Living with the Impact of Ash Dieback Disease – Local Mitigation Practices Against Hymenoscyphus Fraxineus on the Island of Ireland

ABSTRACT:Ash trees (Fraxinus spp.) have considerable environmental, cultural and economic value on the island of Ireland. However, the species is currently succumbing to widespread damage from the invasive fungal pathogen Hymenoscyphus fraxineus (T. Kowalski) Baral, Queloz and Hosoza, which has swept across Europe. This pathogen is the causal agent of ash dieback disease, an infection with symptoms that were initially reported in Poland in the early 1990s. Hymenoscyphus fraxineus has since spread across Europe and now largely matches the natural distribution of F. excelsior. The first detection of the disease on the island of Ireland was in 2012 at a forestry plantation in Co. Leitrim, although it is unknown when the disease was first introduced onto the island. The pathogen has now been detected in all 26 counties in Ireland and 6 counties in Northern Ireland, and it is considered too difficult to eradicate. Management of the impact of the disease is now of vital importance. Considerable research efforts have been made internationally to understand the biology of H. fraxineus and to develop management strategies against it. This review provides an update of current knowledge of H. fraxineus biology and epidemiology. It explores examples of mitigation techniques that have been trialled in Europe, in order to identify strategies that may be feasible for disease management at a local level on the island of Ireland. Finally, five key avenues of research are outlined that have the potential to provide breakthroughs in methods to protect valuable F. excelsior resources.