sdu faculty of forestry journal special edition 2009 - Orman Fakültesi

SDÜ ORMAN FAKÜLTESİ DERGİSİ
Transfer of infection nor vector has not been clarified till now. One can assume
that infection occurs via ascospores of H. albidus which are formed on leaf fall of
ash during summer months. It corresponds to time period of development of newly
attacking infection. Rapid and especially sudden dissemination of this disease
throughout Europe is not typical for tree disease, is it more typical for non biotic
diseases or for insect outbreaks. Especially an area, which is being occupied during
relatively short period of time, is enormous. For pathogens, it is difficult to
penetrate structural suberin barrier which is represented by unharmed bark. The
influence of sucking insect can be discussed. Remarkable is the fact that lesions
occur practically at the same place like the colony of woolly aphids Prociphilus
spp. Aphid`s colonies are located on shoots and petioles of leaves. In nurseries,
where chemical control against sucking insect was applied, symptoms of ash
dieback disappeared. Woolly aphids are not reported to occur in all areas where ash
decline was observed. Sucking insect can play a role of agent which creates a
defect in the bark. In sucking locations, tissues suffer from necrosis and fungi like
C. fraxinea penetrate through the tissues. There is an apparent separation of reason
– sucking of aphids during spring time and formation of necrosis during summer
time when the connection to sucking insect needs not to be evident.
4. CONCLUSION
The bionomy of the fungus, infection cycle, pathology, resp. pathogenicity of
the fungus and genetic structure are main topics of contemporary research.
Although pathogenicity of the C. fraxinea has been proved, the mechanism of
penetration of fungus into host is not known yet. The role of sucking insect, mainly
woolly aphids, should be crucial due to production of lesion around sucking points
at the position of previous aphid colonies. The relationship of sucking insects and
C.fraxinea in ash dieback pathology requires further investigations.
5. ACKNOWLEDGEMENTS
This project was supported by MSM 6215648902 and Grant foundation of
FFWT MUAF.
6. REFERENCES
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Cech, T., Hoyer-Tomiczek, U., 2007. Aktuelle Situation des Zurücksterbens der Esche in Österreich.
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EPPO, 2007. Ash dieback in Europe and possible implication of Chalara fraxinea: addition to the
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EPPO, 2008a. First report of Chalara fraxinea in Norway. EPPO Reporting service 2008/181.
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