Department of Geosciences and Natural Resource Management

Infomeeting Essentaksterfte, Haren, NL 14 april 2015

Experiences of ashdieback 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 (schimmelziekte).But does it kill the ash trees ?

Chalara fraxinea

Hymenoscyphus pseudoalbidus

= Hymenoscyphus fraxineus

Life cycle of the fungus (schimmel)

- A sign of desperation

Noodgroei

High risk of wooddiscolouration

Department of Geosciences and Natural Resource Management

Epicomic shoots on branches and stems

NL Febr. 2015

Department of Geosciences and Natural Resource Management

Sted og datoDias 7

Necroses of bark and wooddiscolouration

Department of Geosciences and Natural Resource Management

Department of Geosciences and Natural Resource Management

Hymenoscyphus fraxineus Origin: Asia on Fraxinus mandschurica

Ref: McKinney et al (2014)

How

?

Amongst the first to die are pendulate ashTreuressen

Department of Geosciences and Natural Resource Management

Sted og datoDias 9

Amongst the first to die are pendulate ashTreuressen

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

Department of Geosciences and Natural Resource Management

2007 2009 2011

2013 Sommer 2013 Winter

See also

slides at the

end

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 AlleeKeine SymptomeTriebe gesundMarts 2014

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

Department of Geosciences and Natural Resource Management

• Viele junge Eschen sterben wahrscheinlich.

• Many young ash trees will probably die.

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

Department of Geosciences and Natural Resource Management

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

2013

Saved at the last minute

This huge ash tree in a churchyard was scheduled for fellingin 2013 due to ash dieback. Instead they did a crownpruning 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 safetyconcerns from dead branches.

Department of Geosciences and Natural Resource Management

2014

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,

oder 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.

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

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

Conclusions

• Please do not panic !

• It is not like Dutch Elm disease, felling treesfast 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 Fraxinusamericana / pennsylvanica or even Fraxinusmandschurica.

• .

Department of Geosciences and Natural Resource Management

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

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2012

IMT, University of Copenhagen

2013

IMT, University of Copenhagen

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2013

IMT, University of Copenhagen

2014

IMT, University of Copenhagen