TY - JOUR

T1 - Decline of Fraxinus excelsior L. In parks of Saint Petersburg

T2 - Who is to blame - Hymenoscyphus fraxineus or Diplodia spp.?

AU - Shabunin, Dmitrii A.

AU - Selikhovkin, Andrey V.

AU - Varentsova, Elena Yu

AU - Musolin, Dmitry L.

N1 - Publisher Copyright: © 2020 Dmitrii A. Shabunin et al., published by Sciendo 2020.

PY - 2020/12/1

Y1 - 2020/12/1

N2 - The weakening and decline of European ash Fraxinus excelsior L. and other ash species have been recorded at different locations in the suburbs of Saint Petersburg, Russia. During the summer of 2019 and spring of 2020, samples from leaves, petioles, and shoots were collected from the weakened and declining ash trees in three parks in Pushkin and Gatchina and maintained in humid chambers to induce the fructification of fungi. In total, 30 taxa of micromycetes belonging to 23 genera were identified using methods of light microscopy. Hymenoscyphus fraxineus, a putative agent of ash dieback, was not recorded in the samples collected in the crowns of trees, but only on the petioles of the fallen leaves in spring. Out of all the micromycetes recorded, only coelomycetes from the genus Diplodia Fr. (in particular, D. mutila) can damage the branches of ash trees and, thus, be considered pathogenic. It is likely that H. fraxineus opens "the entry of infection"and Diplodia spp. cause the major weakening and decline of branches. The data obtained can significantly change our understanding of the causes of ash dieback and possible methods of ash stand preservation. The reason for the low pathogenicity and activity of H. fraxineus, as well as the possible role of ascomycetes Diplodia spp. in the dieback of ash stands requires further research.

AB - The weakening and decline of European ash Fraxinus excelsior L. and other ash species have been recorded at different locations in the suburbs of Saint Petersburg, Russia. During the summer of 2019 and spring of 2020, samples from leaves, petioles, and shoots were collected from the weakened and declining ash trees in three parks in Pushkin and Gatchina and maintained in humid chambers to induce the fructification of fungi. In total, 30 taxa of micromycetes belonging to 23 genera were identified using methods of light microscopy. Hymenoscyphus fraxineus, a putative agent of ash dieback, was not recorded in the samples collected in the crowns of trees, but only on the petioles of the fallen leaves in spring. Out of all the micromycetes recorded, only coelomycetes from the genus Diplodia Fr. (in particular, D. mutila) can damage the branches of ash trees and, thus, be considered pathogenic. It is likely that H. fraxineus opens "the entry of infection"and Diplodia spp. cause the major weakening and decline of branches. The data obtained can significantly change our understanding of the causes of ash dieback and possible methods of ash stand preservation. The reason for the low pathogenicity and activity of H. fraxineus, as well as the possible role of ascomycetes Diplodia spp. in the dieback of ash stands requires further research.

KW - Ascomycota

KW - ash dieback

KW - European ash

KW - invasive tree fungal pathogen

KW - tree health

KW - urban greening

UR - http://www.scopus.com/inward/record.url?scp=85102842180&partnerID=8YFLogxK

U2 - 10.2478/fsmu-2020-0013

DO - 10.2478/fsmu-2020-0013

M3 - Article

AN - SCOPUS:85102842180

VL - 73

SP - 43

EP - 51

JO - Forestry Studies

JF - Forestry Studies

SN - 1406-9954

IS - 1

ER -