“Ash Dieback” is a serious disease of ash trees caused by a fungus called Chalara fraxinea. The disease causes leaf loss and crown dieback in affected trees, and usually leads to tree death.
Chalara fraxinea is potentially a very serious threat. It has caused widespread damage to ash populations in continental Europe, including estimated losses of between 60 and 90 per cent of Denmark’s ash trees. We have no reason to believe that the consequences of its entering the natural environment in Britain would be any less serious. Chalara dieback of ash is particularly destructive of young ash plants, killing them within one growing season of symptoms becoming visible. Older trees can survive initial attacks, but tend to succumb eventually after several seasons of infection.
Local spread, up to some tens of miles, may be by wind. Over longer distances the risk of disease spread is most likely to be through the movement of diseased ash plants. Movement of logs or unsawn wood from infected trees might also be a pathway for the disease, although this is considered to be a low risk.
In February 2012 it was found in a consignment of infected trees sent from a nursery in the Netherlands to a nursery in Buckinghamshire, England. Since then it has been found in young ash trees in a number and variety of locations in Great Britain, including urban landscaping schemes, newly planted woodland, and more nurseries.
Because ash trees have many genetic variants and occur all across the UK, they come to leaf at different times. In general, they come into leaf later in spring than many other trees, often as late as the end of May. So if an ash tree does not have any leaves on it in April and May, it does not necessarily mean that it is diseased or dying, but by mid-June all healthy ash should be in full leaf.
You are not required to take any particular action if you own infected ash trees, unless the council or plant health authority serves you with a statutory Plant Health Notice. You should, however, keep an eye on the trees’ safety as the disease progresses, and prune or fell them if they or their branches threaten to cause injury or damage. You can also help to slow the spread of the disease by, where practicable, removing and disposing of infected ash plants, collecting up and burning, burying or composting the fallen leaves.
For more information or if you suspect your ash tree to be diseased please call us for a site visit.
Please call 01484 685098 or 07973 420820 or email firstname.lastname@example.org