Stripe Rust• Caused by Puccinia striiformis • Host is primarily wheat

– Barley and some perennial grasses may be infected

Stripe rust vs. other foliar diseases

Tan spotCephalosporium stripe

Stem rust

Stripe RustStripe rust

Leaf rust

Stem rust

Yellowstone

Promontory

Johnston & Grey, 2006

Resistant

Susceptible

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Influence of fungicide application on two stripe-rust infected WW varieties

(Quilt, 14oz, Bozeman 2007; P < 0.001, LSD = 6.3)

Yellowstone (Resistant)

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Influence of fungicide application on susceptible SW variety, McNeal

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Fungicide application

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Quilt, Bozeman 2007, P = 0.50

Stripe rust history in the United States and Montana

• Discovered in 1915 by a Danish scientist visiting AZ• Found in herbarium specimens from WA in 1892• Probably on native grasses since humans crossed

into North America• Epidemics diminished 1930s until 1950s

– Increased wheat production– New cultivar, Lerma Rojo, in Mexico that was highly

susceptible

Line. 2002. Annu. Rev. Phytopathol. 40:75-118

History, cont’d• 1960-1967 severe epidemics

– Variety Omar very susceptible, widely planted– Sharp and Hehn (1963); stripe rust is probably

endemic in Gallatin Valley and Flathead Lake area

• Army and USDA funded research as potential biological weapon in the Cold War; impact on national security

• Nugaines released in 1965, major cultivar planted until 1981, durable resistance for 40 years

• 1968-2000s, not a major pathogen, focus shifted to breeding resistance to stem and leaf rusts– Also, weather not as conducive for epidemics

Line. 2002. Annu. Rev. Phytopathol. 40:75-118

Stripe rust history

• First described in 1777 in Europe• Became a problem in MT early 1900s• 2003: WA 25% yield loss

– Favorable weather and new races

• Survived winter in MT• New strains can grow when

temperatures are warmer

Stripe rust pathogen• Can travel on wind from other wheat-

producing regions• Survives on both winter and spring wheat

(living tissue)– GREEN BRIDGE

• Not as common in the western region because there is less winter wheat

• Favored by cool, wet conditions• Barley is susceptible, but it may escape

infection due to early maturity

X

Stripe rust pathogenNew isolates grow faster at higher temperatures

+New isolates have significantly lower latent

periods at 18C than 12 C (64F/54F)

= Stripe rust caused by new isolates tends to develop faster at relatively high temperatures

Stripe rust pathogenPST-102

Yellowstone

Promontory

Johnston & Grey, 2006

Stripe rust pathogen

• Survives on both winter and spring wheat (living tissue)– GREEN BRIDGE

• Favored by cool, wet conditions

• Barley is susceptible, but it may escape infection due to early maturity

X

Stripe rust control• Eliminate green bridge• Use resistant varieties

– plantsciences.montana.edu/crops• If you don’t plant a resistant variety, you may

need to apply fungicide – need 4-5 bu yield gain to pay for the application cost

• If stripe rust is present: Spray between the period of stem elongation and heading – need to protect the flag leaf. Check the preharvest interval on the fungicide label

Stripe rust variety evaluation: Winter wheat

Kalispell and Bozeman 2006• Resistant: Bighorn, Jagalene, NuFrontier,

NuHorizon, Quantum, Promontory, Rampart, Yellowstone

• Moderately resistant: Jerry, Ledger, Pryor

• Susceptible: CDC Falcon, Genou, Rocky

• Very susceptible: Above, BigSky, Morgan, Neeley, NuSky, NuWest, Paul

Stripe rust variety evaluation: Winter wheat

Bozeman, 2006Variety Yield (Bu/a)

% Stripe rust (June 28)

Yellowstone 99 7Promontory 93 9

Jerry 89 10NuFrontier 85 10Rampart 80 18

Pryor 80 42Jagalene 79 12

CDC Falcon 78 55Genou 71 36Ledger 70 41Neeley 70 72NuSky 66 82

NuWest 65 83Correlation = -0.749 p < 0.001

Grey, 2006

Stripe Rust Corr. w/ Yield Corr. w/ Test Wt. Avg. % R value P-value R value P-value

Bozeman Intrastate 19.1 -0.721 <.0001 -0.530 <.0001

Bozeman Intrastate 36.4 -0.749 <.0001 -0.493 0.0003

Kalispell Intrastate 31.9 -0.617 <.0001 -0.372 0.0086

Bozeman Soft White 29.9 -0.562 0.0235 0.396ns 0.1284

Kalispell Soft White 7.6 -0.786 0.0003 0.519 0.0392

Bozeman Advanced 19.2 -0.768 <.0001 -0.664 <.0001

Bozeman Sawfly 10.3 -0.615 <.0001 -0.572 <.0001

Bozeman Preliminary A 65.1 -0.849 <.0001 -0.567 <.0001

Bozeman Preliminary B 31.4 -0.872 <.0001 -0.233ns 0.1086

Bozeman S. Reg. Perf. 31.0 -0.081ns 0.5746 -0.100ns 0.4899

Bozeman N. Reg. Perf. 62.5 -0.205ns 0.2770 -0.009ns 0.9604

Bozeman W. Reg. Hard 37.1 -0.376ns 0.0703 0.272ns 0.1990

Bozeman W. Reg. Soft 13.6 -0.409 0.0164 -0.069ns 0.7002

Bzn. Statewide Triticale 37.1 -0.544 0.0295 0.353ns 0.1798

Bzn. PPO/Protein Test 68.8 -0.725 <.0001 -0.379 <.0001Grey, 2006

Stripe Rust Corr. w/ Yield Corr. w/ Test Wt. Avg. % R value P-value R value P-value

