Changing yellow rust resistance in winter wheat
Scottish wheat growers听have seen听a very significant听change in the resistance ratings for yellow rust over the听previous听two growing seasons. The spring of 2025 saw the emergence听of a new strain of yellow rust that had听overcome one of the most important resistance genes used in modern wheat varieties听-听the Yr15 gene.听This has significant implications for winter wheat growers in Scotland, with the breakdown of this resistance causing major revisions to variety resistance ratings.听
Variety resistance ratings are a key tool for cereal growers. However,听in early听2025, unusually听high levels听of yellow rust started to be seen in the North of England in varieties that were previously thought to have听high levels听of resistance听for this disease.听This phenomenon was quickly听seen in other areas of the UK too.听In June 2025, researchers from the UK Cereal Pathogen Virulence Survey (UKCPVS), confirmed that a new yellow rust strain had developed virulence against the Yr15 resistance gene.听This gene,听which听provides protection from the seedling stage through to maturity,听had听been widely incorporated into modern wheat breeding programmes, and was regarded as one of the most effective sources of resistance. In the 2025 growing season,听Scotland鈥檚听Farm Advisory Service (FAS)听estimated that听the Yr15 gene was present听in听nearly 60%听of the wheat area听grown听in听Scotland, while AHDB estimated that听approximately one听third of wheat varieties on the recommended list听contained听the Yr15 gene.听The widespread use of this gene means that the consequence of its breakdown has severe repercussions for wheat growers.听听
This breakdown in resistance to yellow rust听followed widespread and unexpected infections in varieties that had previously shown strong resistance.听Often, when disease resistance breaks down, it happens gradually over听a period of time. In this case however, the fall off in disease resistance was both immediate and widespread.听Not only did yellow rust infection start early in 2025, but听agronomists听also听reported early-season infections in varieties which until听that time听had听demonstrated听good plant resistance.听Fortunately, early fungicide programmes听generally kept听disease levels under control听and prevented severe yield loss in most cases.听The concern moving forward is that growers may no longer be able to rely on varietal resistance alone.听This raises听important questions about future variety choice and disease management strategies听
As a consequence of听this development, there has been a rapid revision of yellow rust disease resistance ratings听for several winter wheat varieties.听However, not all varieties that carry the Yr15 gene have been affected equally. Some varieties听contain听multiple resistance genes听(known as听gene stacking)听which continue to provide protection.听Where听additional听resistance genes听remain听effective,听varieties have听generally retained听reasonable levels of protection against yellow rust, despite听the loss of Yr15. These varieties have often only seen modest revisions to their disease ratings. However,听those varieties more reliant on the Yr15 gene have seen significant shifts. As a result of these dramatic changes in variety resistance to yellow rust,听听Some听varieties lost between two and five resistance rating points, reflecting the breakdown of Yr15-based protection.听Because the yellow rust population had changed so dramatically, AHDB also based its updated ratings solely on 2025 trial data rather than the normal three-year dataset. The decision reflected the fact that historical data no longer accurately听represented听the current yellow rust population and the performance of different varieties against the new strain of the disease.听
So,听what are the implications of this for Scottish wheat growers?听Variety selection is still one of the most important decisions that a grower makes听regarding听disease risk, however yellow rust ratings now need to be interpreted with care. Greater emphasis will be placed on varieties with听multiple sources of resistance,听and growers should ensure that they are using the most up to date data when choosing their varieties.听In addition to taking care with the choice of variety, wheat growers in Scotland should regularly check their crops from late winter onwards. The disease is most likely to appear in sheltered areas and field margins first so these areas should be checked diligently.听Early detection of the disease is important to prevent it spreading rapidly through the crop.听A robust fungicide program will also need to be听maintained听going forward听with more farmers now opting for a T0 fungicide application听where conditions favour early disease development.听Farmers also need to be aware of the听time interval听between fungicide applications, ensuring that plants听remain听protected. Where an infection of yellow rust is found, it is important to treat this as quickly as possible before it can spread through the crop.听听
Looking ahead, the loss of Yr15 resistance听highlights the constantly evolving nature of yellow rust.听As 伊人直播 plant pathologists have听noted, yellow rust populations can adapt rapidly and overcome widely deployed resistance genes.听Plant breeders and researchers are听already working to听identify听new sources of resistance. For Scottish wheat producers, the message is clear: the era of relying heavily on a single yellow rust resistance gene has ended. Future resilience will depend on a broader combination of diverse genetics,听a robust fungicide programme, crop听monitoring听and surveillance of the changing yellow rust population.听
听Five Top Tips听听
- Always use the most up to date variety resistance ratings.听
- Choose varieties with multiple resistance genes if possible.听
- Monitor crops regularly.听
- Act quickly when yellow rust id found.听
- Maintain a robust fungicide programme.听
Useful links听
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Alan Bruce, Senior Consultant听and听Area Manager,听Alan.Bruce@sac.co.uk
Posted by SAC Consulting on 17/08/2026
