Thus, in Benin, systemic infection was most severe in the SS, followed by the SGS, the NGS and the FSM zone where in 60, 57, 30 and 25% of sites (percentage data not shown), respectively more than half of the plants were systemically infected, corresponding to incidence classes 4 and 5. Sites with a systemic infection incidence of 90–100% of plants (incidence class 5) were observed in each ecozone. Statistical analysis of the incidence—plants in symptom classes 2–5—of the disease by ecozones revealed significant differences (Table 1): disease incidence was lower in the FSM zone than in the SGS and the SS of Benin. Nevertheless, 36% of infected plants (classes 2–5) in the FSM zone showed dieback symptoms (class 5). In the NGS, CBB incidence was lower than in the SGS (P=0.087) and the SS (P=0.075). The incidence was 100% in large governmental cassava multiplication farms in North Benin.