Stripe rust is rare in Kansas because it requires very cool weather. Leaf rust typically occurs uniformly across a field. In overwintering locations, it is most severe on the bottom leaves. When it blows in from distant fields, it will be most severe on upper leaves. Although some strains of the leaf rust fungus can survive on jointed goatgrass or wheatgrass, they appear to be different from the strains that attack cultivated wheat.
Many rusts have special alternate hosts for completion of the sexual cycle.
However, the sexual cycle on meadow rue apparently does not occur in North America. Therefore, the leaf rust population in the U.S. is composed of distinct races that do not cross with each other. This slows the development of new races because mutation is the only means of genetic change. The leaf rust fungus can only survive in living leaf tissue. It is not soilborne or borne in crop residue.