LAP Ash Dieback Workshop
The biology of Chalara fraxinea:
identification and reporting of infected trees
Edward Wilson
Sil...
Outline
• Introduction
• Biology of Chalara fraxinea
– now correctly called Hymenoscyphus fraxineus
• Identification (pict...
Threats to UK Forests
Source: Forestry Commission England 2012
• Climate change
– Summer droughts increasingly likely, esp...
25th July 2012
Which tree species to plant for a changing
environment
Biosecurity of Trees in Britain: Ash dieback disease...
2010 2011
2005
20062002
2009
2003
2002
2011
2012
2012
Decade of Contagion?
Source: Barnaby Wylder 2013
History of Chalara fraxinea
Date Event/Comment
1992 New lethal disease of ash observed in Poland
1992 - Spread to other re...
Ash dieback disease – Chalara fraxinea
Natural range of ash (Fraxinus excelsior) in Europe
Dates indicate the spread of in...
Ash dieback in Europe – Chalara fraxinea
 Vascular wilt fungus
 Pleomorphic (two stage life cycle)
 Emerged as an entir...
There appears to be variation among Fraxinus spp.
in resistance or tolerance to Chalara fraxinea
Highly susceptible
Fraxin...
Source: Barnaby Wylder, Forestry Commission 2012
Ash Dieback in Denmark
Photo: Mari Jonsson,
Swedish University of Agricultural Sciences
Ash Dieback in Sweden
Ash Dieback Disease
(Chalara fraxinea)
• February 2012
– consignment of seedlings
from Netherlands to the
UK found to be i...
Ash Dieback Disease
(Chalara fraxinea)
• November 2012 –
– Cobra Committee Meets
– National Survey
– Recognition of 2 poss...
Ash in the UK
Source: Forestry Commission 2013
Ash in the UK:
• 142K Ha
• 11 % of broadleaves
• 14 % of standing
broadleaf...
Ancient woodlands and trees in Borrowdale, Cumbria
Recognising ash as an important component in many woodland types
Photo:...
Ash pollard
Near Glaramara, Borrowdale, CumbriaPhoto: E.R. Wilson 2012
Ash in the landscape outside woodlands
Important ec...
Ash pollard
Near Rosthwaite, Borrowdale, Cumbria Photo: E.R. Wilson 2012
Review of Ecological Implications
of Chalara ash dieback in Britain (2014)
• 953 species “associated” with ash:
– 12 birds...
Ash Dieback Locations
6 November 2012
Source: Forestry Commission
Wider Environment
Newly Planted/Nurseries
Source: Forestry Commission
Ash Dieback Locations
22 November 2012
Wider Environment
Newly Planted/Nurseries
Source: Forestry Commission
Ash Dieback Locations
28 May 2013
Wider Environment
Newly Planted/Nurseries
Source: Forestry Commission
Ash Dieback Locations
11 November 2013
Wider Environment
Newly Planted/Nurseries
Source: Forestry Commission
Ash Dieback Locations
16 June 2014
Wider Environment
Newly Planted/Nurseries
0
100
200
300
400
500
600
700
0 50 100 150 200 250 300 350 400 450 500 550 600
Reports
Days from Start of Outbreak
Nursery...
Anatomy of an ash leaf
Compund leaf
Leaflet
Blade
Midrib
Rachis
Petiolule
Petiole
Photo: E. R. Wilson 2013
Photo: E. R. Wilson 2013
Ash is famously late flushing in
spring. However, infection can
occur very early in the season
on...
Ash dieback – a foliar disease
Images courtesy of I Thomsen and L McKinney
Image Stina Bengtsson
Lifecycle of Chalara frax...
Spore release of Hymenoscyphus fraxineus
Spore numbers at night Spore numbers at 5am Spore numbers at 7am
Work of Halvor S...
Source: Forestry Commission
Wilting leaves from early summer onwards Fruiting bodies on rachis of decaying leaves
Signs of...
Signs of disease
Source: Barnaby Wylder, Forestry Commission 2012Source: Forest Research
Diamond-shaped lesions at branch ...
Trace Forward: Recently planted seedling showing
signs of ash dieback disease (Chalara fraxinea).
Note 1. dieback on shoot...
