Ash dieback: the end of British woodlands as we know them?

Oct 25, 2012

Deadly fungus that killed 90 per cent of ash trees in Denmark is being dubbed the new Dutch elm disease

Humphrey Bolton

ASH DIEBACK, a disease that has the potential to devastate Britain’s ash tree population, has been found for the first time in mature UK woodland.

Until now ‘chalara dieback’, as it is also known, had only been recorded in a few nursery specimens in this country. The discovery of what is being termed “the new Dutch elm disease” – which killed more than 25m elms in the UK from the 1960s – has prompted some environmentalists to warn this could be the end for ash trees in Britain.

Ash dieback is a disease caused by the fungus Chalara fraxinea. The tiny spores attach themselves to the leaves, which turn brown and fall, leaving the distressed tree so weakened that eventually it dies. Evidence suggests the spores can travel up to 20km, floating on air currents.

Chalara fraxinea is known to kill as many as nine out of 10 of the plants it infects. The fungus has spread across Germany, Poland and other parts of northern Europe in the past seven years, and has wiped out around 90 per cent of ash trees in Denmark.

Ash, along with oak, is a key constituent of mature British woodlands. With an estimated 80m trees, the ash population makes up nearly a third of the forests and other woodland areas in the UK.

Norman Starks, the Woodland Trust’s operations director, told The Guardian that a loss on the scale already seen in Denmark could have a devastating effect on Britain’s countryside. “It would be an environmental disaster,” he said. “The impact on woodland biodiversity would be huge.”

Until recently, ash dieback had only been found in a handful of young trees in nurseries and newly planted woodlands. The Forestry Commission thought it could control the disease by stopping imports of saplings and by forcing nurseries to carry out checks for the fungus.

However, the disease has now been found in ashes at two sites in East Anglia, the Woodland Trust's Pound Farm woodland in Suffolk, and Norfolk Wildlife Trust's Lower Wood reserve in Ashwellthorpe. Any hope of containment has been dashed.

According to The Guardian, there is no effective treatment for ash dieback. To try and stop its spread, imports of ash saplings from mainland Europe will have to be banned and affected trees in this country felled and burnt. The Woodland Trust has called for an emergency summit or taskforce to be set up by the Government to tackle tree diseases.

“It’s the international plant trade that has created this threat to the UK’s ash trees,” added Starks. “We must stop buying cheap saplings from the giant nurseries in eastern Europe where the fungus is rampant.”

The BBC reports that a government consultation on whether to ban imports of ash trees in the UK is set to close on Friday and it is widely expected that legislation will be passed in time for a ban to be in force by mid-November.

The Horticultural Trades Association has urged members to abide by a voluntary moratorium on importing ash trees for planting in this country.

So far the discovery in the wild is limited to forests in Norfolk. Roger Coppock, head of analysts at the Forestry Commission, told the Today programme that the Commission has already dispatched teams in the countryside to inspect ash trees for symptoms so they can establish the spread of the disease.

Dr John Morgan, head of the Forestry Commission’s plant health service told The Daily Telegraph there is a chance the East Anglia case is an isolated one but others fear it is already too late.

The environmental blogger George Monbiot condemned the goverment’s “nine months of dithering” since the disease was first discovered in the UK in February, taking to Twitter to say it may be too late to “shut the stable door” on ash dieback.

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