Antifungal activity of essential oils of Lippia species of Colletotrichum sp. in vitro

The pepper (Capsicum annuum L.) is one of the most important vegetable crops grown in Brazil. This culture is greatly affected by plant pathogens, which are known to cause serious economic damage to crops. Among the major diseases of this crop may be mentioned anthracnose caused by Colletotrichum species. This work aimed to investigate the use of different concentrations of oil of Lippia sidoides and Lippia gracilis in control of the in vitro mycelial growth of Colletotrichum sp. Qualitative and quantitative analyses of the essential oils of the species were performed through gas chromatographic systems with mass spectrometer and flame ionization detector. Each essential oil was tested at five different concentrations (0.1, 0.2, 0.3, 0.4 and 0.5 mu L mL(-1)) added to Potato Dextrose Agar (PDA) medium. After ten days of incubation at 25 degrees C and a photoperiod of 12 h proceeded to assessment by measuring the diameters of colonies and percentage inhibition compared to control. The results showed that at concentrations of 0.3 mu L mL(-1), both the essential oils of L. gracilis and L. sidoides inhibited 100% mycelial growth of Colletotrichum sp. According to the results obtained, it can be concluded that the essential oils from plants of the genus Lippia may be an alternative for control Colletotrichum sp., probably due to chemical constituents thymol and carvacrol, as already described with antimicrobial and shown in this study as major components, thymol 42.33 and 4.56% of carvacrol in the oil of L. sidoides and 10% of thymol and 41.7% of carvacrol in L. gracilis. However, more studies should be conducted to further information about the effect of this plant genus and its fungitoxic and fungistatic action on Colletotrichum sp.