The conidia are produced profusely during warm, moist weather on corn and small grain residues. Ascospores produced within perithecia are discharged into the air as the fruiting bodies wet and dry during fluctuations in moisture levels. Air currents carry these spores to the flowering spikelets. Ascospores and conidia have been collected in the air above wheat fields, and both are capable of causing infections. The spores germinate in free water on the surface of the spikelet and 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 heads too late in the season to function as secondary inoculum.