The first UK case of a devastating crop disease in 60 years has sparked calls for scientists, farmers and conservation groups to work together to prevent its re-emergence.
Stem rust, a fungal disease of wheat and barley, was largely eradicated in western Europe during the mid-to-late 20th century.
However, isolated outbreaks have occurred in recent years, and the discovery of a single infected wheat plant in Suffolk in 2013 became the UK's first confirmed case for decades.
Now a new study led by Norwich-based scientists warns that East Anglia's wheat and barley crops could be under threat from a perfect storm of conditions which could favour stem rust resurgence – a lack of resistance in modern cereal varieties, climate change, and the increased presence of the disease's alternate host, the barberry shrub.
Dr Diane Saunders and Dr Brande Wulff from the John Innes Centre in Norwich led a global team of collaborators to carry out genetic tests which showed the UK strain belongs to the Digalu race of the fungus, which was responsible for a devastating outbreak of stem rust in Ethiopia in 2013, as well as smaller outbreaks in Sweden, Denmark, and Germany.
Further investigations carried out by Dr Jane Thomas at NIAB (The National Institute of Agricultural Botany) in Cambridge found that more than 80pc of UK wheat varieties tested are susceptible to this strain.
This lack of natural resistance to the infection threat is compounded by the increasing popularity of barberry, a hedgerow shrub which acts as an alternative host for the pathogen, says the report.
The shrub was largely removed across England up until the early 1900s, as farmers noticed that cereal crops grown adjacent to barberry bushes were at greater risk of stem rust. But in recent years barberry shrubs have been planted in efforts to conserve the barberry carpet moth, an endangered species.
Dr Saunders said a larger study is needed to map and sample barberry across the UK, working alongside conservation groups. 'Replanting barberry in woodlands, gardens and areas away from arable land would ensure we provide vital habitat for the endangered barberry carpet moth, whilst limiting its potential impact on enhancing rust pathogen diversity,' she said.
Mark Parsons of Butterfly Conservation said: 'We are very concerned about the potential risk from the possible re-establishment of stem rust in this country and the impact it could have on agriculture and the environment.
'The barberry carpet moth is an endangered species restricted to just a handful of sites in this country, it being reliant on common barberry for survival. We are, therefore, pleased to be working closely with the John Innes Centre both to minimize the potential risk from cereal rust, but also to enhance the populations of the barberry carpet, and therefore increase its chances of survival in this country.'
Climate changes during the last 25 years are also believed to be creating more 'increasingly conducive conditions' for fungal disease growth.
Paul Fenwick, cereal pathologist at Lincolnshire-based Limagrain UK and co-author of the study, said research could help seed breeders play their part in building resistance to stem rust into new crop varieties.
'The discovery of stem rust in Suffolk has so far been an isolated one-off occurrence in 2013; however, with global temperatures set to rise by another one or two degrees over the next century, stem rust could extend its geographic range,' he said. 'Therefore, there is the potential for stem rust to become an ever-increasing threat across Europe and so research, such as this, will help to underpin breeding for resistance in the future.'
The study, named 'Potential for re-emergence of wheat stem rust in the UK', published in Communications Biology, says: 'The re-initiation of resistance breeding and a review of the mass plantation of common barberry to preclude re-planting near arable land and thereby limit the ability of the pathogen to rapidly overcome any introduced resistance and/or climatic constraints to safeguard European cereals from a large-scale re-emergence of wheat stem rust.'
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