Scout, but do not spray, for stripe and leaf rust in the fall--leastwise, not in Colorado. That's the recommendation from Kirk Broders, Colorado State University plant pathologist.
It is important to scout fields for rust in the fall, but do not apply fungicide in the fall, he says. Instead, these fields should be noted and scouted early in the spring for the presence of active sporulation of stripe rust. If stripe rust appears on wheat in the fall, and there is consistent snow cover through the winter, the stripe rust pathogen has the ability to overwinter in Colorado, as was observed in a few locations in 2015-16. If there is active sporulation in the spring an early fungicide application is recommended to prevent further spread of the pathogen.