Ash die-back (Chalara fraxinea)
News of a devastating disease of ash trees being discovered in the UK and Ireland earlier this year is raising concern as to its potential threat to ash trees on the island.
Ash dieback is caused by a fungus, Chalara fraxinea (confusingly, now more properly calledHymenoscyphus pseudoalbidus), and has led to widespread loss of ash in Europe in recent years. First discovered in Poland in 1992, more than 90% of their trees have died, a devastating loss. Since then it has spread slowly west to other European countries, notably Denmark where most ash trees have been affected. More recently the disease has been found in some 370 sites across the UK and Northern Island.
The disease mannifests itself on the bark of the ash with diamond shaped lessions around twigs and small branches. Leaves also turn black in summer on the affected branches, often in the tops of the tree initially. The only treatment is immediate felling and burning of the timber.
The disease is spread as the extremely small mould spores are blown by the wind from one tree to the next.
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 a number of locations in England and Scotland. In October 2012, Fera scientists confirmed a small number of cases in East Anglia in ash trees which do not appear to have any association with recently supplied nursery stock.
While there have been no reports of Chalara fraxinea in the Isle of Man to date, the disease has the potential to kill many thousands of trees if it reaches the island. Ash makes up around one quarter of the trees on the island, aproximately 300,000 trees, and can be found in woodlands and hedgerows across the Island. It is extremely important for wildlife, landscape value and biodiversity.
Fortunately, the IOM Woodland Trust grows its own ash stock from native seed, but we have now stopped further propagation and planting of ash trees until the situation is clearer.
The island is already suffering from Dutch Elm disease and sudden oak death (phytophthora ramorum)
Brenda Cannell MHK, a member of the Department of the Environment, Food and Agriculture, has said that this disease is extremely aggressive, and the Forestry dept. has ceased the importation of ash trees for forestry use. On Nov.5th 2013, a total ban on ash trees and products came into force on the Isle of Man.
The Forestry dept. currently grows ash trees from seed for its own use. These trees will be free from disease, and it is hoped by the general public not bringing in trees from abroad, that the Island will remain disease free.
Mountain ash is not related to common ash and is, therefore, not affected or susceptible to the disease.
For more information, please look at the UK Forestry Division website where there is a video of ash tree die-back and what to look for.
Please phone the Island’s Forestry dept. if you suspect that you may have Ash Die-back on your land. (801263)