What is this diease?

Ash dieback, sometimes called ‘chalara dieback of ash’, is a slow-spreading but devastating fungal disease that targets the European ash (Fraxinus excelsior) and related species.

The fungus responsible for the disease, Hymenoscyphus fraxineus, is of far east origin, and native ash species, such as the Chinese and Manchurian ash, have developed effective immunity to it.

But around 30 years ago, the fungus became widespread across Europe, killing species of ash that had no such immunity. While Hymenoscyphus fraxineus spores can travel tens of miles on the wind, it is thought that the fungus largely came into the UK via unregulated imports of ash saplings. Since it was discovered in 2012, in south east England, these imports have been banned. But the damage has already been done.

Ash dieback can kill young and coppiced trees incredibly quickly. Older ashes can linger on, but will usually become weak and susceptible to a host of other diseases.

What is ash dieback expected to do to the UK’s ash population?

Ash dieback disease is predicted to wipe out up to 80% of the UK’s ash trees. This would be tragic for the country’s biodiversity as many species rely on ash trees to survive. Individual ash trees and hedges also act as vital connecting corridors between woods and forests. Ash is also an important tree for the hardwood industry.

What is ash dieback going to do to the economy? Considering both direct costs and the less obvious costs of ground clearance, loss of air purification, etc. the combined financial impact of the disease could run into tens of billions of pounds.

There is some good news though. Signs of developing immunity to ash dieback have been found on some trees, suggesting the ash could eventually make a comeback, although this could take 50 years or more.

What are the symptoms of ash dieback disease?

There are several telltale signs associated with ash dieback. These are:

  • The appearance of dark patches on ash leaves in the summer, especially near the base or midrib. This is evidence that the fungus has penetrated the leaves.
  • Blackened and wilted leaves. Once the fungus has taken hold, it infects the tree’s nutrient transport system, starving leaves of goodness.
  • Brown, diamond-shaped wounds, especially where branches meet the trunk. Under the bark, you may find that the underlying tissue has also turned grey-brown.
  • Perennial cankers that may quickly encircle and kill stems.
  • Large scale dieback of the crown in summer, with leaves, stems and whole branches dying.
  • Epicormic growth. This is where a host of dormant shoots near the base of the tree start growing. It is a common response to stress.

What is ash dieback going to do to my land?

If you spot signs of ash dieback in your ash trees, it is important to act quickly. If yours is the first example of ash dieback in your area, you must also report the infection to either the Forestry Commission or the Animal & Plant Health Agency (APHA). To make this easier, you can use the TreeAlert service to file your report.

To prevent future sporing, you will need to thoroughly clear your land of leaf litter, either by burning the leaves, burying them under four inches of soil or deep composting.

Most ash trees on your land will unfortunately need to be felled, although young ash trees can sometimes be saved. With our specialist knowledge of ash dieback, Arborcure can inspect your ash trees and carry out felling where necessary.

Please contact us as soon as possible to help protect both your own land and the wider environment.