Distribution, Character, and Management of Late Blight in Recent Years

Transcription

1 Distribution, Character, and Management of Late Blight in Recent Years Amanda J. Gevens Dept. of Plant Pathology, Univ. of Wisconsin-Madison August 25, 2014 Late Blight Q&A Meeting Hancock Agricultural Research Station 4:00-6:00PM

2 Late blight Organism: Phytophthora infestans Overwinters/source: Seed tubers; Cull piles; volunteers; nightshade weeds; movement of spores aerially Infectious spore: Sporangia or zoospores; Rain splash, wind, or mechanical Symptoms: Water-soaked spots; spots grow if weather permits; sporulation (fuzz) occurs at lesion boarders on undersides of leaves Outcome: Complete foliar decline; yield loss; storage loss New predominant genotype/strain also causes disease on tomato

3 Late blight Importance: Very Cost to control or crop loss: Worldwide $6.7 billion annually U.S. $77 million spent on control; despite control, losses are estimated at $288 million annually

4 Phytophthora spore types Sporangia Zoospores Cysts and Mycelial Development Spore drawings courtesy of M.K. Hausbeck, MSU

5 Phytophthora spore types Sporangia Zoospores Cysts and Mycelial Development Spore drawings courtesy of M.K. Hausbeck, MSU

6 Phytophthora spore types Sporangia Zoospores Oospore? Cysts and Mycelial Development Spore drawings courtesy of M.K. Hausbeck, MSU

7 Disease Cycle of Late Blight (Phytophthora infestans) New genotype Optimum temps 60-75F day 50-60F night A1 A2 2 Mating types needed Requires a living host Figure from Smart, Cornell,

8 LB introduced to US from Central America in early 1800 s History of late blight Irish Potato Famine 1970 A2 strains brought to Europe from Central America US (WI) identifies newer strains US-22 (A2), 23 (A1), 24 (A1) in current Current LB in northeastern US prior to 1840 s worldwide distribution of potato and an A1, clonal type, US-1 (clonal descendent of strain that caused Irish Famine) 1990s several aggressive new strains introduced in US (WI) from Mexico (US- 8, A2) Limited movement of potatoes from Mexico prior to 1800 s because maize was primary Central American food crop and cultivated potato was not likely advanced and distributed from ~ in a significant manner

9 Genotypes of P. infestans Genotype/strain is the genetic makeup of an organism Determination of genotype is valuable as associations indicate host preference and resistance to fungicide(s) 24 genotypes have been identified in US (since initial introduction in mid-1800s) Typically US epidemics have just a few genotypes active in a year

10 National Late Blight Research & Extension Collaboration, National Institute of Food & Agriculture - AFRI Coordinated Ag Project Reducing losses to potato and tomato late blight by enhanced monitoring of pathogen populations and improved resistant plants, education, and extension UW-Vegetable Pathology: report disease to website, characterize P. infestans for phenotype, develop decision support system including new rapid techniques for determining mefenoxam sensitivity, evaluate new tomato varieties for resistance, and distribute information in WI for improved disease control Collaborators: Judelson, Fry, Ristaino, Grunewald, Smart, Gevens, Roberts, McGrath, Besley, Xiao, McComas, Klessig, Gloy, Boyles, Girke, Seebold, Johnson, Stone, Gugino, Everts, Scott, Birch, Gay

11 Late Blight Reporting and Information usablight.org

12 U.S. Late Blight Reports 2011-Current

13 U.S. Late Blight Reports 2011-Current Petunia 2% Tomato 50% Potato 50% Tomato 55% Potato 43% Petunia 1% Potato 35% Tomato 64% Potato 43% Tomato 56% Current to 8/24/14

14 Predominant P. infestans clonal lineages in the U.S present Clonal Lineage Mating Type Host (s) Years Found Mefenoxam Sensitivity US-1 A1 potato 1840-present sensitive US-6 A1 potato/tomato* sensitive US-7 A2 potato/tomato* resistant US-8 A2 potato*/tomato 1992-present resistant US-11 A1 potato/tomato 1994-present resistant US-17 A1 tomato 1996 resistant US-18 A2 tomato sensitive US-22 A2 potato/tomato* 2009-present sensitive US-23 A1 potato/tomato* 2010-present sensitive US-24 A1 potato*/tomato 2010-present resistant *= favored host if two hosts are shown Fig. from Halterman & Gevens, Phytophthora infestans in the U.S., book chapter, Phytophthora: A Global Perspective, Edited by K. H. Lamour. CABI published 2013.

