410 likes | 603 Views
Crop diseases of 2011: Stripe rust. Dr. Mary Burrows. The rusts of wheat. Stripe Stem Leaf . Jim Berg, MSU. Yellow Black Red. Fall infection by stripe rust, 2010. Stripe rust: gen’l WA or Canada . Leaf rust, stem rust:
E N D
Crop diseases of 2011: Stripe rust Dr. Mary Burrows
The rusts of wheat Stripe Stem Leaf Jim Berg, MSU Yellow Black Red
Stripe rust: gen’l WA or Canada Leaf rust, stem rust: ‘Puccinia pathway’
Stripe rust spore cloud: 23 June, 2011 near Kremlin (Hill Co.) Photo courtesy of Ryan McCormick
Montana’s stripe rust epidemic, 2011: why? • Widespread fall infection • Extended fall • Deep, lengthy snow cover • Favorable spring temperatures • Flooding created wet, humid conditions throughout the year • Even after day temps became hot, night temps were favorable for infection (50-70F) • A widely planted, susceptible variety (Genou) • New strains • April: alerts from Xianming Chen that stripe rust was off to an ‘early start’ in WA
Great Falls area, 23 June, 2011 WW Variety: Genou
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
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 Pucciniastriiformisf. sp. triticiin the United States in 2000. Plant Dis. 86:39-46.
New strains are more aggressiveMoon 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”
Reports of stripe rust in Montana 20 June, 2011(Diagnostic lab samples)
Why didn’t the epidemic stop when it got hot? • Stripe rust disease progress is tied to night time temperatures 50 to 70°F Great Falls 1 May to 30 July
Yellowstone Promontory Johnston & Grey, 2006 Stripe Rust: variety resistance is very effective at reducing yield losses Susceptible variety Resistant variety
CDC Falcon Yellowstone
Fungicides Ron Muzzana, 2011
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)
‘Rescue’ spraying? Remember your PHI!
On-farm/on-station fungicide trials: tillering applications (sprayed 9-10 June, rated 7-8 July)
What is this information worth? • Not spraying resistant varieties • ~1 million acres; cost for spray ~$20/A = $20 million • Susceptible varieties sprayed in a timely manner saved ~10bu/A, 1.5 mil. A, $8/bu = $120 million in increased yield – cost of spraying ($20/A) = $90 million • Montana growers spent $15 mil. on fungicide
Acknowledgements Dai Ito, Matt Moffet, Zach Miller, Linnea Skoglund MSU County Extension Agents USPEST.ORG
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
28 July, 2009, Fort Ellis stem rust fungicide trial (22 d after fungicide application, 53 d after pathogen inoculation) Spreader row Triazole + Strobilurin
Yield, stem rust fungicide trial2009, Bozeman d bcdcd cd bcbc bc b a a
Strobilurin fungicides, 14 daa Headline Gem 500 SC
Trizole fungicides, 14 daa Alto Caramba Proline
Strobiliurin + Trizole, 14 daa Quilt Quilt Xcel
Strobiliurin + Trizole, 14 daa Prosaro Twinline
Degree day map, 9 May, 2011First reports from Ronan, Kalispell
Degree day map, 24 May, 2011Reports from Havre, Fort Benton, Great FallsMary: “Genou is what??? Send a sample”
June 1: “Dan/Jeannie (Pondera, Toole Co) – it’s coming your way”