The combined effect of the antagonistic yeasts Rhodotorula aurantiaca LMA1, Rodothorula glutinis LMS andPichia anomala CC-2 and silicon (Si) was evaluated in relation to the control of bacterial fruit blotch (BFB)caused by Acidovorax citrulli in seedlings and plants, and possible mechanisms of action involved in thecontrol were analyzed. The incorporation of 1.41 g Si kg−1(calcium silicate) into the substrate, togetherwith foliar spraying with yeast (1.5 × 107cells mL−1) and foliar spraying with 17 mM Si (potassium sil-icate) and the yeasts, separately or in combination, reduced the severity of the disease and protectedseedlings and plants. These plants were inoculated with A. citrulli by foliar spraying (3.4 × 107UFC mL−1)24 h following the treatment. However, no additive or synergistic effects of the combined treatmentswere observed. The spraying of LMA1 + Si and LMA1 resulted in the highest levels of control of BFB inplants, and this level of control was higher than that provided by acibenzolar-S-methyl. Foliar sprayingwith LMA1 and Si, either separately or in combination, protected melon plants from infection by A. citrullifor 29 days. Increases in the activity of polyphenol oxidase after foliar spraying with Si and LMA1, andincreases of ascorbate peroxidase activity after foliar spraying with LMA1 + Si and LMA1 are likely relatedto the induction of resistance to BFB.