After a series of initial press releases, information for landowners on how to deal with Ash dieback has been difficult to find and lacking in any clear advice on how to manage the problem. The initial hope was that because of climatic and genetic reasons Ash in the UK would prove more resistant than across the rest of Europe.
It is now clear that this is not the case and that based on research in Denmark and Poland we can expect the rapid decline and death of at least 90% of our forest Ash and 60-80% of the same species on our roadsides. The impact of this is that ten times more trees will be lost than as a result of Dutch Elm Disease; the disease is evident from north central Scotland to the south coast of England.
The Impact of the Disease
The first signs of the disease are usually leaf loss or stem lesions; often in the first two to three years this will not appear to be particularly significant, however a tree does not recover, and the leaf loss will continue over years 3-5 with larger branches failing to flush at all and crown thinning and dieback becoming clearly evident.
There are several options for management, but it is clear that doing nothing should not be one of them, unless you have an isolated wood with no access and your objective is to create deadwood. The photograph to the right is of an Ash woodland in Kent where the disease was not identified, no management took place, and Honey fungus caused complete failure and reduced any timber value. It is likely that the disease first attacked 10-12 years ago, but initially went unnoticed.
Where Honey fungus is not a threat there is some evidence that larger trees can continue to live for a few years after the first signs of the disease, although growth will be greatly reduced, and the tree instability and risk of catastrophic failure greatly increase. Additionally, thinning around larger specimen trees can slow the progress of the disease and will allow you to identify any resistant trees, but is unlikely to have any benefit on a large scale. The key to managing any retained Ash will be to carefully monitor the progress of the disease and act with urgency when crown dieback reaches a point where risk of branches dropping, and increased harvesting costs outweighs any benefit of retaining the trees.
Equally, where your objective of woodland ownership is to generate income, the best advice must be to take immediate action to manage your Ash before the timber value decreases and harvesting cost spiral due to the increased risk to machinery and operators presented in felling dead and broken trees. Currently, markets for quality saw-log material, firewood and biomass are positive and even those sites where the disease has caused tree death should in the short-term be able to show a positive financial return. The financial gamble is all about timing; as the disease becomes more evident, the market will saturate, and prices will drop back from their current level, in other words timber coming to market early is likely to attract the best prices.
For more information on managing or removing Ash
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Issue date 06/04/1
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