15 tomato & potato tomato & potato potato potato tomato & potato tomato (60%) & potato tomato & potato tomato Phytophthora infestans Genotype Incidence in the U.S. in % of all isolates US-23 in Unknown Gentoype New Genotype US-7 Genotype US-8 Genotype US-22 Genotype US-23 Genotype US-23 Variant Genotype US-24 Genotype Data from

16 potato (2 isolates WI) potato & tomato potato potato & tomato (4 isolates NY) 140 Phytophthora infestans Genotype Incidence in the U.S. in 2014 (to Aug 24) 92% of all isolates US-23 in US-8 US-22 US-23 US-24 New Type B 2014

17 Detection of US-22 Genotype 2013 US-22 (mef sens) US-23 (mef sens) US-24 (mef res)

18 Detection of US-23 Genotype 2013 US-22 (mef sens) US-23 (mef sens) US-24 (mef res)

19 Detection of US-24 Genotype 2013 US-22 (mef sens) US-23 (mef sens) US-24 (mef res)

20 Detection of US-8 Genotype 2013 US-7 (mef res) US-8 (mef res) US-24 (mef res)

21 Late Blight Genotypes in Wisconsin in 2014 (24 Aug) County Host(s) Clonal Lineage Portage Potato US-23, US-8 Milwaukee Tomato US-23 Adams Potato US-23?, US-8 Racine Tomato US-23 Waushara Potato US-23?

22 US-23: a successful genotype Simulated epidemics for the US-23 clonal lineage consistently progressed at a higher rate and were more severe than the simulated epidemics of either the US- 22, US-24, or EC-1 clonal lineages US-23 produces more spores on tomato and potato than US-22 or US-24 Results are consistent with the emergence and success of the US-23 lineages observed in WI (and the United States) 2013

23 Phenotypic characterization of P. infestans collected in WI Mefenoxam Sensitivity 0ppm 100ppm Avg colony diam on 100 ppm x 100% Avg colony diam on 0 ppm 2. Mating type A1? A2?

24 Genotypic characterization of P. infestans collected in WI Analysis of the Glucose-6-phosphate isomerase (Gpi) allozyme locus. Allozyme assay resolves clonal lineage and was performed directly from sporulating samples or spores from cultures.

25 What happens when both mating types are active on the same plant? US-8 is an A2 mating type & US-23 is an A1 mating type Hormone stimulation produces male and female fungal components which merge/sexually recombine to produce oospores oogonium antheridium

26 Number of oospores per sq mm of leaf tissue (US-22xUS-23) Tomato RB SP 951 (Katahdin with RB) Bittersweet nightshade Hairy nightshade Defender Satina Russet Burbank Jacqueline Lee Katahdin Brandywine Red 12C 16C 20C

27 Are oospores alive and capable of causing disease? Yes ~85% of oospores are viable or alive when removed from leaf tissues Of the living oospores, ~40% can germinate with potential to cause disease

28 Do oospores survive winter temperatures? US-8 and US-22 are A2 US-23 and US-24 are A1

29 Do oospores survive winter temperatures? US-8 and US-22 are A2 US-23 and US-24 are A1 Oospores could infect tomato leaves under controlled flooded soil conditions

30 Actual overwintering soil temperatures at HARS

31 Potato Disease Timeline April-May June July August September October Poor emergence, Rhizoctonia, Fusarium seed piece decay, Late blight Early blight, Blackleg, White mold, Botrytis, Brown spot Late blight, Potato early dying, Black dot, Pink rot Silver scurf, Pythium leak, Late blight, Scabs, Fusarium, Bac soft rot

32 Potato Late Blight Management Multifaceted and season-long cultural and chemical strategies Certified disease-free seed potatoes Cultivar selection for resistance is limited Destroy cull piles (20 May deadline in WI) Good seed handling, cutting, and curing practices with seed trt to limit seed piece-seed piece spread of late blight (mancozeb) Keep informed of late blight incidence in your region Foliar fungicide applied at ~50% emergence to limit seed to seedling late blight (if seed exposure was high) Use Blitecast or other disease forecasting tool to aid in timing of preventative fungicide applications Select effective fungicides and maintain a 7-day preventative program including base protectants and late blight-specific fungicides (5-day intervals in conducive weather on sus cultivars; 10-day intervals in dry/hot weather on tol cultivars) Scout routinely and critically in risk zones (around irrig towers, field edges, etc.) Control volunteers in area fields; control nightshade weeds Maintain foliar fungicide program beyond vine kill to harvest Consider post-harvest fungicides

