Impact of Essential Oils on Growth of Phytopathogenic Fungi Responsible for Rotting of Fruits

Aims: To evaluate the antifungal activity of essential oils against phytopathogenic fungi for control of post harvest diseases.

Place of Study: present study was carried out at Department of Botany, Rajiv Gandhi University, Itanagar, India.

Methodology: Phytopathogenic fungi were isolated from infected fruits on rose Bengal agar medium and potato dextrose agar medium. Subsequently fungi were identified and cultures were maintained on the above mentioned medium. Essential oils were extracted from a number of plants and further four plants (Acorus calamus, Agreratum conyzoides, Artemisia nilagirica, Litsea cubeba) essential oils were selected to evaluate their essential oils against the isolated fungi. Antifungal activity was assessed by poisoned food technique using above mentioned media. Essential oils were standardized for fungitoxic properties and nature of toxicity. Fungitoxic spectrum of essential oils was also determined using other storage fungi.

Results: Antifungal property of essential oils was determined at different concentration such as 125 ppm, 250 ppm, 500 ppm, 1000 ppm and 5000 ppm. There was 100% inhibition in the growth of phytopathogenic fungi at 5000 and 1000 ppm concentration by essential oil of Acorus calamus, Agreratum conyzoides, Artemisia nilagirica and Litsea cubeba. Essential oil of Acorus calamus and Agreratum conyzoides also inhibited growth of Alternaria alternata and Botrytis cinerea at 500 ppm concentration. The decrease in colony diameter or growth of fungus was corresponding to the concentration of oil. Minimum inhibitory concentration of oils was reported 500 ppm. Essential oils of Agreratum conyzoides, Artemisia nilagirica and Litsea cubeba were fungicidal at 1000 ppm concentration. A. calamus oil was found fungicidal at 500 ppm for A. alternata and B. cinerea and at 1000 ppm for fungi Fusarium oxysporum and Penicillium expansum. Fungitoxic spectrum of oils showed that there was almost 100% inhibition of all the other storage fungi.

Conclusion: On the basis of results It can be stated that Acorus calamus, Agreratum conyzoides, Artemisia nilagirica and Litsea cubeba essential oil may be used as botanical pesticides for management of post harvest phytopathogenic fungal diseases. However, further investigations are needed in light of pharmacological tests.