As the government bans ash imports to halt the spread of "dieback"and fells 100,000 trees affected by the disease , Channel 4 asks what effect it will have on the UK.
Please wait while this video loads. If it doesn't load after a few seconds you may need to have Adobe Flash installed.
What is the threat, and where has it come from?
Chalara fraxinea - or ash dieback to give it its common name - was discovered in Poland in 1992 and has since spread to other European countries.
Denmark is one of the hardest hit countries. Since its discovery there in 2005, more than 90 per cent of its ash trees have been destroyed.
How does the disease spread?
Although there is no clear scientific evidence yet, it is understood that fungus spores are spread by wind - as far as 10 miles by strong gusts.
When were the first British cases reported?
A Buckinghamshire nursery was the site of the first ash dieback discovery in February 2012 - it was found in saplings it had imported from the Netherlands.
Since then, more than 20 different woodland sites have reported cases. It has also been sighted in mature trees for the first time, in separate sites in Suffolk and Norfolk.
What is being done to stop the problem?
Imports of ash trees are to be banned from Monday in an attempt to stop the spread of a disease The Forestry Commission and the government is assembling a task force to look at the problem.
How many ash trees are there across the UK?
An estimated 80 million, taking up around 30 per cent of woodland across the country. By contrast, Dutch elm disease killed around 25 million elm trees between the 1970s and the 1990s.
How will the loss of ash trees affect our environment?
Fallen ash leaves are an ideal source of nitrogen and other feeds for animals and other plants. Many bluebell woods are mainly ash, as the trees' branches are ideally spaced for light to pass through and let the bluebells grow. Owls and woodpeckers also depend on ash trees.
How important are ash trees to our timber industry?
Ash wood has two main practical uses. It is excellent firewood, and burns well even before being dried.
The other main use of ash wood is when both strength and a little flexibility are needed. In sports, ash is commonly used for hockey sticks, oars, snooker cues and for the sticks known as hurleys used in the Irish sport of hurling. "The clash of the ash" is a familiar phrase to Irish sports journalists trying to convey the excitement of a hurling match.
The frames of Morgan sports cars are also made of ash.
How do you know if an ash tree has the disease?
Blackened leaves are the biggest indicator. Trees affected need to be felled and burned to prevent any further spread, according to government advice.
25 October 2012