1. The stripe rust epidemic of 2011: why? and what next? Dr. Mary Burrows Montana State University Bozeman, MT

2. Why was stripe rust so bad this year? 1.Widespread fall infection 2.Extended fall 3.Deep, lengthy snow cover 4.Favorable spring temperatures 5.Flooding created wet, humid conditions throughout the year 6.Even after day temps became hot, night temps were favorable for infection (50-70F) 7.A widely planted, susceptible variety (Genou) 8.New strains 9.April: alerts from Xianming Chen that stripe rust was off to an ‘early start’ in WA

3. Fall infection by stripe rust, 2010

4. Fall 2010: Distribution of stripe rust

5. Reports of stripe rust in Montana 20 June, 2011 (Diagnostic lab samples)

6. Stripe rust spore cloud: 23 June, 2011 near Kremlin (Hill Co.) Photo courtesy of Ryan McCormick

7. Degree day map, 9 May, 2011 First reports from Ronan, Kalispell

8. Degree day map, 24 May, 2011 Reports from Havre, Fort Benton, Great Falls Mary: “Genou is what??? Send a sample”

9. June 1: “Dan/Jeannie (Pondera, Toole Co) – it’s coming your way”

10. June 10: Pondera Co’s 1 st sample came into the office

11. Why didn’t the epidemic stop when it got hot? Stripe rust disease progress is tied to night time temperatures Great Falls 1 May to 30 July 50 to 70°F

12. The rusts of wheat Jim Berg, MSU Stripe Stem Leaf Yellow Black Red

13. Rust diseases are not mutually exclusive

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

15. Normally, this is wheat

16. Great Falls area, 23 June, 2011 WW Variety: Genou

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

20. CDC FalconYellowstone

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

22. Seedling infection vs. adults Seedling infections are often not in ‘stripes’ –Yellow rust Seedling infections tend to be strain – specific (single genes) – easily overcome by the pathogen Adult resistance is non-race specific, more durable Seedling and adult plant responses can be different HTAP resistance: High Temperature, Adult Plant resistance – doesn’t kick in until after stem elongation (Feekes 4-9; Zadocks 30-39) and average night temperatures remain above 50 and day temps are between 77 and 86 F

23. Current classifications: Winter Wheat http://plantsciences.montana.edu/Crops/2011data/2011WinterWheatVarieties.pdf Tables 3, 4, and 14 http://plantsciences.montana.edu/Crops/2011data/2011WinterWheatVarieties.pdf TolerantModerateSusceptible JagaleneAboveBigSky JerryHatcherCDC Buteo JudeeNuWestCDC Falcon LedgerRampartGenou NuFrontierRockyMorgan YellowstoneVanguardNeeley WahooNuWest NuSky Pryor

24. Current classifications: Spring wheat http://plantsciences.montana.edu/Crops/2011data/2011WinterWheatVarieties.pdf Pages 23 and 24 http://plantsciences.montana.edu/Crops/2011data/2011WinterWheatVarieties.pdf TolerantModerateSusceptible BrennanConanAP604CL BynumCorbinHank ChoteauHyalite FreyrJedd JennaKnudsen KelbyMcNeal ReederMott VidaNorris VoltONeal Note: this needs to be updated with 2011 data

25. Xiangming Chen, WSU, 2010 Stripe rust would have caused 54% yield loss in WA without fungicide application in 2010 if all varieties were as susceptible as PS279 If all resistant cultivars were grown, 1% yield loss with no fungicide application Resistant check Susceptible check

26. Fungicides Ron Muzzana, 2011

27. StrobilurinsTriazoles Mode of actionFRAC group 11: QoI (quinone outside) inhibitors (respiration); spore germination, penetration, and mycelial growth FRAC group 3 : DMI (demethylation) inhibitors; biosynthesis of sterols in fungal cell membrane; spore penetration and mycelial growth Residual14-21 days of protection Resistance development High (specific MOA)Medium Mobility in plantTranslaminar and systemic High ProtectionProtective only (kill germinating spores) Protective and curative Note: these are generalizations about fungicide classes

