Wheat brown rust watch list

Based on Recommended Lists (RL) trial results, the wheat brown rust watch list reveals varieties that performed out of line with their RL disease resistance rating at some sites. Use the list to help understand disease risk and focus in-season management.

• The UK brown rust population is diverse
• RL brown rust disease resistance ratings use a simple scale – from 1 (least resistant) to 9 (most resistant)
• The ratings are based on a three-year data set and reflect average (across trials/years) disease levels
• These averages can mask relatively poor varietal performance at some trial sites
• The brown rust watch list addresses this, as it indicates varieties that performed out of line with their RL disease rating in some trials
• Pay closer attention to these varieties in the field
• The watch list is updated shortly after the launch of the latest RL edition (online tables)
• Typically, the update occurs in January or February
• Currently, the watch list broadly agrees with the RL disease ratings – most varieties widely perform as expected from their RL rating
• It is important to monitor all varieties closely and report unusual disease levels to the UK Cereal Pathogen Virulence Survey (UKCPVS)

All varieties on the current RL (2024/25) have been classified as susceptible to brown rust at the young plant stage by UKCPVS. However, the screening identified a candidate variety (RGT Goldfinch) as having resistance at this stage.

Initially introduced for wheat yellow rust (2021), watch lists provide a way to flag unusual levels of specific diseases observed in some trials, compared with what the headline disease rating would otherwise suggest. This extra layer of information may provide a valuable early warning of a potential change in the UK’s race structure and help focus in-season management strategies. After two seasons, analysis showed that the approach worked well for yellow rust. As a result, the approach was widened to include brown rust (2023).

The watch list orders varieties based on disease levels in the three worst trials for each variety (for the specified trial year), with three categories used to describe their performance.

Highly resistant varieties (near the top of the table)

The variety was resistant against the rust races present in all trials. The resistance is most likely to be effective against both common and uncommon races. A standard monitoring and fungicide programme is appropriate.

Medium-resistant varieties (near the middle of the table)

The variety was moderately susceptible to one or more races present in some trials. Refer to the RL rating to indicate whether this susceptibility is likely to be common (medium RL rating) or rare (higher RL rating). Monitor these varieties frequently. Be prepared to increase use of rust-active fungicides in the programme.

Low-resistant varieties (near the bottom of the table)

The variety was highly susceptible to one or more races present in some trials. Refer to the main RL rating to indicate whether this susceptibility is likely to be common (low RL rating) or rare (medium–high RL rating). Monitor these varieties frequently. Be prepared to increase use of rust-active fungicides in the programme. Currently, no varieties are in the low-resistant category.

Close alignment between the RL disease resistance rating and the watch list category means a variety is most likely to perform as expected in all locations.

The above chart is for illustrative purposes only. The coloured variety dots indicate the approximate relationship between the watch list and the RL disease ratings.

The graphic is based on yellow rust (RL 2021/22).

• Variety order based on resistance at the three worst trials for each variety (one-year data set)
• The RL 2024/25 brown rust disease ratings are shown for comparison (based on a three-year data set).

While AHDB makes every effort to ensure data accuracy, it is impossible to eliminate all errors. Due to the restricted number of trials considered in the watch list, anomalous results will have a disproportionate effect on the yellow rust categorisations, compared with the effect on the main RL rating. For overall varietal risk, use the main RL rating.

Always consider all characteristics of a variety. Growing varieties with a range of ratings, rather than only those with a very high potential resistance, may help to slow down resistance breakdown of some varieties.