Abstract: Background and Objective: Cassava (Manihot esculenta Crantz) is an important crop in intertropical areas. However, it is subject to many diseases, among them the bacterial blight caused by Xanthomonas axonopodis pv. manihotis. The objective of this study was to assess the behavior of two varieties of cassava, including a traditional one (Diarrassouba) and an improved one (Bocou 1) in the area of Ferkessédougou endemic to bacterial blight and on the other hand, to test the bactericidal activity of NECO, a biological product made of essential oil extracted from Ocimum gratissimum. Materials and Methods: Eight increasing concentrations of NECO in comparison with the reference Callicuivre were used to assess the in vitro antibacterial activity and the 5 mL L–1 NECO dose was used in situ. Data were analyzed with one way ANOVA and Statistica software. Results: The results show that NECO exhibits bacterial inhibitory activity with diameters ranging from 0.34-3.46 cm. In situ, the use of NECO at 5 mL L–1 dose significantly decreases bacterial blight in the range of 74.94-59.35%, depending on the crop season. Conclusion: NECO could, therefore, be used as an alternative to synthetic products in cassava bacterial blight control.