Recently planted ash seedlings showing signs of ash
dieback disease (Chalara fraxinea), Golden Wood, Suffolk
(Green Light ...
Early signs of ash dieback disease (Chalara fraxinea) on young coppice shoots,
Frithy Wood, Suffolk (Green Light Trust). P...
Ascocarps (fruiting bodies) on the rachis of a leaf from the 2013 growing season,
at the base of young coppice shoots, Fri...
Advanced wilting of ash leaves due to ash dieback
disease (Chalara fraxinea). Frithy Wood, Suffolk (Green
Light Trust). Ph...
Dieback on shoots (2013) and wilting leaves (2014), signs of ash dieback disease
(Chalara fraxinea), Frithy Wood, Lawshall...
Dieback on shoots (2013) and wilting leaves (2014), signs of ash dieback disease (Chalara
fraxinea), Golden Wood (Green Li...
Dieback on shoots of pole-stage ash. Note the different pattern of dieback on adjacent trees.
Golden Wood (Green Light Tru...
Different patterns of ash dieback on adjacent trees, Frithy Wood (Green Light Trust), Lawshall, Suffolk.
At advanced stage...
Where there are high
spore densities it is
possible to see basal
lesions associated with
direct infection of the
stem.
Les...
Photo: E. R. Wilson 2013
Ash tress by the River Eamont, Cumbria
There are two ash trees in this picture – one bearing seed...
There is often significant variation in flushing dates:
Two veteran ash trees in Cumbria, 19 May 2014
(approximately 200 m...
Dasineura fraxini
the ash midrib gall midge
Photo: E. R. Wilson 2013
Photograph courtesy of Nigel Straw, Forest Research
The ash bud moth Prays
fraxinella, is a native micromoth.
Ash key gall...
Nectria canker is caused by the
fungus Neonectria galligena.
Emerald Ash Borer (Agrilus
planipennis) is currently NOT
pres...
Strategy and Action for Ash
• National Strategy
– Latest update, late March 2013
– Focus on research, monitoring, diagnosi...
Proposed Map of
Important Ash Locations
Silviculture and management
guidance is evolving and will
vary with region and the...
Citizen Science
• A range of projects are underway!
• AshTag – identification/report suspected cases
• First a mobile phon...
Photo: E. R. Wilson 2013
Citizen Science – a group of ash tree surveyors at a
training event in Eden District, Cumbria, 5 ...
Further Information
• Forestry Commission
– www.forestry.gov.uk/chalara
– 08459 33 55 77 (open 8am - 6pm every day)
– plan...
livingashproject.org.uk
Project partners:
Ash pollard
St John’s in the Vale, Cumbria Photo: E.R. Wilson 2012
LAP Ash Dieback Workshop
Acknowledgements
My thanks to the following colleagues: Ben Jones and Barnaby Wylder, Forestry
Co...
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Biology of Chalara fraxinea: identification and reporting of infected trees

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This presentation was prepared for the Living Ash Project Chalara Ash Dieback Workshop at Lawshall, Suffolk on 18 June 2014.

The talk aims to provide an overview of the history and biology of Chalara ash dieback in Britain, and focuses on the lifecycle, signs and symptoms of infection. Additional information is provided regarding current research programmes on ash dieback disease, the genetics of ash (Fraxinus excelsior) and arrangements for reporting suspected cases of infection. The presentation includes many photographs taken in the field and supplied with acknowledgement by colleagues.

Further information on the Living Ash Project is available at www.livingashproject.org.uk. Also at the Future Trees Trust, www.futuretrees.org. General information about the biology of Chalara ash dieback is available from the Forestry Commission, www.forestry.gov.uk/chalara.

