Ash dieback (Chalara fraxinea) in Britain

Already 100,000 Ash trees have been destroyed

by Michael Smith (Veshengro), RFA, Ecofor

After the devastation wrought by the New Dutch Elm Disease to the Elm trees of Britain, the Bleeding Canker in Horse Chestnut trees and the problems with Cameraria ohridella, the leaf miner moth in the same, and Sudden Oak Death, now the Ash trees of the British Isles are under threat by yet another – possible devastating – disease.

Ash trees make up almost one third of Britain's tree stock – there are 80 million of them – and they are under threat from a deadly disease which is sweeping the forests of continental Europe sand have now arrived in the forests of Britain.

After much clouding of the issue and pussyfooting from the side of the government, it now appears that a staggering 100,000 trees have already been destroyed in an effort to stop the spreading.1

The Ash is the fourth most common tree in the countryside so this poses a terrible threat to the UK’s forests and to trees growing in parks and gardens. The first cases were discovered almost eight months ago. They came on trees imported from the Netherlands.

But it has also been found on British ash trees and it is thought that it can also be carried by the wind or be lying dormant for years

Ash_DiebackPhoto source: Forestry Commission

The disease, called Chalara fraxinea, is a fungus that causes leaf loss and crown dieback in affected trees, and it can lead to tree death.

First found in Poland 20 years ago, the fungus has gradually spread across Europe, reaching Denmark in 2002. There it led to estimated losses of between 60 and 90 per cent of Denmark’s ash trees.

The disease will devastate the landscape because if it spreads the trees will either die and rot or have to be destroyed, leaving huge gaps in forests and harming the wider eco-system, as they provide homes for birds, insects and mammals. It is second only to the oak tree in its popularity in the British countryside.

For now, effective from Monday, October 29, 2012, all imports of the Ash tree have been stopped and also no further planting of the trees in public forests will take place. A commission has been set up to examine the whole matter.

The Woodland Trust says: “Ash dieback is only one of numerous tree pests and diseases in the UK. With more than 15 separate pests and diseases listed on the Forestry Commission website as already present in the UK, it is crucial that the wider issue is tackled. The government must set up an emergency summit bringing together representatives from all areas of forestry, plant health and conservation – because today it's ash, but tomorrow yet another of our precious native trees could be at risk”.

Of great importance is also to introduce proper bio-security measures and to ensure that only trees raised from seeds in the UK, under monitored conditions, are grown for planting. And the same must go for all other trees.

We must, in fact, stop the importation of trees – all trees – and shrubs from abroad in order to ensure that diseases are kept at bay.

It would appear that New Dutch Elm Disease came into Britain with Elm lumber, imported as whole trees with bark on (lazy forestry practice), from the USA in the middle part of the last century after having first been exported with the same bad practice into the USA where the disease mutated in American Elms.

Sudden Oak Death also was brought into this country from abroad, and to all intents and purposes also from the USA, and in this instance via Rhododendrons.

It is, however, also true, as far as Ash dieback is concerned, the the spores of the fungus Chalara fraxinea are arriving in the UK on wind currents from the European mainland, such as from the Netherlands. Unfortunately there is little that we can do to protect against that kind of unwanted immigration.

Ash dieback is a reportable disease and anyone, especially woodland owners, managers of municipal parks, woodlands and open spaces, and in fact anyone else involved with trees, should immediately contact the appropriate authorities. The Forestry Commission research station at Alice Holt Lodge is the most central post of call in this case.

(C) 2012

1However, according to forestry sources in Germany felling and burning the trees will not prevent the disease nor lessen its impact as their efforts have shown. In fact, according to German forestry sources there is, basically, nothing that can be done.