Unusually early signs of yellow rust on several winter wheat varieties in Recommended Lists (RL) trials have prompted warnings for farmers to monitor crops more closely.
Recent inspections in RL trials across northern England have detected yellow rust on multiple varieties rated as resistant at the young plant stage in the latest 2025/26 RL.
This is according to levy organisation AHDB, which explains this includes some of the most widely grown winter wheat varieties.
Similar early indications are beginning to emerge in other trial regions, suggesting a broader pattern may be developing, it adds.
While it's not uncommon to detect new strains due to the highly diverse nature of the yellow rust pathogen, these early findings point to the possible emergence of a significant new strain—or strains—not previously seen in the UK.
Notably, some varieties historically rated as susceptible at the young plant stage are showing little to no signs of infection at affected trial sites, AHDB explains.
This could indicate a shift in the pathogen population, with new strains potentially displacing existing ones.
Mark Bollebakker, who manages the RL trials at AHDB, said: “The trials in question were at about growth stage 30 at the time of inspection, so adult plant resistance had not kicked in.
"When it does, from stem extension onwards, these varieties may outgrow initial infection. However, it is difficult to predict what will happen.
"We have sent samples to UKCPVS for testing to give us a better understanding of what we are seeing.”
Given the rapidly evolving situation, farmers are being advised by the levy organisation to check all varieties in the field before making final spray decisions and avoid relying solely on RL ratings until more information is available.
Trial inspectors are continuing to monitor developments, and further updates will be provided as soon as possible, AHDB concludes.
