Comparative Incidence of Fungal Pathogens in Common Bean Seeds from Formal and Informal Sources

Background and Objective: The common bean (Phaseolus vulgaris L.) is the most important grain legume for human consumption and plays a vital role in the livelihoods of smallholder farmers in Tanzania, serving as both a food security crop and a source of income. This study aims to determine the incidence of fungal pathogens in common bean seeds obtained from both formal and informal sources. Materials and Methods: Common bean seed samples were collected from formal and informal sources across six districts in Tanzania’s Southern Highlands. Seed health was analyzed using the standard blotter method under ISTA protocols to detect seed-borne fungi. A total of 72 seed lots were tested, and fungal identification was based on morphological features using microscopy. Infection incidence and frequency were calculated, and data were statistically analyzed using ANOVA and Tukey’s test at 5% significance level. Results: The 22 fungal species, including 18 pathogenic and 4 non-pathogenic fungi. All the 22 fungal species were detected in farm-saved seed samples, 9 in QDS seeds, and only 3 in certified seeds. Farm-saved seeds showed the highest fungal incidence, with a total incidence of 95% for samples collected from Sumbawanga district. The highest incidence of pathogenic fungi in farm-saved seeds was recorded in Kilolo district, with an incidence of 26%. In QDS seeds, the highest incidence was 25.5% in a sample from Mbozi district, while certified seeds had the lowest fungal contamination, with a maximum incidence of 22%. The lowest fungal contaminations in certified seeds as compared to QDS and Farm saved seeds may be attributed to difference in certification requirement in all seed categories where certification is stricter in certified seeds compared to QDS and there is no certification at all done in Farm saved seeds. Conclusion: The farm saved seeds have high risk of fungal contaminations, therefore farmers must be emphasized on the use of quality certified seeds so as to avoid the risk of seed borne diseases in their field and hence improving productivity.