Antifungal Activity of Nettle (Urtica dioica L.) and European Pennyroyal (Mentha pulegium L.) Extracts on Alternaria alternata

Increasing public concerns about fungicide residues have prompted interests in biological control especially use of herb extracts derived from several medicinal plants as an alternative strategy for disease management. Recently tomato leaf spot disease caused by Alternaria alternata has become epidemic in almost areas of Iran. This study was conducted for the identification of the effect of antifungal activity of two medicinal plants extracts; Mentha pulegium L. and Urtica dioica L. against A. alternata. Both plant extracts exhibited antifungal potential against the pathogenic fungus. The Nettle extract showed a more degree of inhibition with 59.78% and 77.81% inhibition rate at concentration of 1000 and 1500 ppm, respectively. The inhibition of the mycelial growth was strongly reduced in the concentration of 1500 ppm of both plant extracts. The results of this study confirm that extracts of the selected medicinal plants can be used as an alternative fungicide in control of this pathogenic fungus.