In vitro Antifungal Effects of Various Essential Oils against Aspergillus Crown Rot of Peanut

Abstract

Synthetic fungicides that combat plant pathogenic fungi can enhance crop yields, ensuring stable crop production and market quality. However, the increase in the use of fungicides has led to the development of fungicide-tolerant pathogen strains and the accumulation of fungicide residues in the food chain above safe limits. This underscores the need for improved fungal disease management through alternatives to synthetic fungicides. These alternatives include plant-derived compounds such as essential oils and extracts. Essential oils are known to be potent antifungal activity against both human and plant pathogens. Aspergillus niger is a toxin-producing fungal disease agent that causes Aspergillus crown rot in peanuts. In this study, the antifungal activities of nine different essential oils (EOs) from Foeniculum vulgare, Lippia citriodora, Origanum majorana, Origanum minutiflorum, Origanum onites, Origanum syriacum, Origanum vulgare, Salvia aramiensis and Thymus syriacus plants were evaluated against Aspergillus niger under in vitro conditions. These essential oils were assessed based on their impact on the mycelial growth of A. niger. The spore suspension of the fungus was spread on PDA medium, essential oils were absorbed into antimicrobial sensitivity test discs and their antifungal activities were determined. Among the nine essential oils tested, O. vulgare EO exhibited the highest antifungal activity with an inhibition zone diameter of 49.33 mm. The essential oils of T. syriacus, O. onites, O. syriacum and O. minutiflorum, however, expressed antifungal activity at the relatively lower diameter of inhibition zone (48.67, 47.00, 46.33 and 43.33 mm, respectively). The results of this study indicate that plant essential oils could be valuable in promoting research aimed at developing new agents for fungal disease management. However, further analyses are needed to optimize in vivo application conditions against A. niger.