Antifungal Activities of Essential Oils Against Citrus Black Rot Disease Agent Alternaria alternata

Abstract:

Antifungal effects of plant essential oils (Origanum onites L., Thymbra spicata L., Lavandula stoechas L. subsp. stoechas L., Foeniculum vulgare Mill. and Laurus nobilis L.) were investigated in vitro conditions against post-harvest fungal pathogen of Citrus, Alternaria alternata. O. onites and T. spicata essential oils exhibited the strongest antifungal activity against A. alternata by inhibiting completely mycelial growth of A.alternata at 20.0 and 80.0 µg ml-¹ concentrations, respectively. Conidial germination and germ tube elongation of the pathogen was also completely inhibited by O. onites, T. spicata and F. vulgare essential oils used at the minimum concentrations of 10.0 µg ml-1. Light and scanning electron microscopic observations on fungal structures, exposed to volatile phase of themost efficient essential oils, revealed considerable structural deformations such as cytoplasmic coagulation, vacuolations and protoplast leakage. The plant essential oils showing potent fungitoxic efficacies may be recommended as a plant-based preservative in the management of fungal infestation of fruits and vegetables during storage.

Key words:

• Alternaria alternata
• Citrus
• Antifungal effects
• Essential oil
• Postharvest