keep these and other results in perspective if they are still choosing varieties for next year, but equally the severity of the changes should be appreciated this autumn to avoid significant challenges next spring.

“We’re seeing some scores that were 9.0 last year, the highest in our ratings, drop to 3.0 and less.

“And while that sounds drastic, we’re urging all growers to look at varieties in the round and balance yellow rust susceptibility with other key traits.”

He points out that while for many farmers yellow rust was a non-event this year, “next spring could be more challenging.

“The new yellow rust race could affect the whole UK in 2026, and we all need to remain vigilant.”

Some of the most vulnerable varieties appear to be established names that previously had the highest level of resistance to yellow rust, he points out.

“Group 4 seems to have been the hardest hit (see table), with five varieties above 8.0 in 2024 falling to as low as 2.1 in 2025.

“Popular high-yielding hard wheat varieties like Typhoon have gone from a 9.0 in 2024 to 3.5 in 2025, for example.

“Dawsum slipped from a 9.0 to 3.9, Beowulf from 7.7 to 3.1, and Champion from 8.1 to 2.1.

“Of the soft wheats, Tapestry and Blackstone have suffered the most, going from a 9.0 to a 4.7 and 8.4 to 3.5 respectively and while Group 2 has fared generally well, with an average fall in score of around 1.4, Mayflower has gone from 9.0 to 4.8.

“In Group 1, new addition Vibe has been largely unaffected, going from 8.6 to 7.9 while Cheer has fallen from 9.0 to 5.7.”

Three groups

Agrii sees varieties falling into three “pots” and urges farmers to evaluate risk and management based on these.

John explains: “Pot 1 has succumbed to yellow rust. In the wider scheme of things they still offer much, but they have lost their full immunity.

“Pot 2 varieties were immune, but are quite badly affected, dropping to a medium level of resistance.

“This middle group captures some big varieties like Dawsum and Typhoon which still have real value, either because of septoria resistance, as with Typhoon, or the tried and tested performance demonstrated by Dawsum.

“Pot 3 is the new high input group. These may still have some really positive traits or the highest yield, but need considerable care. “We can think of these as the new Oakleys.”

The Agrii scores do tend to identify the “worst case” scenarios by their calculation method, John stresses, but this in turn identifies which are the most susceptible varieties.

“Our scores are based only on those sites where we have seen the problem. So if we have 10 sites and only five show yellow rust, the average will be based on those five, not the whole 10,” he explains.

“We believe this approach gives a better indication of varietal resistance when significant levels of pathogen are present. Just because a pathogen is not in one area in one year, does not mean it will not be there the next.

He explains that if a new race is seen across a good number of sites, and considering rust is wind blown, it could potentially reach the whole UK the next season.

Spring strategy

Looking ahead to next spring, John advises growers to talk to their agronomist and build strategic yellow rust control into their fungicide strategies when planning for next year, especially if they are growing one of the popular varieties that have suffered the most this year.

“We still have tebuconazole and strobilurins which are well priced, but they are not persistent and spray intervals can be small if pressure is high.”

Therefore, all growers should remain vigilant next year, especially as the exact nature of the new strain of yellow rust and its effect on all varieties in the future is still largely unknown.

“We need to focus on regional risk for yellow rust and be mindful of basics such as sprayer capacity, timeliness and quality of applications to ensure control is as effective as possible.

“‘Prepare for the worst, hope for the best’ is perhaps the best summary,” he says.

“Agrii will continue monitoring the situation on an ongoing basis and bringing as much science-backed data as we can to help advisors and growers.

“We will also continue our ‘tussock’ trials across 16 UK sites to evaluate what races of yellow rust are prevalent across the years, the heritage varieties with most resistance, and how we can identify solutions for the future.”