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Biology of Chalara fraxinea: identification and reporting of infected trees

  1. 1. LAP Ash Dieback Workshop The biology of Chalara fraxinea: identification and reporting of infected trees Edward Wilson Silviculturist Chalara Ash Dieback Workshop Lawshall Village Hall, Lawshall, Suffolk 18 June 2014 First presented: 18 06 2014 This version: v1.1, 02 07 2014 RESEARCH I N T E R N A T I O N A L
  2. 2. Outline • Introduction • Biology of Chalara fraxinea – now correctly called Hymenoscyphus fraxineus • Identification (picture guide) • Reporting (potentially) infected trees • Questions and Discussion
  3. 3. Threats to UK Forests Source: Forestry Commission England 2012 • Climate change – Summer droughts increasingly likely, especially in South and East – Extreme rain and flooding events are more likely – Ecosystem change – especially ground plants • Pests and diseases – Native and exotic • Low Resilience of Existing Forest Resources – Low number of productive species • England – Conifers > 5 species = 88% of area • England – Broadleaves > 5 species = 72% of area – Monoculture stands are most common
  4. 4. 25th July 2012 Which tree species to plant for a changing environment Biosecurity of Trees in Britain: Ash dieback disease is only the latest on a growing list of nasty pests/pathogens Source: Forestry Commission 2012
  5. 5. 2010 2011 2005 20062002 2009 2003 2002 2011 2012 2012 Decade of Contagion? Source: Barnaby Wylder 2013
  6. 6. History of Chalara fraxinea Date Event/Comment 1992 New lethal disease of ash observed in Poland 1992 - Spread to other regions in Europe; causal agent unclear Early 2000s A Chalara fungus isolated from many infected trees 2006 Asexual state of the fungus identified and named Chalara fraxinea Sexual state thought to be Hymenoscyphus albidus, a wide- spread and previously non-lethal fungus on ash 2010 Molecular research later confirmed the sexual state is a new species, Hymenoscyphus pseudoalbidus May 2014 Revised nomenclature for the fungus has led to new name, Hymenoscyphus fraxineus
  7. 7. Ash dieback disease – Chalara fraxinea Natural range of ash (Fraxinus excelsior) in Europe Dates indicate the spread of infection across Europe, with the earliest cases being confirmed in Poland (1992). Map; EUFORGEN
  8. 8. Ash dieback in Europe – Chalara fraxinea  Vascular wilt fungus  Pleomorphic (two stage life cycle)  Emerged as an entirely new disease in Europe in the 1990s  Initially cause was unknown – frost and drought both implicated in dieback symptoms  Early impact Poland, Lithuania, Latvia, then Scandinavian countries  Some countries 60-90% ash affected eg Denmark since 2009.  Despite impact & spread, not designated as quarantine organism Source: Forestry Commission
  9. 9. There appears to be variation among Fraxinus spp. in resistance or tolerance to Chalara fraxinea Highly susceptible Fraxinus excelsior Fraxinus angustifolia Fraxinus niger Moderately susceptible Fraxinus ornus Fraxinus pennsylvanica Least susceptible Fraxinus americana Fraxinus mandschurica
  10. 10. Source: Barnaby Wylder, Forestry Commission 2012 Ash Dieback in Denmark
  11. 11. Photo: Mari Jonsson, Swedish University of Agricultural Sciences Ash Dieback in Sweden
  12. 12. Ash Dieback Disease (Chalara fraxinea) • February 2012 – consignment of seedlings from Netherlands to the UK found to be infected with Chalara fraxinea • October 2012 – Fera confirmed first cases in “wider environment” – Note: now thought likely that the disease arrived in the UK at an earlier date Photo: Forestry Commission 2012
  13. 13. Ash Dieback Disease (Chalara fraxinea) • November 2012 – – Cobra Committee Meets – National Survey – Recognition of 2 possible routes of disease transfer to the UK: • airborne from western Europe • Importation of infected seedlings – Trace Forward surveys initiated • Disease Categories: – Nursery sites – Recently planted sites – Wider environment, e.g. established woodland Photo: Forestry Commission 2012
