Effects of conidial concentration and stigma wetness period on infection by the sorghum ergot pathogenClaviceps africana

Abstract

The effect of conidial concentration and length of stigma wetness period on infection of sorghum spikelets by Claviceps africana was studied in a controlled environment experiment. A spore concentration of at least 106 conidia/mL was required for maximum infection on sorghum panicles. Maximum infection occurred during a stigma wetness period between 4.5 and 6 h. Approximately 11–15% infection occurred when stigmas had been dried immediately after inoculation. This study demonstrated that the stigma wetness is an important parameter in sorghum ergot epidemiology.