Methods of field inoculation of sweet corn (Zea mays L.) with Sphacelotheca reiliana (Kühn) Clinton for head smut resistance tests were evaluated. Application of a mixture of teliospores and slightly dampened vermiculite with the seed by means of a V-belt planter was the best method tested and resulted in a 95% disease incidence in the most susceptible cultivar. Application of this mixture by hand in individual planting holes resulted in greater disease incidence but required much more labor and inoculum.
Incidence of head smut caused by Sphacelotheca reiliana (Kuhn) Clinton in sweet corn (Zea mays L.) was decreased by frequent early irrigation (total of 15-20 cm of water during the first 18 to 21 days after planting), compared to no irrigation during the same period. The percentage of infection increased as planting depth increased from 2.5 cm to 7.6 cm. Large seed produced fewer infected plants than small seed, whereas the percentage of infected plants produced from medium-size seed was intermediate.