  14. 14. Ash in the UK Source: Forestry Commission 2013 Ash in the UK: • 142K Ha • 11 % of broadleaves • 14 % of standing broadleaf volume • Mostly found in mixed stands
  15. 15. Ancient woodlands and trees in Borrowdale, Cumbria Recognising ash as an important component in many woodland types Photo: E. R. Wilson 2012
  16. 16. Ash pollard Near Glaramara, Borrowdale, CumbriaPhoto: E.R. Wilson 2012 Ash in the landscape outside woodlands Important ecological and cultural values
  17. 17. Ash pollard Near Rosthwaite, Borrowdale, Cumbria Photo: E.R. Wilson 2012
  18. 18. Review of Ecological Implications of Chalara ash dieback in Britain (2014) • 953 species “associated” with ash: – 12 birds, 28 mammals, 58 bryophytes, 68 fungi, 239 invertebrates, 548 lichens • 62 species were “highly associated” species • 44 “obligate” species: – 11 fungi, 29 invertebrates, 4 lichen • Reference: – Mitchell, R.J., et al. 2014. Conservation Biology 175: 95-109
  19. 19. Ash Dieback Locations 6 November 2012 Source: Forestry Commission Wider Environment Newly Planted/Nurseries
  20. 20. Source: Forestry Commission Ash Dieback Locations 22 November 2012 Wider Environment Newly Planted/Nurseries
  21. 21. Source: Forestry Commission Ash Dieback Locations 28 May 2013 Wider Environment Newly Planted/Nurseries
  22. 22. Source: Forestry Commission Ash Dieback Locations 11 November 2013 Wider Environment Newly Planted/Nurseries
  23. 23. Source: Forestry Commission Ash Dieback Locations 16 June 2014 Wider Environment Newly Planted/Nurseries
  24. 24. 0 100 200 300 400 500 600 700 0 50 100 150 200 250 300 350 400 450 500 550 600 Reports Days from Start of Outbreak Nursery Sites Recently Planted Sites Wider Environment Total D J F M AN M J J A S O Confirmed reports of ash dieback disease (Chalara fraxinea) in the UK 1 November 2012 to 16 June 2014 Data: Forestry Commission 2012-2014 Graphic: AshStat/Silviculture Research International 2014www.silviculture.org.uk N D J F M A M J
  25. 25. Anatomy of an ash leaf Compund leaf Leaflet Blade Midrib Rachis Petiolule Petiole Photo: E. R. Wilson 2013
  26. 26. Photo: E. R. Wilson 2013 Ash is famously late flushing in spring. However, infection can occur very early in the season once leaves start to expand.
  27. 27. Ash dieback – a foliar disease Images courtesy of I Thomsen and L McKinney Image Stina Bengtsson Lifecycle of Chalara fraxinea (Hymenoscyphus fraxineus) H. fraxineus fruit bodies on fallen ash rachises produce ascospores
  28. 28. Spore release of Hymenoscyphus fraxineus Spore numbers at night Spore numbers at 5am Spore numbers at 7am Work of Halvor Solheim, Volkmar Timmermann & Isabella Berja, Skog og Landskap, Norway Early in the morning peaking between 6-8 am during summer
  29. 29. Source: Forestry Commission Wilting leaves from early summer onwards Fruiting bodies on rachis of decaying leaves Signs of disease
  30. 30. Signs of disease Source: Barnaby Wylder, Forestry Commission 2012Source: Forest Research Diamond-shaped lesions at branch unions Rapid dieback of branches and stems
  31. 31. Trace Forward: Recently planted seedling showing signs of ash dieback disease (Chalara fraxinea). Note 1. dieback on shoots 2. lesions at branch unions 3. epicormic/adventitious shoot development in current year Photo: Sharon Rodhouse 2012
  32. 32. Recently planted ash seedlings showing signs of ash dieback disease (Chalara fraxinea), Golden Wood, Suffolk (Green Light Trust). Photo: E. R. Wilson 17 June 2014
  33. 33. Early signs of ash dieback disease (Chalara fraxinea) on young coppice shoots, Frithy Wood, Suffolk (Green Light Trust). Photo: E. R. Wilson 17 June 2014
  34. 34. Ascocarps (fruiting bodies) on the rachis of a leaf from the 2013 growing season, at the base of young coppice shoots, Frithy Wood, Suffolk (Green Light Trust). Photo: E. R. Wilson 17 June 2014
  35. 35. Advanced wilting of ash leaves due to ash dieback disease (Chalara fraxinea). Frithy Wood, Suffolk (Green Light Trust). Photo: E. R. Wilson 17 June 2014.
