Emerging Potato Pests? Something old Something new Something borrowed

Transcription

1 Emerging Potato Pests? Something old Something new Something borrowed Colin Jeffries Science and Advice for Scottish Agriculture

2 Outline Potato pests and regulation Something old Potato virus Y (PVY) Clavibacter michiganensis ssp sepedonicus Ralstonia solanacearum Something new Epitrix spp affecting potato tubers Something borrowed Zebra chip disease Pospiviroids

3 Origin of potato pests Mexican gene pool 1590s Potatoes + their pests 1570s Pests of other plant species also pose a risk to potato when those species are grown in association with potato Andean gene pool Andean potato market Images: CIP

4 Pests naturally affecting potato Viroid 1 Viruses 40+ Bacteria 40+ Fungi 50+ Nematodes 10+ Insects 100+ Trade in potatoes especially seed potatoes is heavily regulated because of the risk of introducing new pests into new areas

5 EU Member States The Plant Health Directive SASA 2000/29/EC Prohibits the entry of potatoes for planting from 3 rd countries Entry through quarantine eg UK Potato Quarantine Unit, SASA

6 Something old

7 Potato virus Y (PVY): A changing population Transmitted by aphids (40 species: resident and vagrant) Non-persistent: brief leaf probing lasting a few seconds to minutes required for acquisition- transmission Aphicides are mostly not effective in controlling PVY spread Metopolophium dirhodum (rose grain aphid) Severe mosaic PVY O

8 All change for PVY PVY PVY O PVY N PVY C s Necros das nervuras" (vein necrosis) virus isolated from a Peruvian potato variety growing in Brazil Similar to PVY but caused vein necrosis in tobacco In Europe first detected in a gene bank of South American potatoes grown in England Detected elsewhere in Europe Found in England & Scotland vein necrosis in tobacco Important (epidemics) in the seed producing areas of Netherlands and Germany, 1950s -1970s Less important in other countries eg France, UK LATENT INFECTION IN MOST VARIETIES (low temp)

9 March of PVY N and the recombinants PVY PVY O PVY N PVY C PVY NTN PVY N-Wilga and many more variants world wide PVY O PVY N Non recombinants PVY NTN PVY N-Wilga Recombinants

10 Potato Tuber Necrotic Ringspot Disease (PTNRD) Hungary 1982 Also reported from South America

11 Factors affecting PTNRD development PVY isolates Potato variety Environment High Risk EU-NTN NA-NTN N-Wilga N Nadine Igor Hermes Yukon Gold Nicola Desiree Bintje Spunta 20 C PVY isolate PTNRD Potato variety Environment Low Risk O Maris Piper 10 C - 15 C Slide: C Lacomme

12 PVY N recombinants: A selective advantage over non-recombinants? Aphid virus related More efficiently transmitted by aphid spp? PVY NTN-NA 26% PVY O 8% Longer retention time by the aphid after aquisition - transmitted greater distances? PVY NTN-EU 66% DV71 DV76 DV69 Plant virus related Transmitted earlier or later? Avoids mature plant resistance? Better replication in the plant and translocation to the progeny tubers? Increased fitness (out competes)? More susceptible varieties Mild symptoms in more potato varieties difficult to identify and rogue Field transmission experiment Maris Piper (% plants infected at end of season) starting with same level of inoculum for each virus PVY N found in twice as many varieties as PVY o

13 and R & D Aphids and virus transmission in seed crops ( ) PCL R428 JHI-FERA-SASA-SA-SAC-BioSS Biodiversity, pathogenicity and epidemiology of PVY N field isolates ( ) PCL SASA PhD studentship Evaluating the effectiveness of mineral oils in minimising the spread of non persistent viruses in potato seed crops in GB ( ) PCL R449 SA-NIAB-SASA-SAC-BioSS

14 Brown rot and ring rot Brown rot (Ralstonia solanacearum) EU Quarantine organism Causes wilts and vascular rots of tubers Image:CIP Spread by infected tubers and infested irrigation water Image:CIP Ring rot (Clavibacter michiganensis subsp sepedonicus)) EU Quarantine organism Causes wilts, leaf curl, chlorosis and vascular rots of tubers Spread by infected tubers and contaminated equipment/transport Image:fera Image:S de Boer

15 EU Brown rot / Ring rot survey Seed/ ware Less PL and RO Brown rot positive lots (%) Seed Ware 4 (0006) 35 (0122) 7 (0011) 40 (0133) 11 (0019) 19 (0070) 6 (0009) 35 (0141) 3 (0005) 28 (0121) Ring rot positive lots (%) Seed Ware 75 (011) 2502 (800) 94 (015) 2135 (651) 77 (012) 1701 (548) 51 (008) 1222 (450) 47 (007) 1156 (474) 19 (001) 106 (044)

