Aim/background: This study made it possible to assess the importance of Fusarium wilt of cotton in Côte d'Ivoire, through its distribution and the level of pathogenicity of populations of the pathogen. One of the factors limiting cotton production in Côte d'Ivoire is Fusarium wilt, a disease caused by the fungus Fusarium oxysporum f.sp. vasinfectum.
Methods: The fungal material obtained from samples of cotton plants showing symptoms of Fusarium wilt in the field was used for the root dip inoculation test to evaluate the level of virulence of the twenty-four (24) isolates representative of our collection.
Results: This evaluation showed a diversity of aggressiveness within the pathogen population. Indeed, the dendrogram of pathogenicity classes highlighted three clusters. Cluster 1 composed of seven (7) isolates (AM 96, AM 16, AM 47, AM 72, AM 55, AM 81, AM 105) or 29.17% is more virulent with an average wilting index (WI) of between 36.33 and 61 and average stunting index (SI) from 52.33 to 86. Cluster 2, composed of twelve (12) isolates, i.e. 50% of the study isolates (AM 3, AM 48, AM 74, AM 75, AM 28, AM 98, AM 97, AM 33, AM 2, AM 20, AM 12, AM 79) with intermediate virulence and whose average WI is between 5.33 and 26.33 and the SI is between 42.66 and 80.33. Finally, cluster 3 composed of isolates AM 9, AM 90, AM 61, AM 116, AM 94 is less virulent with average wilting and average stunting indices between 0 to 22.33 and 18.66 to 32 respectively.
Conclusion: These results show a strong presence of Fusarium wilt in the south of the cotton basin, but also its continued spread towards areas not traditionally affected and a diversity in the level of pathogenicity of pathogen populations of the Fusarium oxysporum f.sp. vasinfectum.
Key words: Vascular Fusarium wilt, distribution, Fusarium oxysporum f.sp. vasinfectum, pathogenicity, Côte d’Ivoire.
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