Stem Rust Stem rust causes dark orange pustules on the stems and also on the leaves. It is similar to leaf rust, but leaf rust does not attack the stems. Stem rust can cause serious losses because the stem can be completely girdled by the pustules and prevent grain fill. Stem rust spores usually blow into Kansas from the south late in the growing season. If the stem rust arrives early, losses are higher.
Most varieties now have adequate resistance to stem rust, but a few are moderately susceptible.