Symptoms
Small raised reddish-brown to cinnamon pustules scattered on both leaf surfaces that release powdery spores when rubbed. Heavy infection yellows and dries the leaves, reducing grain fill.
Prevention
Plant resistant hybrids and avoid late or staggered plantings that bridge the pathogen. Space plants for airflow and remove volunteer host plants nearby.
Treatment
Organic
Spray sulphur or a neem-oil formulation at first pustules. Remove the most heavily infected lower leaves to slow spore build-up.
Chemical (last resort)
Apply a triazole (e.g. tebuconazole) or strobilurin fungicide when rust first appears, repeating per label. Rotate groups to avoid resistance and observe PHI.
Affects 1 crop
Sources
MARDI Corn Production Guide; DOA IPM Manual