Situation and perspectives of European ash (Fraxinus spp.) in Ukraine: focus on eastern border

Abstract

The health condition of European ash (Fraxinus excelsior) stands in Ukraine has become worse since 2006. Firstly, in 2011 an alien invasive pathogenic fungus Hymenoscyphus fraxineus was identified in the eastern part of the country and, subsequently, its presence was confirmed in the western and central parts. The aims of our research were to evaluate the health of ash trees and identify the main causes of ash decline in different regions of Ukraine with emphasis on ash dieback and its association with collar rots.
 Results showed that since 2013 the number of trees with ash dieback symptoms has been gradually increasing, reaching up to 92 % in 2018. Total mortality due to ash dieback was up to 9 % in 2018. Disease intensity remains high in northern and central Ukraine comparing with the east. Branch dieback, collar rots, epicormic shoots and bacterial disease of ash occurred more often in the eastern region, some symptoms were observed simultaneously. Ash bark beetle galleries, as well as foliage browsing insects, were found mostly in weakened and/or dying trees.
 It was indicated that collar rots significantly increase the mortality of ash trees. Armillaria spp. fungi were found to be frequently associated with ash dieback on living stems and fallen trees in 2017, causing high rates of mortality in the northern and central regions. For further ash conservation and breeding programmes, resistant trees in severely damaged regions should be selected to preserve genetic diversity in ash populations.
 
 Keywords: Fraxinus excelsior, ash dieback, collar rot, bacterial disease, epicormic shoots, Hymenoscyphus fraxineus, Armillaria spp.

Invasion of Emerald Ash Borer Agrilus planipennis and Ash Dieback Pathogen Hymenoscyphus fraxineus in Ukraine—A Concerted Action

“…Simultaneously, the frequency of occurrence of ADB-symptomatic trees has been assessed based on the presence of typical bark necroses on branches and shoots, shoot dieback, and wilting leaves. The presence of ADB (Hymenoscyphus fraxineus, formerly H. pseudoalbidus) was confirmed earlier in the research regions using fungal culturing followed by ITS rDNA sequencing [18,19] and using ITS rDNA sequencing directly from the infected tree tissues [9,20]. Based on information acquired during the surveys, locations of 10 monitoring plots of the present study were selected (Figure 1).…”

Dead Better than Alive—The Case of Retention Trees and Tree-Related Microhabitats in Young Stands of Hemiboreal Forests in Latvia

“…Most of the snags were Ulmus glabra (50% of all snags). The formation of deadwood for these species was caused by the dieback [37][38][39], thus undermining their importance in the future as current deadwood decays away. In most cases, snags provide more TreMs than living trees of comparable size [14,18,40].…”

Occurrence of Ulmus L. in the different forest site conditions of eastern Ukraine

“…In the forests of Ukraine, the occurrence of elm species in relation to their resistance to various natural and anthropogenic factors has been little studied (Maslovata et al 2016, Yavny & Puzrina 2018, Puzrina & Yavny 2020. Taking into account the increased mortality of English oak (Quercus robur L.) and common ash (Fraxinus excelsior L.) in many regions (Brown et al 2018, Davydenko et al 2019, Enderle et al 2019, Gagen et al 2019) and a high ecological value of Ulmus sp. (Collin & Bozzano 2015, Matuszkiewicz 2015, it is necessary to assess their current distribution in the forest fund of individual regions and their sustainability.…”