16 EU Brown rot / Ring rot survey Brown rot positive lots (%) Ring rot positive lots (%) Seed/ ware Seed Ware No Seed brown 75 rot 94 since (seed 51 from non-uk 47 source) 19 (011) (015) (012) (008) (007) (001) Ware (0006) 35 (0122) 2502 (800) (0011) 40 (0133) 2135 (651) (0019) UK 19 (0070) 1701 (548) (0009) 35 (0141) 1222 (450) (0005) 28 (0121) No ring rot since 2006 (seed from non-uk source) 1156 (474) 2010 Less PL and RO 106 (044)

17 Something new

18 Epitrix spp (flea beetles) damaging to potato tubers E cucumeris E similaris E subcrinita E tuberis Currently not EU quarantine pests Epitrix similaris Epitrix cucumeris

19 Epitrix life cycle Yield reductions 15% for E cucumeris E tuberis larva feeding holes up to 1cm deep Adult E cucumeris, E similaris, E subcrinita more superficial Egg Larva Pupa Up to 3 generations per year in Portugal Images: fera

20 Geographical distribution and risk of establishment in the EU Epitrix spp World distribution EU current distribution EU at risk E cucumeris Americas (North, Central, South) Portugal 2004 (+ Azores 1979) Most E similaris N America (California) Portugal 2004, Spain 2008 At least the Mediterranean basin E subcrinita N America, S America (Peru) absent All E tuberis N America absent All Major uncertainties: accuracy of distribution records identification to species After EPPO PRA

21 Pathways Major Potato tubers for planting, consumption or processing with soil or plant debris Lesser Soil attached to plants for planting: host plants (eg tomato aubergine) non host plants Soil attached to machinery Natural movement of Epitrix

22 Pathways Major Potato tubers for planting, consumption or processing with soil or plant debris Lesser If Epitrix established in the UK it would be impossible to eradicate Soil attached to plants for planting: Soil attached to machinery Natural movement of Epitrix host plants (eg tomato aubergine) Cost to the potato non host industry plants 10m - 41m (4% -16% reduction in gross margin) figures from fera

23 Action plan 2010 onwards UK Stakeholder consultation Voluntary notification of imports from Spain and Portugal (seed or ware) for 2011 EPPO Pest risk analysis (PRA) for Epitrix spp damaging potato tubers has been completed EU Discussion on introduction of emergency legislation, November 2011 Pest free areas Treatment of potatoes (washing or brushing) in the country of export

24 Something borrowed

25 Zebra chip disease Darkened stripes in potato crisps Mexico 1994 USA 2000 Sporadic losses 2004 onwards USA Losses = $ million + Discolouration of medullary rays Swollen nodes, leaf curl, purple top, wilt, aerial tubers 2006 onwards eastern Europe Losses = $ million onwards New Zealand Losses = $ million+ Symptoms of ZC rarely seen Images: G Secor

26 Bacteria associated with zebra chip Candidatus Liberibacter solanacearum NZ 2008 North America: Mexico (Coahuila, Sinaloa), USA (California, Kansas, Nebraska, Nevada, Texas, Wyoming) Central America: Honduras, Guatemala Ca Phytoplasma solani Europe: Hungary, Romania, Russia Phytoplasmas and Liberibacter Obligate parasites of plant phloem tissue They cannot be cultured in vitro in cell-free media Liberibacter has a cell wall (gram-negative) Phytoplasmas do not have a cell wall Electron microscope images of Ca L solanacearum Images: G Secor

27 Vectors and hosts Ca P solani Ca L solanacearum Psyllid not present in Europe VECTOR Plant/leaf hopper: Hyalesthes obsoletus Reptalus spp VECTOR Psyllid: Bactericera cockerelli (potato/tomato) HOSTS Solanaceous crop plants eg Potato Tomato Others Bindweed Everlasting Pea HOSTS Solanaceous crop plants eg Potato Tomato Pepper/Chilli Eggplant Cape gooseberry Others Peas? Mallow? Cypressus? Weeds (Polygonaceae/Solanaceae) Hyalesthes obsoletus Bactericera cockerelli

28 CLIMEX: Potential distribution of Bactericera cockerelli Potential distribution based on N America pest data Potential distribution based on New Zealand pest data Source: EPPO

