Farm Ireland
Independent.ie

Thursday 8 December 2016

Ireland is losing its battle to save ash trees from killer fungus

Published 21/11/2016 | 13:44

Dead leaves hang on an infected Ash tree
Dead leaves hang on an infected Ash tree

A disease affecting ash trees is continuing to spread across the country, despite control efforts by landowners and the Department of Agriculture.

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Chalara or Ash Dieback disease is a disease of ash trees caused by the fungus Hymenoscyphus fraxineus and it has spread rapidly across Europe in recent years.

And the latest figures from the Department of Agriculture show that year on year that there is a continuing rise in the number and geographic distribution of confirmed findings nationally and is present in every county.

The origins of the disease are still unknown, but scientists have suggested the disease may have been introduced to Europe from eastern Asia.

Ash trees affected by the disease suffer wilting foliage, crown dieback and bark lesions.

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The disease can kill an infected tree directly as over time necrotic lesions gradually encircle and permanently damage the phloem: (the innermost layer of bark) which is the layer of living tissue that carries organic nutrients to the others parts of the plant, or indirectly by weakening the tree to the point where it becomes more susceptible, and succumbs more readily, to attacks by other pests or pathogens, especially Armillaria fungi or honey fungus.

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Minister Creed recently said the spread come despite the positive effects at local level of the eradication actions undertaken to date, both by affected landowners supported by the Reconstitution Scheme or directly by the Department itself.

By June of this year, at a time when the targeted and systematic summer surveys were still underway, the initial results were already such as to confirm the presence to a greater or lesser extent of the disease in all 26 counties.

Another factor is that initially the findings were in imported ash trees. Later the disease was found in native hedgerows beside infected imported ash trees.

However, now the Department is now finding the disease in native hedgerows where there is no obvious introduced source of infection nearby.

Over half the recent findings in forest plantations are in ash trees of native Irish origin.

The Department of Agriculture is actively supporting a number of research projects into disease, in particular projects with a key long-term focus of developing an ash tree breeding programme to identify trees that show strong tolerance and or resistance to the disease and the genetic basis for tolerance.

Minister Creed says that it is through such programmes that a long-term strategy for ash can be identified and supported.

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