Bioprospecting of bioactive essential oils against phytopathogenic fungi

Abstract

Diseases caused by fungi pose risks to modern agriculture globally. The most commonly used control is the chemical, but the indiscriminate use of these products causes risks of environmental contamination and of rural workers. In the search for alternative methods of control, essential oils appear, which are natural plant products with antifungal, antibacterial and insecticidal properties, and present less risk to the environment. The objective of this work was to evaluate the in vitro antifungal activity of essential oils on the inhibition of mycelial growth of phytopathogenic fungi. The essential oils of bush avocado (Persea major), rosemary (Rosmarinus officinalis L.), garlic (Allium sativum L.), cinnamom-fire (Cryptocarya aschersoniana Mez.), sassafras cinnamom (Ocotea odorifera Vell.), lemon grass (Cymbopogon citratus), capitiu (Siparuna guianensis Aubl.), India clove (Syzygium aromaticum), guamirim (Myrcia splendens) guava brava (Myrcia tomentosa Aubl.), jatoba (Hymenaea courbaril L.), black peper (Piper nigrum L.), thyme (Thymus vulgaris L.) and annatto (Bixa orellana L.) against fungi Fusarium solani, Pestalotiopsis guepinii, Phytophthora spp., Rhizoctonia solani and Sclerotinia sclerotiorum. The mycelial growth of these fungi was evaluated by means of the Petri dish mycelial growth inhibition index containing the potato, dextrose, agar environment in the concentration of 1,000 μl/mL of the essential oils. The design was completely randomized with three replications. Among the essential oils used, the thyme and India clove promoted complete inhibition of all fungi tested. Garlic essential oil and lemon grass completely inhibited the mycelial growth of three of the five fungi tested. These results demonstrate the importance of the oils for the alternative control of phytopathogens. Key-words: Alternative Control, Mycelial Growth, Medicinal Plants