Antifungal Activity of Essential Oils from Some Medicinal Plants of Iran against Alternaria alternate

Abstract

Problem statement: Increasing public concern over the level of pesticide residues in food especially fresh produce has built up adequate pressure for scientists to look for less hazardous and environmentally safer compounds for controlling post harvest diseases. Essential oils as registered food grade materials have the potential to be applied as alternative anti-fungal treatments for fresh fruits and vegetables. Approach: We present in this study, the identification of the essential oils with antifungal activity from some medicinal plants of Iran (nettle (Urtica dioica L.), thyme (Thymus vulgaris L.), eucalyptus (Eucalyptus spp.), Rue (Ruta graveolens L.) and common yarrow (Achillea millefolium L.)), and their potential application as "generally regarded as safe" antifungal compounds against Alternaria alternate on tomato as a model pathosystem. Results: Both the nettle and the thyme oils exhibited antifungal activity against A. alternata. The thyme oil exhibited a lower degree of inhibition 68.5 and 74.8% at 1500 and 2000 ppm, respectively. Spore germination and germ tube elongation of the pathogens in potato dextrose broth was strongly reduced in the presence of 1500 ppm of the nettle oil. The same concentration of this oil reduced the percentage of decayed tomatoes. The experiments on reducing the development of natural tomato rot gave similar results. Conclusions: Application of essential oils for postharvest disease control of fresh produce, as a novel emerging alternative to hazardous anti-fungal treatments will allow a safer and environmentally more acceptable management of postharvest diseases.