Can you help us solve the wheat yellow rust puzzle?

The UK Cereal Pathogen Virulence Survey (UKCPVS) needs wheat leaf samples with unusual levels of rust.

The annual call for samples is more pertinent this year, following unexpected observations of yellow rust on many winter wheat varieties classified as resistant to the disease at the young plant stage.

Initial observations were made at a Recommended Lists (RL) trial site in the North of England, but unusual levels of yellow rust have now been seen at other RL sites.

There has clearly been a shift in the UK yellow rust pathogen population.

Unusual levels of the disease continue to be picked during stem extension by RL trial operators. At this stage, adult stage resistance should have started to kick in, which is what the main RL wheat yellow rust ratings (1–9 scale) are based on.

At present, we do not know how much this will impact adult stage resistance. We will continue to assess varieties to determine the full impact of the change.

The latest phase of the UKCVPS project, which got underway last month, specifically supports breeding for durable resistance to yellow rust and brown rust in winter wheat.

The project focuses on rusts because of the relatively high diversity and adaptability of these pathogen populations (compared to other foliar diseases of cereals).

To monitor UK rust populations effectively, UKCPVS needs samples from infected leaves taken from geographically diverse areas and various wheat varieties.  

Most samples are sent through in May, June and July (when rusts are highly active).

The service has already received samples from 19 recommended varieties (by 28 April 2025).

To put this in perspective, UKCPVS received samples from nine recommended varieties throughout 2024.

• Sample five to ten infected leaves (when rusts are highly active)
• Fold each leaf along its length so the upper surfaces press together
• Put the samples directly into a paper envelope (do not use polythene bags)
• Fill in a copy of the sampling sheet (the more information, the better)
• Send the samples to FREEPOST UKCPVS (as soon as possible)

When high sample numbers are received, the UKCPVS team prioritises those taken from varieties that are expected to be resistant, according to RL data, but show unusual levels of disease in the field.

UKCPVS extracts pathogens (isolates) from the samples and multiplies them for use in varietal screens and long-term storage.

If a sample produces a unique infection pattern in the screens, it indicates that a new strain may be present in the UK.

Infection pattern data can also help narrow down the specific resistance gene or genes that have been overcome, which is extremely valuable for plant breeders.