In order to enhance the efficacy of essential oil of  Aegle marmelos a present study was under taken. The essential oil extract was combined with a formulating agent (coded B+) and named Amaext-eo, bioassayed under in-vitro condition against Pyricularia grisea Sacc. causing blast disease of rice. The Product was found to inhibit conidial germination completely at 0.01% concentration and mycelial growth at 1% concentration whereas, the extract alone could inhibit the germination only partially at the same concentration. The formulated product Amaext-eo retained its fungitoxicity till 24 months storage period in all treatments. In a separate test the efficacy of the product was also assed in the green house and under field condition and compared with the standard fungicide carbendazim. This formulated product has therefore improved the efficacy of fungitoxicity compared to the unformulated botanical extract under in-vitro and in-vivo condition and so found comparable with standard fungicide carbendazim (Bavistin 50%wp).