  36. 36. Dieback on shoots (2013) and wilting leaves (2014), signs of ash dieback disease (Chalara fraxinea), Frithy Wood, Lawshall, Suffolk. Photo: E. R. Wilson 17 June 2014
  37. 37. Dieback on shoots (2013) and wilting leaves (2014), signs of ash dieback disease (Chalara fraxinea), Golden Wood (Green Light Trust), Lawshall, Suffolk. Photo: E. R. Wilson 17 June 2014
  38. 38. Dieback on shoots of pole-stage ash. Note the different pattern of dieback on adjacent trees. Golden Wood (Green Light Trust), Lawshall, Suffolk. Photo: E. R. Wilson 17 June 2014
  39. 39. Different patterns of ash dieback on adjacent trees, Frithy Wood (Green Light Trust), Lawshall, Suffolk. At advanced stages of infection trees often succumb due to secondary pathogens, especially honey fungus (Armillaria spp.). Photo: E. R. Wilson 17 June 2014
  40. 40. Where there are high spore densities it is possible to see basal lesions associated with direct infection of the stem. Lesions due to Chalara fraxinea on the stem of pole-stage ash Photo: J. Clark 2014
  41. 41. Photo: E. R. Wilson 2013 Ash tress by the River Eamont, Cumbria There are two ash trees in this picture – one bearing seed (Tree 1) and the other not (Tree 2). Remember ash keys (samaras) are borne in clusters through winter and should not be confused with signs of dieback. Tree 1 Tree 2
  42. 42. There is often significant variation in flushing dates: Two veteran ash trees in Cumbria, 19 May 2014 (approximately 200 m apart) Photos: E. R. Wilson 2014
  43. 43. Dasineura fraxini the ash midrib gall midge Photo: E. R. Wilson 2013
  44. 44. Photograph courtesy of Nigel Straw, Forest Research The ash bud moth Prays fraxinella, is a native micromoth. Ash key gall caused by the eriophyid mite Aceria fraxinivora. Source: OPAL
  45. 45. Nectria canker is caused by the fungus Neonectria galligena. Emerald Ash Borer (Agrilus planipennis) is currently NOT present in UK. Source: OPAL
  46. 46. Strategy and Action for Ash • National Strategy – Latest update, late March 2013 – Focus on research, monitoring, diagnosis – Regulations and international partnerships – Still gather science information/exploring options for management/containment • E.g., Living Ash Project – Encourage local action • Community Action and Citizen Science – Range of programmes being developed
  47. 47. Proposed Map of Important Ash Locations Silviculture and management guidance is evolving and will vary with region and the prevalence of infected stands. Source: Interim Chalara Control Plan Defra 2012 Areas with widespread Chalara infection and where the disease is established in the wider environment.
  48. 48. Citizen Science • A range of projects are underway! • AshTag – identification/report suspected cases • First a mobile phone app • Re-launched as a tree tagging project for mapping and long-term monitoring • University of East Anglia • OPAL - Tree Buddy Initiative • Sponsored by Forest Research • www.opalexplorenature.org • Treezilla – map of British trees/ecosystem benefits • Open University • www.treezilla.org • Launch 14 June 2013 • Other projects • Woodland Trust • Tree Council • Local Wildlife Trusts
  49. 49. Photo: E. R. Wilson 2013 Citizen Science – a group of ash tree surveyors at a training event in Eden District, Cumbria, 5 October 2013
  50. 50. Further Information • Forestry Commission – www.forestry.gov.uk/chalara – 08459 33 55 77 (open 8am - 6pm every day) – plant.health@forestry.gsi.gov.uk • Food and Environment Research Agency (FERA) – www.fera.defra.gov.uk • TreeWatch - Sylva Foundation – www.sylva.org.uk/treewatch • OPAL – Tree Health Survey – http://www.opalexplorenature.org/TreeSurvey • AshTag – http://ashtag.org/ • Future Trees Trust – www.futuretrees.org
  51. 51. livingashproject.org.uk Project partners:
  52. 52. Ash pollard St John’s in the Vale, Cumbria Photo: E.R. Wilson 2012
  53. 53. LAP Ash Dieback Workshop Acknowledgements My thanks to the following colleagues: Ben Jones and Barnaby Wylder, Forestry Commission England; Joan Webber, Forest Research; Kate Holl, Scottish Natural Heritage; Mari Jonsson, Swedish University of Agricultural Sciences; Tom Brown, Green Light Trust; Jo Clark, Earth Trust; Sharon Rodhouse, Sylvatic Ltd Further Information Edward Wilson Email: ted.wilson@silviculture.org.uk Web: www.silviculture.org.uk First presented: 18 06 2014 This version: v1.1, 02 07 2014 RESEARCH I N T E R N A T I O N A L
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