Abstract: The present invention relates to an antifungal oil-in water microemulsion formulation comprising two different bioactive ingredients which are lipophilic (essential oils) and hydrophilic (plant biomass aqueous extracts) in nature, but reside in different phases of the said microemulsion. In particular, the present invention provides a liquid microemulsion comprising a synergistic mixture of two essential oils as the active ingredient in the dispersed phase and a hydrophilic biomass aqueous extract in continuous phase that not only facilitates the overall antifungal efficacy of the microemulsion but also maintains its potency against wilt inducing fungus F. oxysporum during storage.