Tree Disease and Biosecurity Challenges. Joan Webber, Principal Pathologist Tree Health Forestry & Climate Change Centre

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1 Tree Disease and Biosecurity Challenges Joan Webber, Principal Pathologist Tree Health Forestry & Climate Change Centre Tree Disease Risks Seminar: Portcullis House, London 28 th Nov 2012

2 Defra-FC Tree Health Action Plan Arrival of damaging pests and pathogens in Britain

3 New tree disease outbreaks UK Chalara fraxinea: Ash Cryphonectria parasitica: Sweet chestnut Phytophthora austrocedrae: Native juniper Phytophthora lateralis: Lawson cypress Acute oak decline: Native oaks Phytophthora ramorum: Larch Phytophthora pseudosyringae: Native heath, Nothofagus Phytophthora kernoviae: Native heath Phytophthora pseudosyringae: Beech, hornbeam Pseudomonas syringae pv aesculi: Horse chestnut Phytophthora kernoviae: Beech, rhododendron etc Phytophthora ramorum: Rhododendron, beech Dothistroma septosporum: Pines Ophiostoma novo-ulmi: Elm Phytophthora alni: Alder

4 New tree pest outbreaks UK Asian Longhorn beetle. Broadleaves Cryphonectria parasitica. Sweet chestnut Phytophthora austrocedrae. Native juniper Phytophthora lateralis. Lawson s cypress Phytophthora ramorum. Larch Phytophthora pseudosyringae. Native heath, Nothofagus Pine-tree Lappet moth Phytophthora kernoviae. Native heath Phytophthora pseudosyringae. Oak processionary Beech, hornbeam moth Pseudomonas syringae pv aesculi. Horse chestnut Phytophthora kernoviae. Beech, Horse rhododendron chestnut leaf etc miner Phytophthora ramorum. Beech, rhododendron etc Dothistroma septosporum. Gypsy moth Pines Ophiostoma novo-ulmi. Elm Dendroctonus micans. Phytophthora Spruce alni. Alder

5 Pathways for entry Logs bark free, treated Sawn timber heat treated, kiln dried Wood packaging material heat treatment ISPM 15

6 Pathways for entry - plants Known pests/pathogens, intercept via visual inspection Cryptic pathogens and asymptomatic sporulation Phytophthora ramorum Non-host carriers The size issue! instant trees Difficult to treat Commodities/products may not be homogeneous Assumes everything can be inspected EU trading block is only as safe as the weakest MS Not all risk organisms are known

7 Impact of invasives in natural environment vs agricultural systems E Im Impact A Im Years Waage et al x How long is this phase?

8 x A newly arrived organism Fitness traits Selection components? Hybridisation Introgression Sex 2ry introductions Mutation Genetic bottleneck After Brasier, 1987

9 Impact Dothistroma needle blight

10 Impact P ramorum on larch

11 Asian Longhorn Beetle Outbreak in Kent March 2012

12 Ash dieback in Europe Chalara fraxinea Emerged as an entirely new disease in Europe in the 1990s, but causal agent (Chalara fraxinea) only named in 2006 Confusingly also known as Hymenoscyphus pseudoalbidus Has close relative Hymenoscyphus albidus - probably a native in Europe & harmless to ash Early impact Poland, Lithuania, then Scandinavian countries Some countries 60-90% ash affected eg Denmark Disease has spread to most EU MS, apart from far west & south Despite impact & spread not designated as quarantine organism

13 Ash dieback disease Chalara fraxinea

14 Ash dieback disease H. pseudoalbidus fruit bodies on fallen ash rachises Photos courtesy of Thomas Kirisits.

15 Arrival in GB First finding March 2012 in a nursery trees imported from Netherlands Next finding in May trees planted winter 2011/12 in a car park near Leicester ~ 500 trees planted About half symptomatic Home grown, UK seed source Trade lack of awareness about the risk from Chalara fraxinea Chalara spores: Photo courtesy of Ogris et al. (2009) Plants also distributed to around 40 other locations Since then, other nursery findings, but also confirmed outbreak in Scotland (woodland planting 3+ years ago)

16 Action in GB Major survey in November to establish position FC conducted survey with support from FR, Fera, the EA and Natural England In addition, observations for CLA and Woodland Trust members are coming in Survey started 2nd November, with FC teams visiting more than 10,000 sites across GB

17 Confirmed infection sites >120 in wider environment 93 recently planted sites 17 nurseries (not shown) 237 Total Further sites under suspicion Findings Positives mainly in Kent, Norfolk and Suffolk Further west into Berkshire, Sussex and Bedfordshire Further north along the East Coast into Hull, Middlesborough and Northumberland

18 Chalara disease familiar scenario A new disease caused by a fungus (Chalara fraxinea), previously unknown to science Likely origin in east Asia Japan and Korea, where it appears to be harmless European ash susceptible, some resistant individuals Long distance: plant trade pathway? Local spread: wind borne spores, up to 20-30km /year A changing organism, possibility of hybridisation genetic exchange with resident Hymenoscyphus albidus Emerald Ash Borer hugely damaging in USA

19 Acknowledgements Forest Research, Centre for Forestry & Climate Change Anna Brown (Dothistoma needle blight): Alice Holt Sandra Denman (oak decline): Alice Holt Anna Harris, Gavin Hunter (Phytophthora ramorum): Alice Holt Nigel Straw, Dave Williams (OPM, horse chestnut leaf miner, ALB): Alice Holt Sarah Green (horse chestnut bleeding canker); NRS Roger Moore (Pine-tree Lappet Moth): NRS Pest & Disease Diagnostic Advisory Service Christine Tilbury, David Rose, Steven Hendry