Shake-up for Recommended Lists wheat rust ratings

AHDB has made changes to the Recommended Lists (RL) wheat rust ratings
AHDB has made changes to the Recommended Lists (RL) wheat rust ratings

AHDB’s online edition of the Recommended Lists for cereals and oilseeds 2021/22 will feature major changes to rust disease-resistance ratings.

It follows the development of a new rating calculation approach that better reflects the diverse and dynamic nature of the UK’s rust populations.

Catherine Harries, who works on the Recommended Lists (RL) disease ratings at AHDB, said the yellow rust population structure varied in time and space, right down to variation across a single leaf.

"With rust pathogen populations continually evolving and disease pressure increasing, we have recently encouraged closer crop inspections. This is the best way to assess in-season pressures," she added.

"However, it has become clear that we need to overhaul the rating’s process, in response to the new reality of tremendous rust diversity.”

During 2020, the RL board has consulted with agronomists and farmers to develop a new, more representative method to calculate brown and yellow rust ratings.

To complement the adult-stage yellow rust resistance ratings published in the RL, the UK Cereal Pathogen Virulence Survey (UKCPVS) determines young-plant resistance to yellow rust for recommended and candidate varieties in RL trials.

The latest results show no change in resistance in 2020, compared with 2019 – most remain susceptible.

However, a high number of candidates (13/17) are resistant at the young-plant stage.

Due for launch on 30 November, the latest developments will feature during AHDB’s Agronomy Week – a five-day series of online webinars and videos, covering contemporary agronomy – that starts on the same day.