Evaluation of antifungal efficacy of Alternaria alternata on Colletotrichum graminicola

Anthracnose caused by Colletotrichum graminicola is one of the diseases impacting on the yield of sorghum in Nigeria. This study was carried out to evaluate the antifungal efficacy of Alternaria alternata on C. graminicola. The fungi were isolated from anthracnose infected sorghum leaf and cultured on Potato Dextrose Agar. They were identified morphologically by conidia and colony structures. Antagonistic effect of A. alternata against C. graminicola was carried in vitro on PDA using single and dual culture technique. Secondary metabolites were extracted from methanolic extracts of A. alternata and characterized using gas chromatography-mass spectrometry analysis. The antifungal effect of methanolic extract (0.5, 1.0 and 2.0 mg/ml) of A. alternata against C. graminicola was carried out in vivo in the screen house. The results show Twelve bioactive compounds synthesized by A. alternata were characterized according to their peak area, retention time, molecular and molecular weight. Also, 2.0 mg/ml methanolic extract of A. alternata significantly reduced anthracnose incidence and severity in sorghum. The results of this study revealed that methanolic extracts of A. alternata could be used in the management of sorghum anthracnose, probably due to the presence of secondary metabolites