<i>In vitro</i> biocontrol of phytopathogenic bacteria using floral essential oils and their synergistic blends

Chemical compositions of essential oils (EOs) from <i>Pelargonium graveolens</i> (EO-PG), <i>Lavandula angustifolia</i> (EO-LA) and <i>Cananga odorata</i> (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 <i>Xanthomonas citri, X. euvesicatoria, X. vasicola, X. campestris, Pseudomonas fluorescens, Xylella fastidiosa, Burkholderia cepacia, Pantoea ananatis, Pectobacterium carotovorum</i> and <i>Ralstonia solanacearum</i> 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.