Rust spots are very small, circular or elongated, and are vivid orange-red in colour. Leaf rust lesions are mainly found on upper leaf surfaces. They may also occur on the leaf sheath but do not penetrate the stem tissue. Winds can carry rust spores for great distances. The disease can develop rapidly at temperatures between 11-22ºC (52-72ºF) when adequate moisture is available. When heavily infected, the whole leaf will die.
Leaf rust pustules are dusty-yellow to bright-orange, small round to oval spots that are found on the leaves and sheaths. Leaf rust pustules are nearly round and much smaller than those of stem rust. As the plant matures, the rust pustules darken and may appear black.
Choose resistant varieties. Please note that varietal resistance tends to break down over time as new rust strains emerge. Early seeding may help to reduce severity of the disease. Foliar fungicides are effective.