The present study aimed at evaluating the antifungal activities of NECO, ASTOUN and FERCA fungicides based on plants essential oils against Phytophthora katsurae a major constraint in coconut plantations in Ivory Coast. In vitro, the inhibition properties of these fungicides were evaluated at different concentrations 50, 100, 250, 250, 500, 500, 1000, 2000 and 2500 ppm and compared to a synthetic fungicide (phosphorous acid) at 1, 5, 10, 25, 25, 25, 25, 25, 25, 25, 25, 25, 25, 25, 25, 25, 50, 50, 250, 250, 250, 250, 250, 500, and 150 ppm on the radial growth of the mycelium of an isolated pathogen from a diseased nut. The mycelial growth was measured every day during 10 days in the Petri dishes. The results showed inhibition rates ranging from 1.48% to 100%. The biopesticides NECO and ASTOUN were effective against Phytophthora katsurae at 149.14 and 272.38 ppm respectively compared to phosphorous acid. NECO was fungitoxic at 2500 ppm and fungistatic at 1500 and 2000 ppm. Phosphorous acid was simply fungicidal at 150 ppm. Based on these results, these fungicides based on plants essentials oils could be used as biological control of Phytophthora katsurae in coconut plantations in Ivory Coast.