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Yellow rust continues to be a key focus for the industry

Product Update
Yellow Rust

The UK Cereal Pathogen Virulence Survey monitor and advise on yellow rust, Syngenta attended their 2018 Stakeholder Event to find out more.  

The UKCPVS Stakeholder Event 2018 was keenly attended by members of the seed industry earlier this month. A range of topics were covered including UKCPVS reports of the season, an update on field pathogenomics and further information on cereal disease resistance. Matthew Bull, a member of our Technical Crop Expert team, commented on the day: 

Considering the many changes in yellow rust races that were recorded during 2016, yellow rust remained a key concern for UK growers in the 2017 season, despite levels being lower than those seen in the previous year. 114 samples of yellow rust were tested from across the UK, all of which were from the Red or Blue pathotypes, which shows a less diverse range than in 2016.

The red group dominated in 2017 and within the red group, Red 24 was most common. Red 24 was identified along with Blue 7 as being responsible for the severe outbreak in 2016. New yellow rust isolates were found in 2017 within the red group, including Red 30. The impact on the UK is yet to be understood but UKCPVS will continue to monitor this specific pathotype. 

Yellow rust strains vary in importance and the degree of damage they are likely to cause. Work has been conducted to identify when different yellow rust groups infect the crop. For example, Red 24 is typically more severe and is early to infect, whereas Pink, Green and Purple tend to infect in late Spring through to Summer. Winter wheat varieties have also shown different levels of susceptibility to the various yellow rust groupings. Combining knowledge of variety susceptibility with an understanding of key risk periods could form a powerful tool in managing varieties most effectively to achieve optimum yield.

Diane Saunders of the John Innes Centre then went on to discuss monitoring stem rust of wheat in the UK. Although not currently recognised as a major disease, it once was. Prevalence is now next to non-existent due to earlier maturing varieties, development of modern fungicides and the wide removal of the alternate host, the barberry bush. In 2013, one wheat plant was found in the UK with Stem Rust, which when tested, showed similarities to the Digalu race which has been recorded in Ethiopia, Germany, Denmark and Sweden.

Whilst this does not pose a major threat to the UK at the moment, if it were to become more prevalent, over 80% of the UK varieties would be susceptible.

The barberry bush serves as an alternative host for both yellow rust and stem rust of wheat and, although no longer that common, it does still grow in the UK and regularly suffers infection of rust. With increased planting due to carpet moth conservation, rust species should continue to be monitored.