A deadly tree fungus has been detected in Cornwall for the first time as the number of infected sites nationwide doubled in the past month to almost 300.
The confirmed case of ash dieback was found in a recently-planted site near Camborne, the Forestry Commission has revealed.
The disease, which it is predicted will wipe out 90% of the species, scarring the unique hedgerows of the Westcountry as it spreads, is now present in Devon and Cornwall.
Government figures released last week showed a steep rise in detected cases, though the region has been be less badly affected than the South East, where wind-blown spores are said to have worsened the spread.
David Rickwood, site manager for the Woodland Trust in Devon, has predicted the fungus will effect widespread "landscape change" across the region.
He said a handful of fresh cases had been identified as part of last month's audit, all of them in new plantings.
However, he claimed this was the result of a huge audit rather than evidence that the disease was spreading in the countryside, adding that prevailing westerly winds might help prevent stem its rapid movement in the wild.
"We are in a much better position than the rest of the country," he said.
"It is partly distance but it could also be the fact that we have not been sourcing trees from disease hotspots.
"I am pretty sure that all the cases in the South West are in nursery stock – and they are now destroying the trees which cannot be sold."
Dartmoor National Park is anticipating having to rip out and burn the 10% of its woodland accounted for by ash, which is concentrated in areas such as Belstone Cleave.
Brian Beasley, the national park's trees and landscape officer, told an authority meeting on Friday that an infected site had been confirmed in a newly-planted woodland owned by the Woodland Trust, to the west of Exeter and near Dartmoor's eastern boundary.
He also warned that lichens of national and international importance which live in ash bark in places such as Buckland-in-the-Moor, are at risk.
The fungus was first identified in the UK in February 2012 in a tree imported from the Netherlands to a nursery in Buckinghamshire.
Across the UK, the disease has been identified in 291 sites,17 of them nurseries.
Chalara fraxinea has now been found at 136 sites linked to imported plants and a further 155 sites in the wider environment, which government scientists think were infected by wind-blown spores from continental Europe.
Environment Secretary Owen Paterson, has set out plans aimed at controlling the disease, including keeping the ban on the import or movement of ash trees in place.
His department is also considering appointing a "tree tsar" – a chief plant health officer equivalent to the chief veterinary officer who leads the response to animal disease threats such as foot and mouth and bluetongue.
"The plan I have set out shows our determination to slow the spread and minimise the impact of Chalara," said Mr Paterson, who predicted in November it would be impossible to eradicate the fungus.
"It will also give us time to find those trees with genetic resistance to the disease and to restructure our woodlands to make them more resilient."
The measures were criticised by the National Trust as "limited and weak", too focused on minimising costs and "surrendering the British landscape to this disease."
Simon Pryor, director of the natural environment at the National Trust, said: "The limited actions and weak commitments set out in the (Government) plan will not be enough to control the spread of the disease – it's far too little, too late.
"We are alarmed to see the government is even wavering about continuing its programme of tracing, testing and destroying infected young ash trees.
"It is also disappointing to see the Government is proposing almost no action in areas of the country already infected."
Woodland Trust chief executive Sue Holden said there was "a distinct lack of political interest" in supporting the UK's natural infrastructure, adding that the Government is playing "scientific catch up" and is "completely unprepared for the crisis".