Cassava Bacterial Blight Development in the Agro-Ecological Zones of Cote D’ivoire

Abstract

Cassava growth in Côte d’Ivoire is affected by the variation of climatic parameters and Cassava Bacterial Blight (CBB). CBB is a destructive disease influenced by climatic conditions which can lead to 100 % yield loss. For a better management of CBB in the context of climate change/variability, it was essential to study the evolution of the disease under different agro-ecological zones in Côte d’Ivoire. For this purpose, surveys were conducted out in cassava fields from 2014 to 2017 in the seven agro-ecological zones of Côte d’Ivoire and the varieties were assessed under natural and artificial conditions. Farmers’ knowledge on both climate change and CBB were also assessed. The results showed a prevalence of the disease in the agro-ecological zone 6, the agro-ecological zone 4 and the agro-ecological zone 1 with dieback incidence under extreme and favourable conditions. Cassava farmers interviewed were able to identify changes occurred in climate, their characteristics and their impacts on cassava. However, cassava bacterial blight was unknown by the majority. Three varieties were predominately recorded and are locally known as Akama, Yace and Yavo. Yavo was found more susceptible than Akama that was more susceptible than Yace to the disease. Cassava varieties are susceptible to the disease at different rates in the different agro-ecological zones. However, some of them appeared to be more tolerant than others. Climatic conditions constitute one of the major constraints to cassava cultivation in Côte d’Ivoire and are aggravating cassava bacterial blight expression. Therefore, the losses related to CBB remains unpredictable. All these aspects should be considered in the selection of tolerant varieties across different agro-ecological zones. It is therefore urgent to implement control strategies in response to the varying climatic conditions to prevent and reduce the impacts of both the variation of climatic parameters and the disease.