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Disease forecast 2011 : Viruses and stripe rust

Disease forecast 2011 : Viruses and stripe rust. Dr. Mary Burrows Montana State University Bozeman, MT. Virus diseases in MT. Occur sporadically Difficult to predict. Host. Vector. Pathogen. Environment. Wheat streak mosaic virus. Infects both winter and spring wheat

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Disease forecast 2011 : Viruses and stripe rust

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  1. Disease forecast 2011: Viruses and stripe rust Dr. Mary Burrows Montana State University Bozeman, MT

  2. Virus diseases in MT • Occur sporadically • Difficult to predict Host Vector Pathogen Environment

  3. Wheat streak mosaic virus • Infects both winter and spring wheat • Earlier infection = greater yield loss • Grassy weeds, volunteer wheat, corn, etc. can harbor both WSMV and the mite vector

  4. Disease cycle of WSMV

  5. 2010: Distribution of WSMV

  6. Weed Host: Volunteer Wheat

  7. Average yield loss (%) due to mechanically inoculated WSMV in winter wheat, 2008-2010, Bozeman *Hail damage

  8. Average yield loss (%) due to mechanically inoculated WSMV in spring wheat, 2008-2010, Bozeman

  9. Insecticides/Acaracides: NONE!

  10. C. Tharp, Southern Ag Research Center, Huntley, MT, 2010

  11. Barley yellow dwarf virus: The Host • Infects barley, wheat, oats, rye, corn, triticale, rice • Resistance has been developed, but predicting the virus and aphid populations from year to year can be difficult (no resistance in Montana varieties)

  12. Barley yellow dwarf virus(BYDV) • Family Luteoviridae • Genera Luteovirus, Polerovirus, Enamovirus • First classified by primary aphid vector • MAV:Macrosiphum (Sitobion) avenae • PAV:Rhopalosiphumpadiand S. avenae • RMV:Rhopalosiphummaidis • SGV: Schizaphisgraminum • RPV: Rhopalosiphumpadi (& S. graminum) • (Cereal yellow dwarf virus – RPV)

  13. Russian wheat aphid RWA is NOT a vector of BYD Note leaf damage caused by feeding toxins (RWA and greenbug) Corn leaf aphid English grain aphid Greenbug

  14. 2010: Distribution of BYDmajority of samples tested negative, even in the counties with confirmed BYD

  15. Control of WSMV vs. BYDV • Insecticides are effective against BYD, but generally not economical; no acaracides are available for WCM/WSMV control • Plant resistance can be effective, but viruses and mites evolve rapidly; none available in MT • Preventmovement from volunteer plants by getting rid of volunteers before planting (green bridge)

  16. The rusts Stripe Stem Leaf Jim Berg, MSU

  17. Stripe rust: gen’l WA or Canada Leaf rust, stem rust: ‘Puccinia pathway’

  18. What qualifies as excitement for a plant pathologist:

  19. Aecia on barberry Uredinia on Kentucky bluegrass Pycnidia on barberry Aecia on barberry Uredinia on wheat Jin, Szabo and Carson, Plant Dis., 2010

  20. Fall 2010: Distribution of stripe rustDoes occur on spring wheat, but generally too late to be significant

  21. Fall infection by stripe rust, 2010 WSMV and stripe rust: lucky guy!

  22. Yellowstone Promontory Johnston & Grey, 2006 Stripe Rust: variety resistance is very effective at reducing yield losses Susceptible variety Resistant variety

  23. Influence of fungicide application on two stripe-rust infected WW varieties Yellowstone (Resistant) c c c c Big Sky (Susceptible) b b b a (Quilt, 14oz, Bozeman 2007; P < 0.001, LSD = 6.3)

  24. Influence of fungicide application on susceptible SW variety, McNeal Quilt, Bozeman 2007, P = 0.50

  25. Stripe rust variety evaluation: Winter wheat Bozeman, 2006 Note: Jagalene is susceptible to the new strain, had high disease severity at Huntley, 2010 Grey, 2006

  26. Xiangming Chen, WSU, 2010Stripe rust would have caused 54% yield loss in WA without fungicide application in 2010 if all varieties were as susceptible as PS279If all resistant cultivars were grown, 1% yield loss with no fungicide application Resistant check Susceptible check

  27. Acknowledgements Dai Ito, Zach Miller, Matt Moffet, Linnea Skoglund GPDN: Jim Stack & all state reps and diagnosticians MSU County Extension Agents

  28. Ug99 First reported in Uganda in 1999 --Pretorius et al. 2000 Plant Dis 84:203 Virulent on Sr31 Sr31 is located on 1BL.1RS translocation Also carries Lr26, Yr9 Increased adaptation and higher yield. As a result, widely spread in wheat worldwide Helped to reduce stem rust population worldwide Virulence to Yr9, originated in the eastern Africa in mid 80s, caused worldwide epidemics