33 Potato Cultivar Response to Late Blight Moderately Resistant Cultivar Name Serran Elba Kennebec Sebago Maturity Mid-Season Late Late Late Small, Fry, et al., 2014 Cornell

34 Potato Cultivar Response to Late Blight Moderately Susceptible Cultivar Name Dorita Rosa Castile Green Mountain Allegany Katahdin Russet Burbank Snowden Maturity Mid-Season Mid-Season Mid-Season Late Late Late Late Late Small, Fry, et al., 2014 Cornell

35 Potato Cultivar Response to Late Blight Cultivar Name Susceptible Caribe, Fabula, Ambra, Carrera, Adirondack Red, Andover, Norland, Dark Red Norland, Superior, Chippewa, Eramosa LaChipper, Carola, IdaRose, Kanona, LaRouge, Red Pontiac, Reddale, Redsen, Salem, Satina, Winema, Butte, French Fingerling, Hampton, Keystone Russet, Cherry Red, Goldrush, Norkota, Ranger Russet, Russet Gem, Shepody, Atlantic, Bake King, Eva, Keuka Gold, Manona, Monticella, NorDonna, Norwis, Pike, Reba, Red Lasoda #10, Russet Norkotah, Yukon Gold, Chieftain Austrian Crescent, LaRatte, Rideau, German Butterball, Amey, Banana, Marcy, All Blue, All Red, Genesee Maturity Early Mid-Season Late Small, Fry, et al., 2014 Cornell

36 What are the benefits of seed-applied fungicides? To limit surface-borne, seed-borne, and soilborne disease On potato, seed fungicide applications can control spread of disease from seed to seed during cutting, curing, pre-plant handling limit disease development from seed piece to seedling limit disease development from soil to seed and/or seedling

37 Seed-applied fungicides are one component of disease management program planting certified potato seed to aid in minimizing disease levels Proper handling and sanitation of storage, cutting, and curing facilities prior to planting can greatly impact disease, quality, and yield Good disease management in field

38 Application of seed treatments Usually applied right after cutting (esp. for late blight control) Formulation may be liquid or powder Be careful to avoid clumping or thick coating treatment as you can limit oxygen to seed piece and promote poor suberization and/or soft rot Good suberization is a critical component in disease management

39 Seed-Applied Fungicides for Potato in WI Fungicide, form, FRAC Active ingredient Diseases controlled Fungi-Phite, liq salts of phosphorous acid Late blight, Pink Rot, Pythium Oxidate, liq hydrogen dioxide Fusarium Curzate DF, liq slurry/mist, 27 cymoxanil (must be applied with another fungicide) Late blight Dynasty, liq slurry, 11 azoxystrobin Rhizoctonia, Silver Scurf, Black Dot Cruiser Maxx potato, liq, 12 fludioxonil, thiamethoxam Rhizoctonia, Fusarium, Silver Scurf CruiserMaxx Potato Extreme, liq, 12, 3 thiamethoxam, fludioxonil, difenoconazole Rhizoctonia, Fusarium, Silver Scurf, Black Scurf Maxim 4FS, liq, 12 fludioxonil Rhizoctonia, Fusarium, Silver Scurf Emesto Silver, liq, 7, 3 penflufen, prothioconazole Rhizoctonia, Fusarium, Silver Scurf, Black Scurf Penncozeb 80WP/75DF, liq, M3 mancozeb Late blight, Rhizoctonia Manzate Flowable/ Manzate Pro-Stick/Potato Seed Treater, liq, M3 mancozeb Late blight, Rhizoctonia Dithane F45/M45/DF, liq, M3 mancozeb Late blight, Rhizoctonia Mancozeb 6% Firbark, liq, M3 mancozeb Late blight, Rhizoctonia Polyram 80DF, liq, M3 metiram Late blight, Rhizoctonia Penncozeb 80WP/75DF, liq, M3 mancozeb Late blight, Rhizoctonia

40 Seed-Applied Fungicides for Potato in WI Fungicide, Form, FRAC Active ingredient Diseases Controlled Maxim MZ dust, 12, M3 fludioxonil, mancozeb Rhizoctonia, Fusarium, Silver Scurf Maxim PSP, dust, 12 fludioxonil Rhizoctonia, Fusarium, Silver Scurf Evolve Potato Seed Piece Trt, dust, 1, M3, 27 Moncoat MZ, dust, 7, M3 thiophanate methyl, mancozeb, cymoxanil flutolanil, mancozeb, contains alder bark Late blight, Fusarium, Rhizoctonia Late blight, Rhizoctonia, Fusarium, Silver Scurf

