Department of Geosciences and Natural Resource Management
Experiences of ash dieback in Denmark Senior adviser Iben Margrete Thomsen Department of Geosciences and Natural Ressource Management University of Copenhagen
Infomeeting Essentaksterfte, Haren, NL 14 april 2015
Department of Geosciences and Natural Resource Management
Essentaksterfte / Ash Dieback
Ash dieback is a fungal disease (schimmelziekte). But does it kill the ash trees ?
Life cycle of the fungus (schimmel) Chalara fraxinea Hymenoscyphus pseudoalbidus = Hymenoscyphus fraxineus
Department of Geosciences and Natural Resource Management
Noodgroei
- A sign of desperation
High risk of wood discolouration
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Epicomic shoots on branches and stems
NL Febr. 2015
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Necroses of bark and wood discolouration
Sted og dato Dias 7
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Hymenoscyphus fraxineus Origin: Asia on Fraxinus mandschurica
How ?
Ref: McKinney et al (2014)
Department of Geosciences and Natural Resource Management
Amongst the first to die are pendulate ash Treuressen
Sted og dato Dias 9
Department of Geosciences and Natural Resource Management
Amongst the first to die are pendulate ash Treuressen
Department of Geosciences and Natural Resource Management
Essentaksterfte / Ash Dieback
Katastrofal im Wald / A disaster in forests In der Stadt /offenen Landschaft weniger fatal Less fatal in towns and the open landscape
Department of Geosciences and Natural Resource Management
2007
2009
2011 See also slides at the end
2013 Sommer
2013 Winter
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Fraxinus in Kopenhagen 1.400 Strassenbäume 8% des Bestands Überwiegend F. excelsior 50 % später als 2000 gepflanzt Nicht seit 2012 F. excelsior Allee Keine Symptome Triebe gesund Marts 2014
Department of Geosciences and Natural Resource Management
Possible explanations • No honey fungus / honingzwam (Armillaria) • No ash bark beetles / Essenbastkever (Hylesinus)
Department of Geosciences and Natural Resource Management
Reduzierte Infektion / Reduced infection • Laubentfernung / removal of leaf litter • Eher Trocken = weniger Fruchtkörper • Drier conditions = fewer fruitbodies
Department of Geosciences and Natural Resource Management
Stadt- und Straßenbäumen / City and road trees • Viele junge Eschen sterben wahrscheinlich. • Many young ash trees will probably die.
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Stadt- und Straßenbäumen / City and road trees
• Alte Eschen sterben manchmal auch. • Old ash trees die occasionally.
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Aber viele alte Esche 端berleben
But plenty of old ash trees survive
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2013
Ash dieback outside of forests is an aesthetical problem, not a matter of survival. Stay calm.
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Saved at the last minute
2014
This huge ash tree in a church yard was scheduled for felling in 2013 due to ash dieback. Instead they did a crown pruning and kept the tree. The old ash will probably live for many years with the disease, showing dieback symptoms in some years and less in others. Repeated pruning every 5 or 10 years will deal with any safety concerns from dead branches.
Department of Geosciences and Natural Resource Management
Nicht zu fruh fällen / Don’t fell too soon
Eschen in Städten, längs Straßen und in der Landschaft so lange wie möglich bewahren (Verkehrssicherheit beachten). Preserve ash trees in cities, along road and in the landscape for as long as possible (keep safety in mind).
Department of Geosciences and Natural Resource Management
Die B채ume sollten erst gef채llt werden, wenn sie absterben, oder ihre Krone 체ber 2-3 Jahre nicht wieder regenerieren.
The trees should be felled when they die, or when they do not regenerate their crowns 2-3 years in a row.
Department of Geosciences and Natural Resource Management
Zukunft der Eschen / Future of ash ?
Resistente Eschen anwenden - wenn sie verf端gbar sind. Use resistant species / clones - if or when available
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Find and clone healthy ash
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Test resistance against disease Artificial inoculation with H. fraxineus
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Seed orchard with controlled crossings
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Conclusions • Please do not panic ! • It is not like Dutch Elm disease, felling trees fast does not prevent spread of fungus. • Removing fallen leaves is much better. • Sick trees can live many years and look OK, particularly if you remove dead branches. • 1-2 % ash are resistant, look out for them. • Use Fraxinus ornus or perhaps Fraxinus americana / pennsylvanica or even Fraxinus mandschurica. • .
2007
IMT, University of Copenhagen
2008
IMT, University of Copenhagen
2009
IMT, University of Copenhagen
2010
IMT, University of Copenhagen
2011
IMT, University of Copenhagen
2012
201 1
IMT, University of Copenhagen
2013
IMT, University of Copenhagen
Dec 2013
IMT, University of Copenhagen
2014
IMT, University of Copenhagen