Pathogenicity of Fusarium species associated with Bakanae disease of rice in Burkina Faso

Abstract

Contamination of rice seeds by certain Fusarium species is a major problem in achieving food self-sufficiency. The aim of this study was to determine the pathogenicity of Fusarium species associated with Bakanae disease in Burkina Faso. To this end, a pathogenicity test of 17 single-spore isolates belonging to Fusarium chlamydosporum, Fusarium equiseti, Fusarium oxysporum and Fusarium thapsinum species was carried out using the inoculation method by soaking rice seeds of variety FKR 19 in a conidial suspension of 10⁶ conidia/ml. The seeds were then sown in trays containing sterilized potting soil and watered daily. Seedling height and the number of infected seedlings were assessed at day 21 after inoculation (DAI), and incidence rate and severity were determined on the basis of the disease scale. Results showed that the F thapsinum isolate (012-HB-1) caused the greatest elongation of plants with leaf symptoms typical of rice gigantism disease. Seed inoculation with the isolates (F. chlamydosporum, F. equiseti, F. oxysporum) recorded very low incidence rates (0 to 11.82%), reflecting a low capacity to induce disease symptoms, while the F. thapsinum isolate (012-HB-1) showed the highest incidence (88.69%) and severity index (34.35%). Control plants (sterile distilled water) were free from attack, with zero severity. Determining the pathogenicity of the Fusarium species responsible for rice gigantism is useful for developing disease management strategies.