41 Relative performance of potato seed treatments on disease Seed Trt (fungicide component) Cruiser Maxx Potato (fludioxonil) Maxim 4FS (fludioxonil) Maxim MZ (fludioxonil+manco zeb) MonCoat MZ (flutolanil+mancoz eb) Moncut 70DF (flutolanil) Tops MZ (thiophanate methyl+mancozeb) Tops MZ Gaucho (thiophanate methyl+mancozeb) Rhizoc on Stems & Stolons Excellen t (E) Rhizoc on Daughter Tubers Fusarium Silver Scurf on Daughter Tubers Seed Borne Late Blight E E E P E E E E P E E E E G E E E E G E E E P P E Poor (P) E Good (G) G E P E G G Dr. Steve Johnson, Univ. of Maine Extension

42 Disease Forecasting for Late Blight Management Current research in multiple states to assess enhanced Blitecast tools, including Cornell s Late Blight Decision Support System tool (DSS) Tools are more comprehensive with locationspecific weather data (both models), and consideration for fungicide degradation, host resistance (DSS) Tools offer /text alerts allowing for real time updates and improved response times

43 Disease Forecasting for Late Blight Management Indicates timing of fungicides based on the favorability of the weather for disease development Assumes that pathogen is present Blitecast model (Hyre and Wallin) 1 st fungicide application at accumulation of 18 disease severity values (DSV) = relationship between air temperature and hours above RH target Subsequent applications based on accumulated DSVs (typically 5 to 7 day is pathogen present in region; 7-10 if pathogen not in region)

44 Considerations for foliar fungicide programs to manage late blight There is not one recommended fungicide program for all late blight susceptible potato fields in WI. Fungicide selections vary based on type of inoculum introduction, proximity to infected fields, crop stage, late blight strain, disease progress, and other diseases that may be in need of management.

45 Considerations for foliar fungicide programs to manage late blight QoI inhibitors Headline, Quadris, Reason (Group 11) can offer good late blight control at high rates under moderate pressure. Follow label for resistance management.

46 Under high late blight pressure Effective fungicides to include in programs are: Revus Top, Forum, Curzate 60DF, Ranman, Tanos, Gavel, Previcur Flex, or Omega. Mefenoxam containing fungicides such as Ridomil Gold MZ can also be highly effective in controlling late blight caused by strain US-23 (not US-8). Zampro is a newly registered late blight fungicide offering a novel mode of action fungicide in an effective pre-mix for late blight control. Maintain fungicide applications post vine kill to harvest (mancozeb) to limit tuber infection

47 Fungicides with broad spectrum activity Fungicide a.i. FRAC PHI potato Activity Bravo, Equus, Echo chlorothalonil M5 7 days protectant 16 lb a.i./acre limit/yr Dithane, Penncozeb, Mancozeb Kocide, Champ mancozeb M3 3 days protectant 11.2 lb a.i./acre limit/yr;excellent tuber LB control; aids yield copper (not all coppers OMRI approved) M1 0 days protectant Agri-tin, Supertin triphenyltin hydroxide (TPTH) 30 7 days protectant best in late sprays (final 2-3)/restricted use fung Polyram 80DF metiram M3 3 days protectant EBDC like mancozeb and counts in total a.i./yr/acre

48 Reduced risk fungicides with specific late blight activity Fungicide a.i. FRAC PHI potato Acrobat/ Forum Activity dimethomorph 40 4 days Systemic adjuvant enhances management/can be applied post vine kill; antisporulant; rainfast Curzate cymoxanil days Locally Systemic rainfast 2 hrs/mix with protectant;curative Fosphite, Phostrol, Crop-Phite, Prophyt, Rampart phosphorous acid formulations Gavel mancozeb + zoxamide NC 0 days Systemic phytotox possible applied at low carrier volumes;tuber late blight control at multiple apps + hi rates; post-harvest applic; not great antisporulant M days Protectant do not apply >6 apps/crop/yr; reduce tuber blight;rainfast Omega fluazinam days Protectant excellent tuber blight control; rainfast Previcur Flex propamocarb hydrochloride days Systemic and Contact antisporulant;rainfast;curative; good protectant on leaf, new growth, stem

49 Reduced risk fungicides with specific late blight activity Fungicide a.i. FRAC PHI potato Activity Ranman cyazofamid 21 7 days Protectant, Limited Systemic Good on leaf and tuber blight;rainfast Revus Top difenoconazole + mandipropamid Ridomil Gold MZ, Ridomil Gold Copper days Preventative, Systemic, Curative rainfast;excellent protectant on leaf blight mefenoxam + mancozeb 4 + M3 14 days Systemic works on US-23 not US-8 Tanos cymoxanil + famoxadone days Locally Systemic, Curative tank mix with protectant; excellent curative;good leaf protectant;rainfast Zampro ametoctradin + dimethomorph days Systemic and Protectant New registration includes two a.i.s with excellent activity on late blight, Forum plus new a.i.

