The Kranich yellow rust race has been detected in the UK for the first time and winter wheat growers are being advised to inspect varieties closely as part of aUK-wide monitoring effort, says AHDB Cereals & Oilseeds.
The UK CerealPathogen Virulence Survey (UKCPVS) identified the new Kranich race from an isolate collected in 2014 and tested in the field in 2015.
The testing process revealed that some AHDB Recommended List (RL) and candidate varieties had a slight sensitivity to the new race.
No further Kranich isolates were collected in the UK in 2015 and the actual risk posed by the new race is unknown.
As a result of the latest development, growers are being asked to monitor all winter wheat varieties, including those with a high disease rating, and report abnormal amounts of yellow rust to the UKCPVS.
The UKCPVS will continue to monitor the situation and provide updates as soon as definitive information becomes available.
What is the Kranich race?
The Kranich race, which is named after a winter wheat variety, was first found in Denmark and Sweden in2011.
It is the first new race detected in the UK since 2011, which saw the Warrior race arrive and establish in the UK.
Yellow rust ace and year first detected in the UK
Recently, the European population of yellow rust has been replaced by new invasive strains, almost certainly originating in the Himalayan region. One group Warrior has come to dominate the UK population. It is too early to predict how Kranich will establish in the UK population but the UKCVPS will continue to monitor the situation.
Dr Sarah Holdgate,UKCPVS project manager based at NIAB, said: The Kranich race is believed to bean exotic incursion similar to the Warrior group of races, although the two are not closely related.
To establish its potential to cause yellow rust on UK wheat varieties, we inoculated AHDBRecommended List and candidate varieties with the Kranich isolate, at both the seedling and adult plant stages, in 2015.
Information on resistance at the adult plant stage is the most important.
In the adult plant inoculation trials in 2015, two newly recommended varieties Spyder and Graham showed a slight sensitivity to the Kranich race.
Based on adult plant disease data collected during 20132015, the disease rating, as published in the current edition of the RL, for both of these varieties is 8.
A rating of 8 is awarded when low levels of disease are observed in untreated RL trials.
From March,additional disease assessments will be conducted at some RL trial sites to strengthen monitoring efforts. Unusual disease findings will be shared with theUKCVPS and implications for control published on cereals.ahdb.org.uk/monitoring
Industry urged to send samples to UKCPVS
Dr Holdgate said:We need to work together to monitor pathogen populations. In fact, our success relies on infected wheat and barley leaf samples sent in from commercial crops and trials.
May, June andJuly is the peak period for sampling but we welcome rust and mildew samples at any time in the season from any variety.
Of course, we are especially interested in receiving samples from varieties noted as resistant to the disease observed.
Seedling stage resistance
Each year, AHDB also publishes UKCPVS information on winter wheat seedling stage resistance,for both established and newly recommended varieties.
The latest dataset, which is based on samples collected during 2015, is now available at cereals.ahdb.org.uk/ukcpvs
Irrespective of growth stage, if yellow rust symptoms are seen in crops, the advice is that growers should strongly consider applying a T0 spray to protect the crop from further yellow rust infection.