Stripe rust has been identified in Gallatin, Choteau, and Daniels counties in Montana. Conditions are extremely favorable for stripe rust development in the next week or two, and we may see this disease blow up very quickly. If you have planted a variety known to be susceptible to stripe rust, please scout for symptoms. Symptoms include yellow pustules that occur in stripes (picture at left). Symptoms may be more severe in the bottom of the canopy where there is more moisture. New strains are present in the Great Plains and may overcome previously defined resistance classifications (eg. Jagalene is susceptible to the new strain), but our current classification for winter and spring wheat includes:
Resistant winter wheat varieties include Yellowstone, Promontory, Rocky, Jagalene, Jerry, NuFrontier, and Ledger. Moderately resistant varieties are Rampart, Genou, Vanguard, Wahoo, Hatcher, Genou, Above, Nuwest, Pryor, Morgan, Rocky and Falcon, among others. Moderately susceptible varieties may experience yield losses under severe disease and include Pryor, CDC Falcon, CDC Buteo and Morgan. Highly susceptible varieties including Neeley, NuSky, NuWest, Big Sky and Morgan will need to be sprayed with a fungicide to avoid yield losses if this disease develops. There is less yield benefit from spraying a resistant variety.
Stripe rust can also affect spring wheat. Resistant varieties include Conan and Scholar and moderately resistant varieties include Hank, Freyr, Reeder and Explorer. Highly susceptible varieties include McNeal, NorPro and Fortuna. Varieties rated as moderately susceptible include Outlook, Choteau, Ernest, Kelby and Knudson. A resistant to moderately resistant variety can develop lesions but they are often restricted in their ability to develop and generally do not have to be sprayed.
Barley is susceptible to a different species of stripe rust, the stripe rust affecting wheat will not infect barley. If you see stripe rust on barley please let me know and send in a sample.
If symptoms are seen and the yield potential is high enough to justify a fungicide application, spray a fungicide at the first appearance of symptoms. Most registered products have a 45 day waiting period between application and harvest, so watch your pre-harvest interval according to your crop maturity. Appropriate fungicides include products in either the strobilurin or triazole classes, or combinations of the two chemistries. Fungicide application is appropriate through flowering.
For more information on stripe rust visit: https://wiki.bugwood.org/HPIPM:Stripe_Rust_{4d08edaf359bc2115b18a651716ebd427a137946ddca2143fa23b3ea721061e4}28wheat{4d08edaf359bc2115b18a651716ebd427a137946ddca2143fa23b3ea721061e4}29
For fungicide recommendations:
https://wiki.bugwood.org/HPIPM:Fungicide_table
Contact Mary Burrows, Cropland Diseases, with questions. (406-994-7766)
SOUCE: Plant Diagnostic Information System
Posted by Haylie Shipp