50 Post-harvest Late blight control begins with good basic storage management Manage bruise from vine kill through the harvest process Cure tubers (heal wounds, cuts, incomplete skin set), F for 2-3 weeks Avoid storing frosted tubers (cellular breakdown, bacterial invasion) Assess tubers at piling to determine disease incidence and severity for tailoring treatment/environmental management

51 Common oomycete diseases of stored potatoes Pink rot (Phytophthora erythroseptica) favored by wet soil conditions, infection apparent at harvest or latent and can develop and spread in storage, no foliar symptoms Late blight (Phytophthora infestans) favored by wet soil conditions, infection apparent at harvest or latent and can develop and spread in storage, has foliar symptoms Pythium leak (Pythium ultimum & other species) favored by wet soil conditions, injury or open lenticels required for infection, typically occurs at time of harvest or after, can develop in storage, no foliar symptoms

52 New fungicide for postharvest potato disease control Syngenta s Stadium Received Section 2 registration Nov Labeled for use in controlling Fusarium dry rot and Silver scurf in storage Our research also indicates outstanding control of Pink rot and Late blight not on label at this time One application can be made post-harvest Cannot be applied to seed potato or cut seed Not for ventilation application at this time Contains 3 active ingredients Azoxystrobin (Quadris) Fludioxonil (Maxim) Difenoconazole (Inspire, Top)

53 Post-harvest Fungicide Treatments for Winter 2012 Late Blight Trial Trt # Treatment, Manufacturer Active ingredient Rate/ton tubers* 1 Untreated, Non-inoculated Not applicable (NA) NA 2 Untreated, Inoculated NA NA 3 Ozone, Ron s Refrigeration ozone 10 ppm 4 Phostrol, Nufarms salts of phosphorous acid 6.4 fl oz 5 Ozone, BioSafe Systems + Phostrol, Nufarms ozone + salts of phosphorous acid 10 ppm fl oz 6 Stadium, Syngenta fludioxonil, azoxystrobin, difenoconazole 1.0 fl oz 7 Stadium Component (A9859), Syngenta fludioxonil 0.6 fl oz 8 Stadium Component (A12705), Syngenta azoxystrobin 0.6 fl oz 9 Stadium Component (A8574), Syngenta difenoconazole 0.3 fl oz *Except where specific Conducted at the Univ. of WI Hancock Ag Res Station Storage Res Facility

54 Disease Incidence Late Blight Storage Trial DPI 100% e 90% 80% 70% 60% 50% 40% 30% 20% 10% 0% d c b a a a a a Treatment # TRT # Treatment Active ingredient 1 Untr/Non-inoc 2 Untr/Inoc 3 Ozone ozone 4 Phostrol phosphorous acid 5 Ozone+Phostrol ozone+phos acid 6 Stadium fludi+azoxy+difen 7 Stad Comp A fludioxonil 8 Stad Comp B azoxystrobin 9 Stad Comp C difenoconazole

55 Post-harvest Late Blight Control Ozone reduced late blight incidence compared to the control, but was not as effective as other treatments limited external mycelia and other secondary decay species may be effective in limiting a disease hot spot in bin Oxidate significantly reduced incidence in 2011, not in 2010 Phostrol significantly reduced incidence and severity of infection Stadium significantly reduced incidence for trials azoxystrobin component responsible for late blight control not currently labeled for late blight control

56 Managing Potato Late Blight through state regulation

57 Managing Potato Late Blight through state regulation

58 Late Blight Summary Points Late blight has been occurring more often in recent years. Expected to continue. New pathogen genotypes affect disease occurrence. Genotype info important for efficacy of mefenoxam/metalaxyl. Both mating types of the pathogen are in US; sexual reproduction is a concern. USABlight website and university extension resources provide current info on occurrence and control Disease forecasting aids in preventative management Use of fungicides is effective in limiting late blight at multiple stages of production cycle

59 Thank you! Information Resources UW Vegetable Extension Team Website University of Wisconsin Vegetable Disease Website (newsletter access)