Isolation, identification and pathogenicity studies of major seed borne pathogens of soybean

Soybean (Glycine max (L.) Merrill) is a leguminous crop originating from East Asia. Botanically, soybean is categorized as an oilseed crop rather than a pulse and is popularly referred as the “golden” or “miracle” crop. Seed borne pathogens constitute a major constraint in soybean cultivation, significantly affecting seed germination and crop establishment. The external seed borne mycoflora, namely Aspergillus niger and Aspergillus flavus, were isolated using the standard blotter method, whereas internal seed-borne mycoflora, including Fusarium oxysporum and Macrophomina phaseolina, were isolated by the agar plate method. Identification of the isolated fungi was carried out based on microscopic observations of their mycelial and spore characteristics, and their pathogenicity was confirmed through the seed inoculation method. Among the seed borne fungi tested, Fusarium oxysporum recorded the highest incidence (93.33%), followed by Macrophomina phaseolina (90.00%), Aspergillus niger (86.67%) and Aspergillus flavus (83.33%).