Growers need to be aware of increased virulence in brown and yellow rust according to findings from the UK Cereal Pathogen Virulence Survey (UKCPVS) presented on Tuesday 26 February.

UKCPVS monitors how varietal resistance is affected by changes in the population of brown and yellow rust. Races of the rusts are classified as being virulent to specific cereal varieties or resistance genes found in the plant.

Dr Rosemary Bayles, Principal Cereal Pathologist at NIAB, who leads the project, explained: “Maintaining varietal resistance is a constant battle, the survey continues to find virulent rusts which arable farmers and plant breeders need to be aware of.”

The ‘Warrior race’ of yellow rust was first identified in 2011 on fifty per cent of isolates. In 2012, seventy-five per cent of isolates were virulent to Warrior showing the speed with which virulent strains become widespread in the population. More importantly, however, it has now been discovered that the Warrior race is virulent on adult plants of Claire and related varieties. One hundred per cent virulence for Robigus and Solstice, which was seen in previous years, continued in 2012.

For brown rust, 2012 also showed shifts in virulent races compared with previous years. Virulence for Robigus and related varieties was found in over fifty per cent of isolates. In Stigg, Warrior and Timber, virulence was identified in around forty per cent of isolates.

To get to grips with rusts, growers needn’t solely rely on fungicides. According to Dr Simon Oxley of HGCA: “Growers can plant a range of varieties on farm to reduce the risk of serious brown or yellow rust epidemics. HGCA Topic Sheets 119 (yellow rust) and 120 (brown rust) have diversification schemes which group varieties based on the likelihood of rust moving from one variety to another.”

Using seed production figures, Dr Bayles estimated the mix of varieties currently in fields across the UK. For brown rust, there is a concern that almost three-quarters of crops are from diversification group four. With yellow rust, the picture is more positive, a significant number of varieties from the highly resistant group one are being grown.

For more information about disease control, UKCPVS and copies of the presentations from the event visit hgca.com