Biocontrol of cassava root-rot mycopathogens with antimicrobial extracts of wood shavings

ABSTRACT

Cassava (Manihot esculenta Crantz) is an excellent source of calories and a good source of income to both small and large-scale farmers in Nigeria. Cassava root rot is an important disease in different agroecological zones of West Africa, limiting the economic yield of this crop. Three prevalent root-rot mycopathogens (Fusarium oxysporum ACV16, Fusarium solani ACV09, and Aspergillus flavus OCV01) were isolated from freshly harvested cassava through direct plating on Potato Dextrose Agar. F. solani ACV09 was the most virulent, with rot severity of 37.96%. The biocontrol potentials of aqueous extracts of Cola nitida, Gmelina arborea, and Milicia excelsa wood shavings against root-rot pathogens were investigated using the in-vitro mycelial inhibition assay (medium amendment). C. nitida extract, at 0.002 g/mL, had the highest overall inhibitory effect on F. oxysporum ACV16, F. solani ACV09, and A. flavus OCV01, with average mycelial growth inhibition (MGI) of 52.09%, 84.46%, and 78.70%, respectively. G. arborea was most effective against F. solani ACV09, with MGI of 83.50% at 0.002 g/mL. However, F. oxysporum ACV16 appeared to be resistant to M. excelsa wood extract, with mycelial growth inhibition range between 0.69% and 2.08%. Aqueous extracts of C. nitida, M. excelsa and G. arborea wood shavings possess antifungal properties against cassava root-rot pathogens. These plant materials can be considered in the development of efficient biocontrol measures against cassava root-rot diseases, to enhance the production of this economically important crop in Nigeria.

KEYWORDS:

• Biocontrol
• cassava
• mycopathogens
• rot
• wood-extract

Authors’ contributions

The study was a collaborative investigation involving the three authors. Oduwaye, O. F. and Fashola, O. O. contributed to the design, isolation and identification of pathogens, as well as the review of manuscript (conceptualization, investigation, and review). Adedire, O. M. conducted the inhibitory assay (methodology), result analysis and wrote the first draft of manuscript. Authors read and approved the final manuscript.

Disclosure statement

Authors have declared that no competing interests exist.