It has already become widespread in other parts of Europe, including in some areas of Denmark, where it has wiped out between 60% to 90% of ash trees. The fungus causes the crown of the tree to die back and all the leaves turn brown.
The Telegraph reports:
Until last week, few had heard of ash dieback. Soon it may be too widespread to ignore. First spotted in Buckinghamshire in February, the fungus, Chalara fraxinea, has been identified at more than 40 sites from East Anglia — where it appears well established in mature trees — to Knockmountain in Renfrewshire.
The Forestry Commission plans to contain it by burning up to 100,000 trees and possibly banning the public from forests to stop them transporting fungal spores on their boots.
Amid claims from the opposition Labor Party that the government has been slow to react to discovery of the disease in Britain, Professor Ian Boyd, chief scientific adviser at the Department for Environment, Food and Rural Affairs, has been put in charge of a government task force dealing with the crisis. At the same time, a ban on the import and movement of ash trees took effect on October 29.
With up to 80 million ash trees at risk in Britain, this is indeed an emergency.
This threat to British trees has drawn parallels with Dutch Elm Disease (DED), which killed 28 million trees in Britain after arriving in the 1960s. Like ash dieback, DED is caused by a fungus that affects elm trees, but it is spread by the elm bark beetle. Both diseases are believed to be originally native to Asia, whence they were accidentally introduced into America and Europe.
In the United States, similar destruction is being wrought on lodgepole forests in the western US by the Mountain Pine Beetle. In northern Colorado and southeastern Wyoming alone, Mountain Pine Beetles have impacted more than 4 million acres since the first signs of outbreak in 1996.
Although the British Forestry Commission has plans to burn up to 100,000 trees, some researchers in Sweden, who have been studying this same fungus for over a decade, have a different idea.
From The Telegraph:
The Swedish study suggests that attempts to contain the disease by burning trees could be counterproductive. If resistant trees can grow alongside dying ones, burning all trees will “throw the baby out with the bath water”, leading to the eradication of native ash.
Prof Stenlid( of the University of Agricultural Sciences in Uppsala, Sweden) suggests a more cautious approach. “You should at least wait to find which ones are best off and then try to build a future from the ones that are not suffering so badly,” he says. “Otherwise you will remove the possibility of preserving the tree species because you will cut down the resistant ones.”
The Swedish team believes that tree and fungus will eventually form a “symbiotic” relationship, with healthy but infected trees, and this will lead to more resistant trees. Sadly, a lot of ash trees could die before then.
Scientists in the UK are also concerned that with so many trees dying, there could be serious consequences for other species.
Again, from The Telegraph:
University of East Anglia researcher Chris Panter said that if ash trees suffer large scale declines, 60 of the country’s rarest insect species could be at risk of being lost from Britain.
“As well as 80 common insects, at least 60 of the rarest insect species in the UK have an association with ash trees – these are mostly rare beetles and flies,” he said.
Whether it’s by burning trees or encouraging the tree and the fungus to form a symbiotic relationship, let’s hope this deadly fungus can be stopped before it changes the British countryside significantly.
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