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

29. On-farm/on-station fungicide trials: flag applications (sprayed 9-10 June, rated 7-8 July) Disease severity (plot rating, avg % leaf area covered by active stripe rust pustules) TreatmentRateActive ingredient(s)Company Hill Co. (var. Genou ) Toole Co. (var. Genou ) Liberty Co. (var. Genou) Control 11.254.6252.5 Headline3 oz/APyraclostrobinBASF 3.750.3750 Headline6 oz/APyraclostrobinBASF 0.12500 Quilt7 oz/A Azoxystrobin + Propiconazole Syngenta 1.2500 Quilt14 oz/A Azoxystrobin + Propiconazole Syngenta 000 Stratego4 oz/A Trifloxystrobin + Propiconazole Bayer 1.3750.1250 Stratego8 oz/A Trifloxystrobin + Propiconazole Bayer 000 Quadris4 oz/AAzoxystrobinSyngenta 1.2500 Tilt2 oz/APropiconazoleSyngenta 000 Sprayed too early for max SR

30. Stripe rust on WW Bozeman, 2011 – Bynum (Resistant to stripe rust) Treatment Yield (bu/A) Disease (% flag leaf area 29 June) Untreated control25.88.2a Headline SC3 oz/A29.84.2b Headline SC6 oz/A29.52.9bcd Quilt Xcel14 oz/A34.21.6ef Quilt Xcel7 oz/A32.42.3def Stratego8 oz/A37.62.0def Stratego4 oz/A31.33.4bc Tilt4 oz/A28.72.4cdef Tilt2 oz/A23.81.8ef Quadris flowable12 oz/A31.61.5f Quadris flowable6 oz/A25.52.7bcde P-value >0.10<0.001 Sprayed 5 June, Feekes 5, 2011

31. Bynum Winter Wheat: Resistant No yield benefit to tillering or flag fungicide application (Priaxor, Headline, Evito, Quilt Xcel, Twinline study, Bozeman, 2011) Photo: M. Moffet

32. Stripe rust on SW Bozeman, 2011 – Vida – MR to stripe rust ProductRateTiming Disease 12 Aug (% flag) Incidence 12 Aug (%) Yield (bu/A) Control237081bc Stratego YLD + Wolverine 1.5 oz/A + 1.7 pt/A Tillering329584abc Stratego YLD3 oz/ATillering178380c Stratego YLD1 oz/AFlag24086ab Absolute 500 SC 3 oz/AFlag0087a Prosaro 421 SC 3 oz/AFlag0681bc Prosaro 421 SC 4 oz/AFlag0586ab Prosaro 421 SC 10.5 oz/AFlowering0585abc P = 0.11

33. Glume infection of stripe rust

34. ‘Rescue’ spraying? Remember your PHI! Hunger and Jackson. Foliar fungicides and wheat production in Oklahoma. http://lubbock.tamu.edu/wheat/pdfs/osufoliarfunghandout04.pdf

35. Economic impact? Montana growers spent ~$15 mil. on fungicide Fungicides saved growers ~$30 mil. Yield losses cost growers ~$48 mil. Not spraying resistant varieties saved ~$12 million Source: estimates from a grower survey, October 2011 (Burrows)

36. What does ‘strain’ mean when talking about stripe rust? Stripe rust is characterized by the pathogenic reaction on a series of wheat lines called ‘differentials’ Virulence patterns have changed Stem rust differentials

37. New strains are more aggressive Moon and Milus, 2011 “Even though there was more initial inoculum of isolate AR90-01 [‘old,’ PST- 3], isolate AR03-33 [‘new,’ PST-78] caused significantly more disease around the transplants in the spring at both Fayetteville and Kibler”

38. New strains infect plants at higher temperatures Milus, E. A., Seyran, E., and McNew, R. 2006. Aggressiveness of Puccinia striiformis f. sp. tritici isolates in the south-central United States. Plant Dis. 90:847-852. At 54°F, old and new isolates had similar latent periods and spore germination percentages. However, at 64ºF, new isolates averaged 2 days less for latent period and double the spore germination compared with old isolates. Therefore, the new isolates are better adapted and, thus, more aggressive at warmer temperatures than the old isolates.

39. A number of new strains were characterized after a severe epidemic in 2000 Chen, X. M., Moore, M., Milus, E. A., Long, D. L., Line, R. F., Marshall, D., and Jackson, L. 2002. Wheat stripe rust epidemics and races of Puccinia striiformis f. sp. tritici in the United States in 2000. Plant Dis. 86:39-46.

