The slow death of the beautiful ash tree
Mature ash trees were thought to be a symbol of the well-being of the land itself. Picture: Pat McCarrick
If my father had a quiet Sunday in winter, he would take his gun and walk the land. This usually meant walking the boundary of our farm, taking in the places most likely to provide him with a shot. One such place, along the River Moy, was a location he called The Ash Bush. He always maintained it was a good spot to raise a mallard.
This ash bush was a landmark on our farm; everyone knew where it was; the mention of it described a location as well as the tree itself. Every farm in and around the Ox Mountains has a similar ash bush or ash tree. A place where childhood swings were hung, where initials were carved and around which lambs found their favourite place to romp in spring.
The Tree Council of Ireland gives a short introduction to the ash, our most common tree. The ash, while ancient, has remained our forever friend; loyal and trusted.
Mature ash trees were thought to be a symbol of the well-being of the land itself. Noted for their strong and flexible timber and the delicacy of their leaves, ash trees also had associations with healing and fertility through their symbolic link with water and wells. But this is not a happy story nor does it have a happy ending.
All seemed to be well in the world of the ash, a tree that seemed supple and powerful in equal measure, until one day a plague arrived to threaten its very existence – the plague of ash dieback.
is the fungus that causes ash dieback, a chronic disease of ash trees characterised by leaf loss and crown dieback in infected trees. The fungus was first scientifically described in 2006. It is now believed that the trees reported to have died in Poland in 1992 were infected with ash dieback. The disease is now widespread in Europe, with up to 70% mortality rates recorded in woodlands.
According to Teagasc, ash dieback was first detected in the Republic of Ireland in October 2012 on plants imported from continental Europe. The disease is now prevalent throughout most of the island and is likely to cause the death of most ash trees over the next two decades.
Teagasc is currently conducting research to establish a gene bank composed of genotypes of ash tolerant to ash dieback with the aim of producing planting stock for forests and hedgerows in Ireland. Their efforts, however, are showing very little promise in the short term. Teagasc notes:
In Ireland, the loss of the ash tree will have an economic cost of almost €2 billion. The Woodland Trust in the UK paints a bleak picture for the future of the ash tree and the losses associated with its disappearance. All in all, it is not a pretty picture.
While younger trees succumb to the disease quicker, in general, all affected trees will have these symptoms: leaves develop dark patches in the summer and then wilt and discolour to black, leaves might shed early and lesions develop where branches meet the trunk.
The fungus overwinters in leaf litter on the ground, particularly on ash leaf stalks. It produces small white fruiting bodies between July and October which release spores into the surrounding atmosphere. These spores can travel on the wind for up to ten miles, sticking to and entering ash leaves. The fungus then grows inside the tree, eventually blocking its water transport systems and causing it to die. The tree can fight back, but year-on-year, repeated infections will eventually kill it.
Up to this point, there is no effective strategy for managing the disease, and most countries that have tried to control its spread have been unsuccessful. The removal of trees in infected areas has little effect as the fungus lives and grows on leaf litter on the forest floor.
Research at the Swedish University of Agricultural Sciences suggests that the deliberate destruction of trees in an infected area can be counterproductive as it destroys the few resistant trees alongside the dying ones.
One approach to managing the disease may be to take branches from resistant trees and graft them to rootstock to produce seeds of resistant trees in a controlled environment. A Lithuanian trial aimed at identifying disease-resistant trees has resulted in the selection of 50 such trees for the establishment of breeding populations of European ash in different provinces of Lithuania. A breeding programme for resistant trees is a viable strategy but the process of restoring the ash tree population across Europe with resistant trees is likely to take decades. By then, all our native ash trees will be dead and gone.
Teagasc also has some information on an owner's responsibility for trees damaged because of ash dieback. One concern, as the disease spreads, is the risk of accidents occurring due to trees falling or branches dropping off. The danger will increase as older trees become infected. This will have serious implications for landowners, particularly if the trees are growing close to public roadways.
It seems that our ever-faithful friend, the ash tree, is destined for a slow and painful death. It is the death of an ancient hero, a whole ecosystem, a national institution. In Scandinavian mythology, the ash tree was known as Yggdrasil - Tree of the World, the giant ash tree that linked and sheltered all worlds. It was also known as The Tree of Rebirth and Healing, and to encounter it meant regeneration and rebirth. How ironic that a tree with such hopeful and healing connotations should find itself in a desperate fight for survival.
