New hope in fight against ash dieback - a tree called Betty

A tree in Norfolk, nicknamed Betty, was predicted to show a very high tolerance to the disease

Ash dieback disease arrived in the UK in 2012 (Getty)

Scientists have made a “large first step” in efforts to tackle ash dieback by identifying the first UK tree with very high tolerance to the disease.

Chalara ash dieback, which could kill millions of ash trees, was first identified in the UK in 2012, and experts fear it could have the same devastating impact on the country's woodlands and landscape as Dutch elm disease did in the 1970s.

But a team of researchers from the UK, Denmark and Norway have identified genetic markers in ash trees that are tolerant to the disease, raising hopes of selective breeding to produce trees that are less susceptible to the ash dieback fungus.

Scientists assessed 182 ash trees in Denmark, which had been badly hit by Chalara, scoring them for visual signs of disease and then conducting a genetic analysis. They found three genetic markers in the trees that were associated with disease tolerance, and tested these on a separate group of Danish trees to see how well they predicted the trees' susceptible. They then screened trees in the UK to predict if they were likely to be mildly or strongly tolerant to ash dieback.

A tree nicknamed Betty, in a Norfolk Wildlife Trust woodland where there were a high number of infected trees, was predicted by the markers to show a very high tolerance to the disease. Betty is a mature tree that is currently healthy, despite being next to trees which are infected.

Initial screening of several small UK populations has also indicated that the markers for tolerance may be more common in UK ash trees, compared with other parts of Europe.

Professor Allan Downie, emeritus fellow at the John Innes Centre and coordinator of the Nornex consortium, which carried out the research, said: “The identification of genetic markers for trees with low susceptibility to ash dieback is a large first step, one of many that will be needed in the fight to help ash trees survive this disease epidemic.” He said it was “astonishing” the science had come so far in such a short time.

UK chief plant health officer Nicola Spence said: “This unprecedented work conducted by British scientists has uncovered an exciting development in tree health. It paves the way for tackling this destructive disease and will help ensure that Britain's stock of ash trees, and its countryside, remains resilient against pests and disease in the future.”

The research was funded by the Department for Environment, Food and Rural Affairs and the Biotechnology and Biological Sciences Research Council.

PA