Survival of Colletotrichum sublineolum and other seed-borne fungi in sorghum seeds after twenty months of storage.

Investigations were conducted to determine the longevity of Colletotrichum sublineolum in sorghum seeds. Sorghum grains of fifteen exotic, one local resistant and one susceptible (to anthracnose), genotypes were used for this study. The agar plate and blotter methods were used to isolate pathogens belonging to the species Alternaria, Aspergillus, Cladiosporium, Colletotrichum, Dreschlera, Penicillium at the end of eight months storage period. Depending on the level of contamination, the presence of mycotoxin producing fungi, Alternaria, Aspergillus and Penicillium may reduce the quality of the grains as food and feed materials. Only pathogens belonging to the species Colletotrichum, Curvularia, Dreschlera and Penicillium were isolated at the end of twenty months. Warwarabashi was the only genotype from which Colletotrichum pathogen was isolated, making it an inferior seed material. Warwarabashi had the highest mean seed infection rates of 87 and 56% after eight and twenty months storage, respectively. Initial moisture content of 15% significantly declined to an average of 7 to 8% throughout the storage periods. The result of Blotter test revealed higher seed viability between 52 to 100% when stored for eight months; this decreased significantly (to > 20%) when the storage period is extended to 20 months. One thousand grain weight was also highest (13.6 to 38.4 g), when stored for eight months. The result of this investigation indicates that twenty months storage did not completely eliminate C. sublineolum from sorghum seeds rather it may substantially reduce the pathogen. Long storage of the sorghum grain, however, renders the grains un-suitable as seeds and may also reduce the nutritional qualities. To ensure good establishment of seedlings from such infected seeds, treatment with seed protectants will be essential.