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Biology of Chalara fraxinea: identification and reporting of infected trees
 

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. ...

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 Biology of Chalara fraxinea: identification and reporting of infected trees Presentation Transcript

    • 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
    • Outline • Introduction • Biology of Chalara fraxinea – now correctly called Hymenoscyphus fraxineus • Identification (picture guide) • Reporting (potentially) infected trees • Questions and Discussion
    • 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
    • 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
    • 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 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
    • 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
    • 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
    • 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
    • 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 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
    • 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
    • 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
    • Ancient woodlands and trees in Borrowdale, Cumbria Recognising ash as an important component in many woodland types Photo: E. R. Wilson 2012
    • Ash pollard Near Glaramara, Borrowdale, CumbriaPhoto: E.R. Wilson 2012 Ash in the landscape outside woodlands Important ecological and cultural values
    • 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, 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
    • 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 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
    • 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 once leaves start to expand.
    • 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
    • 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
    • Source: Forestry Commission Wilting leaves from early summer onwards Fruiting bodies on rachis of decaying leaves Signs of disease
    • Signs of disease Source: Barnaby Wylder, Forestry Commission 2012Source: Forest Research Diamond-shaped lesions at branch unions Rapid dieback of branches and stems
    • 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
    • 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
    • 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
    • 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
    • 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.
    • 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
    • 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
    • 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
    • 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
    • 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
    • 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
    • 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
    • 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 caused by the eriophyid mite Aceria fraxinivora. Source: OPAL
    • Nectria canker is caused by the fungus Neonectria galligena. Emerald Ash Borer (Agrilus planipennis) is currently NOT present in UK. Source: OPAL
    • 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
    • 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.
    • 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
    • Photo: E. R. Wilson 2013 Citizen Science – a group of ash tree surveyors at a training event in Eden District, Cumbria, 5 October 2013
    • 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
    • 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 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