Relationship between ergot and grain mould development in sorghum (Sorghum bicolor (L.) Moench)

Abstract

A greenhouse experiment was conducted to determine the influence of sorghum ergot on the incidence of grain mould pathogens and on damage to sorghum grains. Grain mould pathogens used were Curvularia lunata, Fusarium subglutinans and Phoma sorghina. Inoculation with the ergot pathogen (Claviceps africana) was performed at anthesis and with the grain mould pathogens at the soft dough growth stage. In all four sorghum cultivars tested, seeds from panicles inoculated with grain mould pathogens following inoculation with C. africana revealed a significantly higher (P*0.05) incidence of P. sorghina than those inoculated with only the ergot or grain mould pathogens. A significantly higher incidence of C. lunata (in PAN8564 and Gambella1107) and F. subglutinans (in PAN8564) was recorded in seeds from panicles inoculated with ergot and grain mould than from the remaining treatments. Likewise, significantly higher grain discolouration was found where both ergot and grain mould pathogens were inoculated on panicles. Relatively lower 1000-grain weight and percentage germination were observed from ergot and grain mould inoculated panicles. There was a significant relationship between ergot severity and the incidence of P. sorghina (r = 0.82 to 0.97, P*0.05) in all the cultivars and that of C. lunata (r = 0.92) in PAN8564. Ergot severity correlated positively (P*0.05) with grain discolouration except in PAN8446. Results indicate that ergot can significantly influence grain mould development and hence the yield and quality of sorghum grains. Management of ergot may thus help to reduce the severity of grain mould thereby decreasing the resulting damage to grains.