In vitro biocontrol of phytopathogenic bacteria using floral essential oils and their synergistic blends

Chemical compositions of essential oils (EOs) from Pelargonium graveolens (EO-PG), Lavandula angustifolia (EO-LA) and Cananga odorata (EO-CO) flowers were determined by GC-MS and GC-FID. Antibacterial activities were determined by the microdilution broth method in 96-well culture plates and MIC and MBC values were expressed as mg/mL. EOs were assayed individually and showed to be active against Xanthomonas citri, X. euvesicatoria, X. vasicola, X. campestris, Pseudomonas fluorescens, Xylella fastidiosa, Burkholderia cepacia, Pantoea ananatis, Pectobacterium carotovorum and Ralstonia solanacearum at concentrations between 0.31 and 10 mg/mL. Blend 2 (EO-PG: EO-LA: EO-CO 3:1:1), out of the three blends prepared by this study, was the most promising one since it exhibited the lowest values of MIC and MBC, i.e., between 0.31 and 1 mg/mL. In short, this study showed, for the first time, that EOs and their blends may be promising tools in agricultural defense to prevent severe bacterial diseases in plants.