Antifungal efficacy of garlic (Allium sativum L.) on selected crop seed-borne fungi

Abstract

This study aimed to assess the inhibitory effectiveness of garlic products on fungi associated with cowpea, sorghum, maize, and groundnut seeds. The in-vivo evaluation involved a seed culture bioassay treated with garlic aqueous extract, while the in vitro antifungal activity of the extract on the radial growth of isolated fungi was determined using the agar well diffusion method. The treatments included garlic powder, garlic paste, garlic powder + molasses, garlic aqueous extracts at 100%, garlic aqueous extracts + adjuvant, and Thiram® (a synthetic fungicide). On untreated cowpea seeds, Aspergillus niger was the most frequently isolated fungal species, with an incidence of 61.5%. Cowpea seeds treated with 100% garlic extracts showed zero incidence of fungal colonies, whereas sorghum seeds + garlic aqueous extract displayed only A. niger. The in vitro study revealed that the inhibitory effect of 100% garlic aqueous extracts + adjuvant on the radial growth inhibition of A. niger, A. flavus, and P. chrysogenum was 78.86%, 70.40%, and 67.36%, respectively. In contrast, the inhibition by garlic powder + molasses and the control was significantly lower (p≤0.05) than other treatments. In conclusion, this study suggests that garlic extracts could be a potential source of organically-based natural fungicides for safeguarding crop seeds.