  29. TTKS In 2002 and 2004, CIMMYT nursery planted in Njoro, Kenya were severely infected by stem rust. In 2005, we identified Kenyan isolates from 2004 were race TTKS. • --Wanyera, Kinyua, Jin, Singh 2006 Plant Dis 90:113

  30. Broad virulence of TTKS to North American spring wheat • US spring wheat CVs of the Northern Great Plains, known to have broad-based resistance to stem rust, were mostly susceptible (84%). • 500 CIMMYT CVs released since 1950’s, 84% were susceptible. Conclusion: Ug99 possesses a unique virulence combination that renders many resistance genes ineffective. Jin & Singh, 2006, Plant Dis:90:476-480

  31. Ramification of Sr24/Sr36 virulence to US Wheat based on testing of 2007 elite breeding germplasm % of resistance to Type Entry TTKSK TTKST TTTSK (Ug99) Sr24v Sr36v Hard red spring 89 21% 12% 21% Hard red winter 416 29% 15% 28% Soft red winter 377 27% 25% 11% Western wheat 60 3% 3% 3% Total 942 26% 18% 19%

  32. Current status of Ug99 • New races constantly evolving • Ug99 stalled in Iran due to long drought • If moves to Pakistan/India will affect 15% of world’s wheat crop that feeds 1 billion of the world’s poorest people • Strain of stem rust in India that overcomes Sr25 • ‘Likely’ Ug99 has already spread beyond Iran - Rick Ward, co-coordinator of the Durable Rust Resistance in Wheat project, based at Cornell university; http://rustopedia.org/traction/permalink/Resources905

  33. Projected potential pathways for Ug99 based on the migration of Yr9 virulence Singh et al. 2006. CAB Review 1, 54

  34. Ug99 migration 2007 2006 2006 2003? 2005 Singh et al. 2008. Advances in Agronomy v98 2001? 2004 1998

  35. The good news • Phil and Luther are both working on it already! • Li Huang, PSPP, has identified spring wheat mutants from a population derived by Mike Giroux with resistance to leaf, stem, and stripe rust – including all Ug99 derivatives • Fungicide trials with great results • Communication and education ramping up!

  36. Triazole + Strobilurin Triazoles

  37. Fungicide modes of action: Triazoles • FRAC group 3 • DMI (demethylation) inhibitors; biosynthesis of sterols in fungal cell membrane; spore penetration and mycelial growth • Provides 14-21 days of protection • Medium risk of resistance development • Greater mobility in plant than strobilurin fungicides • Most widely used class of fungicide in the world • Control a wide array of fungal diseases • Protective and curative effects (if applied early in disease development)

  38. Fungicide movement in the plant From: Tenuta, A., D. Hershman, M. Draper and A. Dorrence. 2007. Using foliar fungicides to manage soybean rust.. Land-Grant Universities Cooperating NCERA-208 and OMAF. Available online at http://www.oardc.ohio-state.edu/SoyRust/

  39. Fungicide modes of action: Strobilurins • FRAC group 11 • QoI (quinone outside) inhibitors (respiration); spore germination, penetration, and mycelial growth • Provides 14-21 days of protection • High risk of resistance development because it has a very specific mode of action (they block electron transfer at the site of quinol oxidation (the Qo site) in the cytochrome bc1 complex, thus preventing ATP formation) • Originally isolated from wood-rotting fungi Strobilurus tenacellus • ‘Reduced-risk’ pesticide (pose less risk to human health than other chemical options at the time of registration by EPA) • Control a wide array of fungal diseases • Excellent preventative fungicides, but limited curative effects • “Plant health benefit” independent of disease control?

  40. Figure 1. Mobility of trifloxystrobin, an example of a QoI fungicide. http://www.apsnet.org/education/AdvancedPlantPath/Topics/Strobilurin/top.htm

  41. Stem rust fungicide trial • RateActive IngredientCompany • Control • Proline 480 SC 5.3 oz Prothioconazole Bayer • 3. Prosaro 421 SC 7.5 oz Tebuconazole + Prothioconazole Bayer • 4. Quilt 14 oz Azoxystrobin + PropiconazoleSyngenta • 5. A15590C 14 oz Azoxystrobin + PropiconazoleSyngenta • 6. Alto 100SL 4 oz CyproconazoleSyngenta • 7. Caramba 13.5 oz Metconazole BASF • 8. Twinline 9 oz Pyraclostrobin +Metconazole BASF • 9. Headline 2.09EC 7.5 oz Pyraclostrobin BASF • 10. Gem 500 SC 2.4 oz Trifloxystrobin Bayer

  42. Yield, stem rust fungicide trial2009, Bozeman d bcdcd cd bcbc bc b a a

  43. Control (no fungicide), 14 daa

  44. Strobilurin fungicides, 14 daa Headline Gem 500 SC

  45. Strobiliurin + Trizole, 14 daa Quilt Quilt Xcel

  46. Strobiliurin + Trizole, 14 daa Prosaro Twinline

  47. Trizole fungicides, 14 daa Alto Caramba Proline

  48. Compare sprayed and unsprayed plots

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