29 Ca L solanacearum: Carrots, Finland 2010 Carrots, celery, Spain 2011 Feeding damage Does not feed on potato Infection with Ca L solanacearum Feeds on potato Carrot psyllids (Trioza apicalis) Images: Anne Nissinen (carrots) Joe Botting (T apicalis) Bactericera trigonica

30 Action plan Post-entry quarantine test introduced for Ca L solanacearum in the UK 2010 EPPO PRA completion soon Earliest approval June 2012 Earliest action by EU late 2012 EU project on Ca L solanacearum (eg survey of carrots, will the carrot Ca L solanacearum infect potato)

31 Pospiviroids A viroid is the smallest known self replicating genetic unit 5-10 x smaller than a virus Viroid structure Transmission: vegetative seed mechanically /contact aphids? Potato spindle tuber viroid (PSTVd) (genus Pospiviroid) The first named viroid Also a major pathogen of tomato EU quarantine organism Electron microscope image of denatured viroid RNA Scale line =1000 A

32 PSTVd infection of potato 3rd generation Preventing entry of PSTVd in potato has been well controlled by quarantine measures Healthy (Prohibition / post entry quarantine) 1 st generation 3 rd generation Norgold Russet Images: S Slack La Chipper

33 PSTVd outbreaks in tomato crops PSTVd in tomato not so well controlled by current EU measures (seed from areas where PSTVd is not known to occur or absence of symptoms or sample testing where PSTVd is known to occur) The Netherlands The Netherlands Denmark England Belgium Italy England

34 PSTVd infects solanaceous ornamentals Plants of Solanaceae (other than seeds) prohibited except from Europe and Mediterranean countries Species Year of publication Brugmansia spp Calibrachoa spp 2010 unpublished Brugmansia Solanum jasminoides Datura spp 2010 Lycianthes rantonnetii 2007 Petunia spp 2009 Solanum jasminoides 2008 Solanum jamesonii 2008 Calibrachoa Lycianthes rantonnetii

35 Samples positive for PSTVd in EU: domestic production survey Year Positive samples: total (% ) 376 (43) 164 (17) 219 (16) 165 (12) Positive samples: Solanum jasminoides (%) 294 (33) 132 (20) 154 (14) 146 (17) 2010 Internal movement 47 S jasminoides 5 Brugmansia 2 Petunia 1 Lycianthes rantonnetii Commission decision 2007/410/EC on measures to prevent the introduction into and the spread within the Community of Potato spindle tuber viroid

36 Other pospiviroids infect potato experimentally EU quarantine pest in chrysanthemum Chrysanthemum stunt viroid Tomato chlorotic dwarf viroid Healthy Healthy Non-EU quarantine pest Citrus exocortis viroid Columnea latent viroid Pepper chat fruit viroid Tomato apical stunt viroid Tomato chlorotic dwarf viroid Tomato planta macho viroid EstimaPSTVD: Potato Citrus exocortis viroid Healthy PSTVD: Pentland TomatoDell Columnea latent viroid Healthy Images of tubers: JTh Verhoeven

37 Pospiviroids infect ornamental plants Chrysanthemum stunt viroid Chrysanthemum x morifolium Dahlia spp Petunia spp Solanum jasminoides Verbena spp Solanaceae Citrus exocortis viroid Impatiens spp Solanum jasminoides Verbena spp Columnea latent viroid Brunfelsia undulata Tomato apical stunt viroid Tomato chlorotic dwarf viroid Gloxinia spp Nematantus wettsteinii Cestrum spp Lycianthes rantonnetii Solanum jasminoides Solanum jamesonii Brugmansia sanguinea Petunia hybrida Pittosporum tobira Verbena spp Detected in UK in 2007 and 2010 In Scotland plants destroyed under EU Plant Health Directive emergency measures (Article 162) However, measures vary between member states

38 2011 EFSA scientific opinion of the risk of solanaceous pospviroids All pospiviroids are infectious to potato and to tomato and therefore present a similar threat as PSTVd to both crops PATHWAYS IDENTIFIED (Major: true seed, seed potato tubers, plants for planting) Minor: plants not intended for planting ESTABLISHMENT High SPREAD Likely PATHWAY TO POTATO Unlikely but with high uncertainty

39 2011 EFSA scientific opinion of the risk of solanaceous pospviroids All pospiviroids are infectious to potato and to tomato and therefore present a similar threat as PSTVd to both crops PATHWAYS IDENTIFIED (Major: true seed, seed potato tubers, plants for planting) Minor: plants not intended for management planting ESTABLISHMENT High EU to decide on options SPREAD Likely PATHWAY TO POTATO Unlikely but with high uncertainty

40 Minimise your risk Choose your seed with care