In Slobozhanshchyna, foresters are searching for solutions to the problem of dying ash trees. "Ash trees, ash trees, I see you beyond the village by the road..." - these words from a popular song came to mind in Sumy region, specifically in Trostianets Forestry, where chief foresters from regional forestry enterprises gathered with scientists from the Ukrainian Research Institute of Forestry and Agroforestry and specialists from the State Specialized Forest Protection Enterprise "Kharkivlisozakhyst" to discuss the painful problem of ash dieback.

The ash tree, one of the living symbols of Ukraine, so soulfully sung by poet Mykhailo Tkach and composer Oleksandr Bilash, can no longer be seen "in beauty when the morning glistens with dew." More and more ash trees (not just in Slobozhanshchyna) are getting sick and dying. What can counter this misfortune?

Necrosis or Borer?

In recent years, foresters in Sumy region have been fighting the top bark beetle that destroyed mature pine forests. Today, the population of this pest has decreased, but a new threat has emerged for ash trees. To preserve ash plantations, understand the nature of infection spread, and find practical control methods, the Forestry Department organized a special seminar.

The disease affecting the trees discussed at the meeting is ash dieback (Hymenoscyphus fraxineus). This fungal infection causes mass dieback and tree mortality. Besides fungal pathology, ash plantations are also being destroyed by the emerald ash borer, causing enormous financial losses to the forestry sector even in the most powerful countries.

Participants of the seminar in Trostianets Forestry had the opportunity to visit forest areas and see firsthand the threat posed by this dangerous disease.

"This area is infected with ash dieback and is designated for final felling," said enterprise director Viktor Zubko. "Six months ago, nothing like this was observed here. The stock per hectare is 510 cubic meters, meaning the plantation was well-maintained and entered felling in quite productive condition. But due to the disease, trees are beginning to dry out and lose their commercial qualities."

The Scientific Perspective

Mass dieback of ash plantations has been observed in recent years throughout Europe and Ukraine. The first question for scientists is: what does science know about ash dieback that has caused such rapid deterioration of ash condition?

"Ash dieback is caused by a foreign fungus from Japan - Hymenoscyphus fraxineus," explains Kateryna Davydenko, senior researcher at UkrNDILGA. "It arrived in Poland around 1992 and quickly spread across the continent. In Ukraine, it was identified in 2010 using molecular methods in samples from Kharkiv region plantations, later in central and western regions."

Young trees dry out and may die within 1-3 years after infection, while older plantations die gradually. This fungus is a typical example of so-called "invasive" species that accidentally or intentionally arrive from other continents and begin to spread uncontrollably as they have no natural enemies in their new location.

Unfortunately, no preparations are effective against ash dieback as the pathogen develops deep in the wood, quickly leading to tree death, and the infection persists in fallen leaf petioles.

European scientists studying the problem have unanimously recognized: the only way to preserve ash in Europe is to identify resistant trees and use them to create genetic reserves that will be resistant to this disease.

The Emerald Ash Borer Threat

Another invasive pest threatening ash trees is the emerald ash borer (Agrilus planipennis), also of Asian origin. It reached the US in 2002 and within 20 years has occupied almost the entire country and half of Canada, severely damaging most ash species and some other trees, causing millions in losses.

In the US and Canada, measures to limit its spread include constant monitoring using pheromone traps, visual inspections, model branch examinations, removal of infested trees, and public awareness campaigns. American scientists found that the fastest way the borer spreads is through firewood transportation.

The emerald ash borer was detected in Moscow (Russia) around the same time and gradually moved toward Ukraine and Belarus. In summer 2019, scientists from Kharkiv National University confirmed its presence in Ukraine in ash plantations in Bilovodske Forestry and adjacent forest belts in Luhansk region.

By the end of 2019, the damaged area was 8.3 hectares - all ash trees in this area were cut down and burned according to current legislation. In 2020, the emerald ash borer spread throughout the region and was found in four districts of Luhansk region, declared quarantine zones for ash wood and its products.

Conclusion

There is no doubt that the emerald ash borer will spread across Ukraine and will be very difficult to stop. US scientists now have opportunities to implement biological ash protection methods using parasitic insects, but this is a long-term and very expensive program. Moreover, the emerald ash borer is a quarantine pest, so infested trees must be destroyed according to current legislation requirements.