Twisted leaves (Flag Smut)

The leaves of diseased plants are often twisted and have long gray or black lesions that run parallel to the leaf veins. As the plants mature, the lesions rupture and release large numbers of black, powdery spores of the fungus. Flag smut may infect all the tillers of a plant, but in some cases, only a few tillers become diseased. The heads of diseased tillers are poorly developed and often will not emerge from the twisted flag leaves.