Breeding plants resistant to Ash dieback fungus is essential if the trees are to survive

Conservationists should breed trees resistant to ash dieback in order to save Britain from the killer fungus.

Ash dieback is in danger of wiping out the UK’s 125 million ash trees, but around one in 100 can fight off the epidemic.

They may have a genetic advantage, possibly causing their leaves to die early in autumn, so that the fungus cannot burrow into leaves and infect a tree.

A British scientist has now worked out that resistant trees could prevent millions of deaths.

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Conservationists should breed trees resistant to ash dieback in order to save Britain from the killer fungus (pictured) 

With the current level of resistance, which means about one in 100 ash trees survive the ash dieback virus, Professor Matthew Evans says 95 per cent of trees are likely to be wiped out by the end of the century.

But if one in 10 British trees were tolerant to ash dieback, the ash population could be cut to only a third of its current size.

Professor Evans, who created a computer model for tree deaths, concludes that enough resistant trees will not appear on their own.

Ash trees are pollinated by the wind, so pollen from a non-resistant tree can land on a resistant one, meaning its ‘helicopter’ seeds may not have the parent tree’s ability to ward off ash dieback.

This is why some experts support ‘selective breeding’ by taking cuttings or artificially pollinating resistant trees.

Professor Evans, from the University of Hong Kong, states: ‘As has been suggested by other authors, it seems reasonable that selective breeding could play a role in the conservation of ash forests.

‘The establishment of a source of resistant individuals that could be used to boost the numbers of naturally resistant trees in the population would help increase the chances of a population sustainability.’

Ash dieback came to the UK seven years ago from Europe, has no cure and leaves diamond-shaped scars on bark. Causing leaves to fall off trees, it can decimate 60 per cent of trees in woodlands.

Ash dieback is in danger of wiping out the UK’s 125 million ash trees, but around one in 100 can fight off the epidemic. This image shows and infected tree

A British scientist has now worked out that resistant trees could prevent millions of deaths. This image shows a closeup of the fungus

The new study suggests that the fungus could make ash, now one of Britain’s most common trees, more rare than oaks, sycamores, hazel and hawthorn trees.

The computer model, which was created based on Wytham Woods in Oxfordshire, shows a worrying vision of what would happen if ash dieback became established in the UK over the next decade.

Numbers will fall by a third in the next century if one in 10 trees are resistant, but 60 per cent more trees would die if only five per cent were resistant.

If just one per cent were resistant, as previous research has suggested may be the case in Britain, 90 per cent more trees would die. That is based on a high chance of offspring trees inheriting resistance.

Professor Evans concludes: ‘The rapid reduction in the numbers of an abundant species will have implications for the dynamics of the forest, and the remaining population will be additional assaults from future pests and diseases and/or the evolution of the current disease.’

Nick Atkinson, Senior Conservation Adviser at the Woodland Trust said: ‘We welcome any attempts to improve the chances of identifying tolerant or resistant trees on the understanding that this might come at the cost of resistance to other diseases, or other negative effects.

‘We are beginning to see apparently healthy ash trees in areas heavily stricken by ADB and the question is to what degree any tolerance is genetically based.’

The full findings of the study were published in the journal Royal Society Open Science.