Avaliação do potencial antifúngico de óleos essenciais no controle in vitro de um isolado de Colletotrichum brevisporum

Abstract

Anthracnose, caused by species of the genus Colletotrichum, is considered one of the main fungal diseases of passion fruit. In the production of passion fruit crops, some factors present themselves as obstacles, including phytosanitary problems caused by phytopathogens such as viruses, bacteria and fungi. The use of oils, alone or in combination with other methods, could have an important role in controlling phytopathogens, contributing to a reduction in the use of fungicides and, consequently, a lower impact on the environment. Therefore, the present work aimed to evaluate essential oils with antifungal activity for the control of an isolate of Colletotrichum brevisporum. The essential oils of clove, cinnamon, citronella, eucalyptus and rosemary were tested at concentrations of 0% (control), 0.0125%, 0.025%, 0.05%, 0.1% and 0.2%. 5 mm discs of culture medium, obtained from the margin of cultures with seven days of growth, were transferred to the center of the plates containing the different treatments. The controls consisted of inoculating pathogen discs directly into the PDA medium without the addition of essential oils. The plates were incubated in a Biochemical Oxygen Demand (BOD) oven at 25°C and a 12-hour photoperiod. The experimental design was completely randomized with 1 species of Colletotrichum x 5 oils x 6 concentrations, with five replications per treatment. The results obtained for the percentage of mycelial inhibition (PIC) and the mycelial growth rate index (IVCM) were subjected to analysis of variance (ANOVA) and the means compared by the Tukey test, using the statistical program Assistat. Citronella, cinnamon and clove oils were highly effective against the growth of C. brevisporum. The concentrations of citronella oil that promoted 100% control of the pathogen had a fungistatic effect, while the concentrations of cinnamon and clove promoted a fungitoxic effect.