Variability of Pathogenicity in Fusarium xylarioides Steyaert: the Causal Agent of Coffee Wilt Disease

Tracheomycosis (or Coffee Wilt Disease) is a vascular disease that causes damage in plantations up to 80% of production in the absence of treatment. The fungus of the disease is Fusarium xylarioides. An experiment in micro-plots was put in place to look for 9 strains of this species from different production regions of the Democratic Republic of Congo (Equateur, Nord Kivu and Province Orientale) in terms of their pathogenicity on coffee Robusta (clone L251). The results from this experiment highlight several levels of pathogenicity significantly different (P ≤ 0.05), and particularly high for aggressive strain Mindembo. The differences do not seem to be related to geographic origins. Mindembo strain, from Equateur, was more aggressive and induces a high mortality (50%). Strains Bunduki and MUCL 45580, originating in Equateur and the Province Orientale, showed high pathogenicity although lower than Mindembo. However, the strain Zobolia (Equateur) multiplies much more slowly and has caused no mortality 3 months after inoculation. This work has important implications for studies on varietal resistance.