40. Chen, X. M., Moore, M., Milus, E. A., Long, D. L., Line, R. F., Marshall, D., and Jackson, L. 2002. Wheat stripe rust epidemics and races of Puccinia striiformis f. sp. tritici in the United States in 2000. Plant Dis. 86:39-46.

41. How do new strains originate? Aecia on barberry Uredinia on Kentucky bluegrass Pycnidia on barberry Aecia on barberryUredinia on wheat Jin, Szabo and Carson, Plant Dis., 2010

42. What qualifies as excitement for a plant pathologist:

43. 2010 Stripe rust strains (PSTv-#) 16,14 14 38 14, 44 22,39 46

44. 2011 Stripe rust strains (PSTv-#) Data updated 9 Dec, 2011 11 11,14 14 14,37 37 17

45. So what do those numbers mean? Virulence on differential lines of wheat Virulence on differential lines YearStrain1-1011-2021-50Other 2010PSTv-14 1, 2, 6, 7, 8, 91727, 43, 44Tr1, Exp2, Tye PSTv-16 1, 2, 6, 7, 8, 91726, 27, 43, 44Exp2, Tye PSTv-22 2 PSTv-38 2, 6, 7, 8, 926, 27, 44Tr1, Exp2 PSTv-39 2, 6, 7, 8, 926Tr1, Exp2 PSTv-45 2, 6, 7, 8, 926, 27, 43, 44Tr1, Exp2 PSTv-46 2, 6, 7, 8, 91726, 27, 43, 44Tr1, Exp2 2011PSTv-11 1, 2, 6, 7, 8, 91727, 43, 44Exp2, Tye PSTv-14 1, 2, 6, 7, 8, 91727, 43, 44Tr1, Exp2, Tye PSTv-17 1, 2, 6, 7, 8, 91727, 43, 44Sp, Exp2, Tye PSTv-37 2, 6, 7, 8, 91727, 43, 44Tr1, Exp2

46. What’s next? PSTv-4 and PSTv-17 are virulent against differential line Sp (“Spalding Prolific, Yr-SP) YrSP virulence is in low frequency worldwide Last year Yr-SP virulent races were detected in low frequency and in 2011 increased significantly PSTv-4 is currently in Washington, Oregon, Utah and Idaho (not MT); PSTv-17 is in MT Bottom line: races are changing very fast; variety reactions will change, also: Scout crops, recognize the reaction types and manage appropriately

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

48. So, what about next year? Dry fall! Hot spots due to prevented planting; WW seeded very early Plant a resistant variety Use a seed treatment Fall fungicide is generally not economical Plan on a full rate of fungicide when spraying weeds at tillering (blends preferred) on susceptible varieties if the weather is favorable for disease development Although stripe rust got all the glory, a lot of yield losses were due to root and crown rots Community disease

49. Diagnostic lab: routine functions and agricultural biosecurity Process approximately 2000 samples/yr (~80% homeowner/horticulture) Free to you 100% grant funded staff, supplies, travel –Space and utilities provided by MSU Sample submission is important Good sample = good answer

50. Network Responsibilities Data collection (detectors/diagnosticians) Communications system Information storage and management Data analysis New events and analysis of new appearance Pattern recognition Unusual patterns of endemic problems GIS Event propagation Tracking Reporting and alerts Link to State Departments of Ag and US regulatory agencies

51. Acknowledgements Dai Ito, Matt Moffet, Zach Miller, Linnea Skoglund MSU County Extension Agents USPEST.ORG

52. Which seed treatment to use? Very little data, and results showing yield benefit may not be solely due to stripe rust control Whether any products will prevent overwintering is unknown Within-field overwinter inoculum may be lower, but this is still an airborne disease Plant disease management reports: www.planthealthmanagement.org – search for Xianming Chen and stripe rust (PDMR 1: ST005; 1: ST006; 1: ST007) www.planthealthmanagement.org

54. Yield, stem rust fungicide trial 2009, Bozeman a bcd cd bc a cd d bc b

55. Yield, stem rust fungicide trial 2011, Bozeman

56. Compare sprayed and unsprayed plots

57. Control (no fungicide), 14 daa

58. Strobilurin fungicides, 14 daa Headline Gem 500 SC

59. Strobiliurin + Trizole, 14 daa Quilt Quilt Xcel

60. Strobiliurin + Trizole, 14 daa Prosaro Twinline

61. Trizole fungicides, 14 daa Alto Proline Caramba