Experiences of ash dieback in Denmark Senior adviser Iben Margrete - - PDF document

21-02-2015 Iben M. Thomsen, University of Copenhagen 1

Department of Geosciences and Natural Resource Management Expertmeeting Essentaksterfte, Drachten, NL 18 februari 2015

Experiences of ash dieback in Denmark

Senior adviser Iben Margrete Thomsen Department of Geosciences and Natural Ressource Management University of Copenhagen

Essentaksterfte / Ash Dieback

Department of Geosciences and Natural Resource Management

Ash dieback is a fungal disease. But does it kill the ash trees ?

21-02-2015 Iben M. Thomsen, University of Copenhagen 2 Chalara fraxinea Hymenoscyphus pseudoalbidus = Hymenoscyphus fraxineus

Life cycle of the fungus

21-02-2015 Iben M. Thomsen, University of Copenhagen 3

• A sign of

desperation

Noodgroei

High risk of wood discolouration

Department of Geosciences and Natural Resource Management

Epicomic shoots on branches and stems

NL Febr. 2015

21-02-2015 Iben M. Thomsen, University of Copenhagen 4

Sted og dato Dias 7

Necroses of bark and wood discolouration

Department of Geosciences and Natural Resource Management

Hymenoscyphus fraxineus Origin: Asia on Fraxinus mandschurica

Ref: McKinney et al (submitted)

How ?

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Amongst the first to die are pendulate ash Treuressen

Department of Geosciences and Natural Resource Management Sted og dato Dias 9

Amongst the first to die are pendulate ash Treuressen

Department of Geosciences and Natural Resource Management

21-02-2015 Iben M. Thomsen, University of Copenhagen 6

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 Department of Geosciences and Natural Resource Management

2007 2009 2011 2013 Sommer 2013 Winter See also slides at the end

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Fraxinus in Kopenhagen

Department of Geosciences and Natural Resource Management

1.400 Strassen- bäume 8% des Bestands Überwiegend F. excelsior 50 % später als 2000 gepflanzt Nicht seit 2012

• F. excelsior Allee

Keine Symptome Triebe gesund Marts 2014

Possible explanations

• No honey fungus / honingzwam (Armillaria)
• No ash bark beetles / Essenbastkever

(Hylesinus)

Department of Geosciences and Natural Resource Management

21-02-2015 Iben M. Thomsen, University of Copenhagen 8

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

Department of Geosciences and Natural Resource Management

• Viele junge Eschen sterben wahrscheinlich.
• Many young ash trees will probably die.

21-02-2015 Iben M. Thomsen, University of Copenhagen 9

Stadt- und Straßenbäumen / City and road trees

Department of Geosciences and Natural Resource Management

• Alte Eschen sterben manchmal auch.
• Old ash trees die occasionally.

Aber viele alte Esche überleben

Department of Geosciences and Natural Resource Management

But plenty of old ash trees survive

21-02-2015 Iben M. Thomsen, University of Copenhagen 10

Department of Geosciences and Natural Resource Management

Ash dieback outside of forests is an aesthetical problem, not a matter of survival.

2013 Saved at the last minute

This huge ash tree in a church yard was scheduled for felling in 2013 du 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

2014

21-02-2015 Iben M. Thomsen, University of Copenhagen 11

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 Bäume sollten erst gefällt werden, wenn sie absterben,

• der ihre Krone über 2-3 Jahre nicht wieder regenerieren.

Department of Geosciences and Natural Resource Management

The trees should be felled when they die, or when they do not regenerate their crowns 2-3 years in a row.

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Zukunft der Eschen / Future of ash ?

Resistente Eschen anwenden

• wenn sie verfügbar sind.

Use resistant species / clones

• if or when available

Department of Geosciences and Natural Resource Management

Find and clone healthy ash

Department of Geosciences and Natural Resource Management

21-02-2015 Iben M. Thomsen, University of Copenhagen 13

Test resistance against disease

Artificial inoculation with

• H. fraxineus

Department of Geosciences and Natural Resource Management

Seed orchard with controlled crossings

Department of Geosciences and Natural Resource Management

21-02-2015 Iben M. Thomsen, University of Copenhagen 14

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 or F. mandschurica.

Department of Geosciences and Natural Resource Management

2007

IMT, University of Copenhagen

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2008

IMT, University of Copenhagen

2009

IMT, University of Copenhagen

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2010

IMT, University of Copenhagen

2011

IMT, University of Copenhagen

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2012

IMT, University of Copenhagen

2013

IMT, University of Copenhagen

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Dec 2013

IMT, University of Copenhagen

2014

IMT, University of Copenhagen