One or more spikelets may be infected, or the entire head may be diseased. Several days after infection masses of pink to salmon-colored spores and mycelium may form on the margin of the glumes of individual spikelets, especially near the base of the kernel. Infected kernels are generally shrunken, wrinkled, and light in weight, with a rough, scabby appearance. These kernels range in color from light-brown to pink to greyish white. The scab fungi overwinter and survive between crops in infected grain and grass stubble, chaff and cornstalk residue left on the soil surface invade the flower.
Infections are most serious when the anthers are exposed during flowering.
Within 7 to 10 days after infection, salmon-pink masses of conidia form at the base of the diseased spikelets. These conidia can be blown by the wind to the heads of other cereal or grass plants producing new secondary infections. This process continues to be repeated as long as the spikelets are susceptible and moist weather prevails. Secondary infections may occur from long distance spread of air borne conidia. Ascospores are usually produced on the head too late in the season to function as secondary inoculum.