Bozeman Intrastate 19.1 -0.721 <.0001 -0.530 <.0001

Bozeman Intrastate 36.4 -0.749 <.0001 -0.493 0.0003

Kalispell Intrastate 31.9 -0.617 <.0001 -0.372 0.0086

Bozeman Soft White 29.9 -0.562 0.0235 0.396ns 0.1284

Kalispell Soft White 7.6 -0.786 0.0003 0.519 0.0392

Bozeman Advanced 19.2 -0.768 <.0001 -0.664 <.0001

Bozeman Sawfly 10.3 -0.615 <.0001 -0.572 <.0001

Bozeman Preliminary A 65.1 -0.849 <.0001 -0.567 <.0001

Bozeman Preliminary B 31.4 -0.872 <.0001 -0.233ns 0.1086

Bozeman S. Reg. Perf. 31.0 -0.081ns 0.5746 -0.100ns 0.4899

Bozeman N. Reg. Perf. 62.5 -0.205ns 0.2770 -0.009ns 0.9604

Bozeman W. Reg. Hard 37.1 -0.376ns 0.0703 0.272ns 0.1990

Bozeman W. Reg. Soft 13.6 -0.409 0.0164 -0.069ns 0.7002

Bzn. Statewide Triticale 37.1 -0.544 0.0295 0.353ns 0.1798

Bzn. PPO/Protein Test 68.8 -0.725 <.0001 -0.379 <.0001Grey, 2006

Stripe rust variety evaluation: Spring wheatHuntley, 2005

• Resistant: Conan, Freyr, Buck Pronto, Alsen, Choteau

• Moderately resistant: Agawam, Reeder, Fortuna, Scholar, Explorer

• Susceptible: Knudson, Outlook, Hank, Ernest

• Very susceptible: NorPro, McNeal

Fungicides for stripe rust

Quilt, 14 fl oz/a

• Contact fungicides such as Bravo are not effective

• Tilt is marginally effective• Tilt, Quadris, Stratego, Headline and Quilt are

registered for stripe rust control on wheat and barley

Fungicides increase yield and test weight in stripe rust susceptible varieties under stripe

rust pressure (Bozeman, 2006)Yield (bu/a) Test weight

Resistance reaction

No fungicide

Quadris (14 oz/a) % loss

No fungicide

Quadris (14 oz/a)

Nuwest

parent VS 58.9 71.1 17 56.8 59.3

BigSky

parent VS 72.6 88.9 18 60.0 60.4

NuWest VS 68.5 107.4 34 57.7 60.6

Rampart

parent R 85.1 90.1 6 60.3 60.4

McNeal S 72.9 80.4 9 55.6 55.6

Fungicides increase yield and test weight in stripe rust susceptible varieties under stripe

rust pressure (Bozeman, 2006)Yield (bu/a) Test weight

Resistance reaction

No fungicide

Quadris (14 oz/a) % loss

No fungicide

Quadris (14 oz/a)

Nuwest

parent VS 59 71 17 57 59

NuWest VS 69 107 34 58 61

BigSky parent S 73 89 18 58 61

Rampart

parent R 85 90 6 60 60

McNeal S 73 80 9 56 56Grey, 2006

Even ¼ rate fungicide at flag leaf stage can improve yield under stripe rust

pressure (Bozeman 2006)Fungicide rate Yield (bu/a)(100% = 14 oz/a Quilt) Rep 1 Rep 2

No fungicide 65.9 66.1

¼ rate 82.8 74.5

½ rate 88.9 77.7

¾ rate 84.2 74.4

full rate 88.4 69.6

Influence of fungicide application on 2 stripe-rust infected WW varieties

Quilt, 14oz, Bozeman 15 June, 2007; P < 0.004, LSD = 28Stripe rust first confirmed Bozeman 31 May, 2007

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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 bb

c c c c

Future: Stripe rust outlook

• Stripe rust inoculum may be available on winter wheat next spring – scout your fields; check AgAlerts

• Weather dependent– Mild winter– Cool, wet spring

• Scout and apply fungicide early

Stripe rust control• Eliminate green bridge• Use resistant varieties

– plantsciences.montana.edu/crops• If you don’t plant a resistant variety, you may

need to apply fungicide – need 4-5 bu yield gain to pay for the application cost

• If stripe rust is present: Spray between the period of stem elongation and heading – need to protect the flag leaf. Check the preharvest interval on the fungicide label