“Green tree thinking” and the problems of Ash Dieback
Andy Nicol, MD of Nicol: The Tree Specialist, has over 25 years of experience working with trees. That makes it emotionally hard to deal with ash dieback and its impact on Cumbrian ash trees. But it also gives Andy the knowledge and skills to make the right decisions about tree care or, if needed, safe felling.
“Ash dieback is highly destructive,” says Andy, “but these trees are hugely valuable to the environment, often supporting up to 1000 other species, such as lichens and invertebrates. My job is to assess and minimise the damage caused by the disease, extend the life of those trees that are showing early signs of its impact if I can and all while ensuring that there is no threat to public safety from those that are more severely infected.”
Where did Ash Dieback come from, and what causes it?
Ash dieback arrived in Europe from Asia during the 1990s and spread rapidly. It is caused by a fungus (Hymenoscyphus fraxineus, formerly known as Chalara fraxinea) that progressively damages the vascular tissues of the ash tree. This causes particular branches to “die back” by blocking their supply of water and nutrients. This ultimately causes leaf loss and canopy decline and, in some cases, the death of the tree.
Young trees are more susceptible and can die within a couple of years of infection while more mature trees take longer but often end up succumbing to secondary infections. “My prime role is the assessment and surveying,” explains Andy. “The resulting tree management strategy includes a tree safety report for each property. We also make recommendations on the priorities for safety-critical works so that the business can plan its tree management budget accurately.”
What are the symptoms of Ash Dieback?
Once infected with ash dieback, an ash tree can show a variety of symptoms, usually with dark patches or lesions on the bark, followed by signs on the summer leaves such as wilting or dark spotting. In practice, affected ash trees might lose some of their leaves at the top, but the lesions are the main thing to look out for as many trees show little sign of ash dieback on their leaves at first.
The fungus grows in fallen leaves in the autumn so careful clearing of leaf litter from around the base of ash trees can reduce the levels of spores present, giving the tree a better chance of surviving longer but it is only ever able to delay the disease. There is no known “cure”.
Do you need to take action and what types of treatment are available?
Reasonable public safety has to be the top priority when assessing what action to take on the ash trees on your land. If you’ve infected ash trees near public buildings, overhanging roads or in well-used public spaces, you need to take action. When the risks are lower, for instance, in open ground with no public access, trees an be left to decline naturally so that they continue to contribute to the broader eco systems.
Even if action is required, a careful assessment and a bit of “green tree thinking” might mean that complete felling is only one option. We’ve worked recently to remove deadwood that was showing symptoms of dieback on an established tree and we’ve reduced the crowns of other trees in field settings to reduce the risks while keeping as much of the tree as possible.
Images of the symptoms of ash dieback
If you think you may have an issue with Ash Dieback, get in touch to find out how we can help you manage this.
