Stripe Rust Update
Stripe Rust was confirmed in the Magic Valley with three fields of Brundage showing stripe rust infection south of the Kimberly exit off of Hwy 84. Upper leaves were infected, indicating the occurrence of a recent spring infection, not an overwintering event. All three fields were sprayed with a fungicide to control the infection.
Brad Brown, Extension Soil and Crop Management Specialist in Parma, has found stripe rust in spring wheat at the Parma research station. The infection was minor with less than 1% of plants infected and only one small stripe on any infected leaf. The wheat plants were past flowering and no control was warranted.
In Northern Idaho, Doug Finkelnburg provided the first report of stripe rust found Monday June 4 in Latah county on the Parker Farm, found at low levels in susceptible varieties. Forecasted weather for the upcoming week is for conditions conducive to the infection and spread of stripe rust all across the state. The weekend forecast is for a return to warmer than average conditions, which is not conducive to stripe rust development.
All other reports of stripe rust in southern and eastern Idaho have not been confirmed. There are several fields of winter wheat with yellowing of upper canopy leaves that have been attributed to root rot issues such as Rhizoctonia and Strawbreaker eyespot. This has been in heavily seeded, fertilized and irrigated fields where the lack of air movement and moist conditions have promoted anaerobic conditions at the base of the plant.
Extensive scouting by numerous people have not resulted in any additional stripe rust being found. Thanks to all those who have reported their findings!
Juliet Marshall Associate Professor of Agronomy and Cereals Cropping Systems at the University of Idaho, does not recommend fungicide application at this time, except for spring wheat varieties known to be very susceptible to stripe rust. If still practical, fungicides could be applied with herbicides. However, in general Marshall would not be putting on a separate fungicide application until stripe rust is confirmed in your area and you are growing a susceptible variety. The current threat has now moved to spring wheat. Winter wheat is at heading to flowering with very little to no visible disease.
Additional information and pictures are available on the Cereals Extension website for southern and southeast Idaho: http://www.extension.uidaho.edu/scseidaho/disease/disease_index.htm.