'Red 24' now established in UK wheat yellow rust population

Yellow rust is a major disease of winter wheat that can cause big yield losses
Yellow rust is a major disease of winter wheat that can cause big yield losses

The Red 24 group of isolates, known to play a key role in the unexpected disease levels in 2016, is now established in the UK wheat yellow rust population.

Red 24 is relatively damaging compared to other isolates, and its continued presence in the UK is "not welcome news" according Dr Sarah Holdgate, UKCPVS project manager based at the National Institute of Agricultural Botany (NIAB).

Red 24 was first known to be present in the UK in 2016, and the group probably played a key role in the unexpected disease levels and revision of disease ratings in that year.

Recent tests on yellow rust isolates present in crops in 2017 reveal Red 24 is now the most dominant group in the UK yellow rust population.

These findings were presented at the annual UK Cereal Pathogen Virulence Survey (UKCPVS) Stakeholder Event, which took place today (7 March) in Cambridgeshire.

Dr Holdgate said: “Autumn 2016 was quite dry, and cold snaps last spring seemed to have dampened the disease going into the summer. We’ve also only received two yellow rust samples so far this year, most likely due to the cold weather this winter.”

'Damaging'

In total, 114 wheat yellow rust samples were received by UKCPVS in 2017, this compares to 340 samples received in 2016.

Tests on the samples received during 2017 revealed the continued dominance of Red-group isolates.

Red 24 isolates were the most commonly found (36 per cent frequency), followed by Red 28 (29 per cent frequency) and Red 11 (14 per cent frequency).

Dr Holdgate continued: “Work is underway to establish if Red 24 isolates are outcompeting other isolates. It’s important to understand the make-up of the yellow rust population to understand the impact on varieties.

“For example, Red 24 is relatively damaging compared to other isolates and its continued presence in the UK is not welcome news.”

Progress in research looking to introduce durable yellow rust resistance in wheat crops was also outlined at the event today.