Researchers looking for ways of breeding resistance to ash dieback, think that trees in the UK may have higher natural resistance to the fungus than those in Denmark, where over 90% of ash trees have been infected by the disease. A team of 30 scientists published their findings this week. They have been using a method of genome sequencing to compare the genetic traits of different ash trees from around the world, to try to understand their defence strategies.
While this has raised hopes of saving the ash, which is our most common hedgerow tree, there is an added complication. Even disease-tolerant trees might not be capable of resisting another threat to their survival, the emerald ash borer beetle. This beetle has devastated ash trees across the US and Russia and is spreading into Western Europe. Both the emerald ash borer beetle and the fungal infection which causes dieback, Hymenoscyphus pseudoalbidus (formerly called Chalara fraxinea) come from Asia, where trees have natural defences to them. It is thus hoped to isolate the genetic traits that help these Asian varieties to survive attacks.
Ash dieback spread across Europe over the last decade through airborne spores and importation of infected nursery plants. Its arrival in Ireland was first noticed in 2013 but it is believed to have been present for up to three years before then, giving it time to spread. It has now been found in every county and a €2.3m eradication effort seems to have failed. In response, Teagasc has initiated its own research project with the aim of developing disease-tolerant ash plants.
Ash trees have an important role in the Irish economy as they are the preferred timber for hurley makers. The disease is expected to have a major impact on the price of hurleys which are currently made from 75% imported timber. Ironically as the GAA strove to become self-sufficient in ash by 2018, new plantations of imported saplings helped spread the disease. Around 15,000 acres of ash were planted to supply the GAA's needs of over 50,000 trees per year. Now it is hoped that scientists can engineer a resistant variety of ash, to safeguard the future of this important tree.