June 03, 2020

Stripe rust in Western Idaho, 2020

By Dr. Juliet Marshall.

Stripe rust has found its way to western Idaho, reported yesterday (with accompanying picture) on UI Magic CL+ (Oliver Neher).


The growth stage of winter wheat in that area is past the window of fungicide application, and is currently in grain fill.  Spring wheat is still vulnerable and susceptible varieties should be scouted for the appearance of stripe rust.

In the Magic Valley and into eastern Idaho, winter wheat is heading and susceptible varieties are still vulnerable to significant yield loss associated with stripe rust infection.  Stripe rust reaction of last year’s varieties in the Extension Variety Trials is reported in the 2019 Small Grains Report available online.

Please note that while some varieties were reported as resistant in 2019, race changes were reported in California by Dr. Mark Lundy (UC Davis pathologist) in this year’s crop; therefore scouting of all varieties is recommended this season. Please report observations so we can keep track of the in-season spread.

The weather forecast for this and especially next week is very conducive to stripe rust spread and infection.  Fungicide application recommendations developed through NCERA-184 pathologists, coordinated by Dr. Erick De Wolfe Kansas State University, is also attached.