Common rust—Puccinia sorghi
Common rust causes pustules that may appear on any aboveground part of the corn plant but they are most
abundant on leaves. The pustules, which may erupt and become powdery, occur nearly simultaneously on both
leaf surfaces. They are golden brown to cinnamon brown, becoming black as the spores mature.
Common rust is favored by cool temperatures and high humidity or overhead sprinklers. Use furrow or drip
irrigation. Generally, fungicides are not required. Some resistant varieties may be available.
pustules on corn leaves