Tree Health has hit the national headlines and local TV news this week. Ash die back, otherwise known as Hymenoscyphus fraxinea, has now been found in 10 sites in Cumbria including areas south of Derwent Water, Keswick, Cleator Moor, Ambleside and from Kentmere to Milnthorpe.
The spread of this infection is mapped ten kilometre squares called ‘hectads’ which are surveyed for infection. Reporting diseased trees helps combat the spread of the fungus and protection of our beautiful landscape. If you think you have spotted an infected ash please use the Forestry Commission Tree Alert system.
Caused by a fungus, ash die back first hit the UK in 2012, spread from Continental Europe and in nursery trees. There is currently no cure for the disease, which kills young trees in one season. Symptoms include leaf loss and crown die back – older trees may continue to live for many years with an infection.
There is concern that the publicity currently surrounding ash die back will lead to unnecessary felling and potentially exploitation by unscrupulous operators. Some ash strains are resistant and felling healthy ash is an ecological disaster. The Forestry Commission has a very informative advice section for landowners on their website.
The most important piece of advice however is not to rush to fell – especially older more mature trees. Older ash trees can survive infection and their value in the environment is not to be underestimated. There is no other single tree species that can fulfil the ecological role that ash does. Mature trees should only be felled/pruned if they are becoming dangerous as they die.
The advice is different for younger ash trees. Young saplings are invariably killed by ash die back and in stands less than 25 years old selective thinning of infected or retarded trees is advised in order to slow the spread of infection.
As we move into winter and the trees drop their leaves the symptoms to look out for are as follows:
• Brown or black retained leaf stalks
• Stem discolouration from the healthy silver in mature trees/olive green in young trees to a purple/brown
• A section of purple/brown die back surrounded on either side by healthy stem
• Diamond shaped lesions in the bark