ASSESSMENT OF THREE CASSAVA VARIETIES RESPONSES TO CASSAVA BACTERIAL BLIGHT (CBB) IN THE SEVEN AGRO-ECOLOGICAL ZONES OF COTE DIVOIRE DURING A SURVEY IN 2017

Several cassava varieties are grown in C?te d?Ivoire. Some of them are more widespread than others. Their dissemination depends on characteristics such as yield, taste and dry matter content. Cassava bacterial blight pressure constitutes a threat in all cassava agro-ecological zones. This study aims to survey the widely used varieties and point out the zones where they were more susceptible. The survey took into account the seven agro-ecological zones, the frequency of the varieties presence, the severity index of the disease and the disease incidence. The results showed that three varieties were predominately recorded and are locally known as Akama, Yace and Yavo. Yace was found in all agro-ecological zones. Akama and Yace were abundantly found in the agro-ecological zone 1 and then the agro-ecological zone 4 whereas Yavo was abundantly cropped in the agro-ecological zone 4 and then in the agro-ecological zone 1. Yavo was found more susceptible than Akama and Akama more susceptible than Yace to the disease. The higher rates of severity index and disease incidence were found in the agro-ecological zone 5 and agro-ecological zone 1 for Yavo, the agro-ecological zone 6 and agro-ecological zone 4 for Akama and the agro-ecological zone 6 and agro-ecological zone 1 for Yace, Yace was disease free in the agro-ecological zone 4 and agro-ecological zone 5. Based on these results, it would be necessary to investigate for an efficient control management in order to reduce yield losses due to the high prevalence of Cassava bacterial blight.