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Dieback of Fraxinus excelsior in the Baltic Sea Region

associated fungi, their pathogenicity and implications for silviculture

Bakys, Remigijus (2013). Dieback of Fraxinus excelsior in the Baltic Sea Region. Diss. (sammanfattning/summary) Uppsala : Sveriges lantbruksuniv., Acta Universitatis Agriculturae Sueciae, 1652-6880 ; 2013:10
ISBN 978-91-576-7767-9
[Doctoral thesis]

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This thesis is comprised of three main studies: (1) the wood-inhabiting fungi found in declining European ash (Fraxinus excelsior L.) and their pathogenicity; (2) the relationship between F. excelsior phenology, site density and the susceptibility to the dieback; and (3) the potential of natural regeneration of dieback affected ash stands. The studies that are presented here were conducted in Denmark, Lithuania and Sweden.

Combination of different sampling and detection methods revealed a high diversity of fungi in both healthy looking and symptomatic tissues of declining F. excelsior. The most frequently detected fungal taxa were Alternaria alternata, Armillaria cepistipes, Aureobasidium pullulans, Botryosphaeria stevensii, Cladosporium cladosporioides, Cryptococcus foliicola, Epicoccum nigrum, Gibberella avenacea, Hymenoscyphus pseudoalbidus, Lewia sp., Phoma spp. and Phomopsis sp.

In pathogenicity tests nine fungal taxa caused symptomatic discoloration of bark and cambium on F. excelsior saplings, though only H. pseudoalbidus infected substantial proportion (50-100%) of tested trees.

The seasonal pattern of ash dieback severity, attributed to crown damage of F. excelsior trees, significantly increased towards the end of the investigated growth season. Severity of dieback symptoms was more pronounced in the unthinned stands, but otherwise was not related with stand density. However, susceptibility of F. excelsior to the disease was found to be dependent on the flushing (bud-bursting) phenology of the trees - late-flushing F. excelsior were most severely affected.

Our study demonstrated that vigorous natural regeneration of F. excelsior in examined clear-felled sites cannot be expected. Regenerating F. excelsior exhibited abundant dieback symptoms. The species composition in sites with long disease history is likely to shift away from F. excelsior to early successional pioneer species such as Alnus incana, Betula spp., and in some instances Populus tremula.

Authors/Creators:Bakys, Remigijus
Title:Dieback of Fraxinus excelsior in the Baltic Sea Region
Subtitle:associated fungi, their pathogenicity and implications for silviculture
Series Name/Journal:Acta Universitatis Agriculturae Sueciae
Year of publishing :23 January 2013
Number of Pages:48
I.Bakys, R., Vasaitis, R., Barklund, P., Thomsen, I. M. & Stenlid, J. (2009). Occurrence and pathogenicity of fungi in necrotic and non-symptomatic shoots of declining common ash (Fraxinus excelsior) in Sweden. European Journal of Forest Research 128, 51-60.
II.Bakys, R., Vasaitis, R., Barklund, P., Ihrmark, K. & Stenlid, J. (2009). Investigations concerning the role of Chalara fraxinea in declining Fraxinus excelsior. Plant Pathology 58, 284-292.
III.Bakys, R., Vasiliauskas, A., Ihrmark, K., Stenlid, J., Menkis, A. & Vasaitis, R. (2011) Root rot, associated fungi and their impact on health condition of declining Fraxinus excelsior stands in Lithuania. Scandinavian Journal of Forest Research 26, 128-135.
IV.Bakys, R., Vasaitis, R. & Skovsgaard, J. P. Patterns and severity of crown dieback in young even-aged stands of European ash (Fraxinus excelsior L.) in relation to stand density, bud flushing phenotype and season. Plant Protection Science (in press).
V.Lygis, V., Bakys, R., Gustienė, A., Burokienė, D., Matelis, A. & Vasaitis, R. Forest self-regeneration following clear-felling of dieback-affected Fraxinus excelsior: focus on ash (submitted manuscript).
Place of Publication:Uppsala
Publisher:Dept. of Forest Mycology and Plant Pathology, Swedish University of Agricultural Sciences
ISBN for printed version:978-91-576-7767-9
Publication Type:Doctoral thesis
Full Text Status:Public
Agris subject categories.:H Protection of plants and stored products > H20 Plant diseases
K Forestry > K10 Forestry production
Subjects:(A) Swedish standard research categories 2011 > 4 Agricultural Sciences > 401 Agricultural, Forestry and Fisheries > Forest Science
Agrovoc terms:fraxinus excelsior, forest trees, dieback, forest decline, chalara, armillaria, pathogenicity, root rots, natural succession, lithuania, denmark, sweden
Keywords:Armillaria spp., Hymenoscyphus pseudoalbidus, Fraxinus excelsior, pathogenicity, regeneration, succession, wood-inhabiting fungi
Permanent URL:
ID Code:9391
Department:(NL, NJ) > Dept. of Forest Mycology and Plant Pathology
(S) > Dept. of Forest Mycology and Plant Pathology
External funders:Nordic Council of Ministers
Deposited By: Remigijus Bakys
Deposited On:23 Jan 2013 06:17
Metadata Last Modified:02 Dec 2014 10:54

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