CULTURAL CHARACTERIZATION OF FIVE ISOLATES OF FUSARIUM OXYSPORUM F. SP. CUBENSE (BANANA FUSARIUM WILT) AND ANTIFUNGAL ACTIVITY OF PLANT EXTRACTS

Abstract

Plantain (Musa spp.) is one of the most important food crops in Cameroon and elsewhere in Central and West Africa. However, its production is threatened by many diseases, including banana Fusarium wilt. The objective of this work was to contribute to the improvement of plantains production through the assessment of the behavior of the pathogen isolates to some environmental factors and the biological management of Fusarium wilt in Lab conditions. To achieve this, roots and leaves samples were collected from infected plantain plantations in five divisions of the West Region of Cameroon and brought to the laboratory for isolation and identification of the pathogen. Then, the pathogenicity test was carried out and the optimal growth conditions of Fusarium oxysporum f. sp. cubense (FOC), were evaluated on three culture media (V8, PDA and Banana Leaf Extract Dextrose Agar), five pH (5, 6, 7, 8 and 9) and two temperatures (18 and 25°C). Finally, antifungal activities of aqueous and ethanolic extracts of Callistemon viminalis and Chenopodium ambrosioides were evaluated on the growth of the five isolates (FOC-DSC, FOC-BAL, FOC-FBT, FOC-BAN and FOC-KEK) at 7.5 mg/mL and 15mg/mL. The results showed that all the five isolates were pathogenic. However, the isolates from Foumbot (FOC-FBT) and Kekem (FOC-KEK) were more aggressive. The V8 and BLEDA media at the pH 6 and 25°C were more suitable for the growth of all the isolates of FOC. The efficiency of ethanolic extract of C. ambrosioides was significantly comparable to the chemical fungicide (Eagrow Care) at 15mg/mL. Isolates of the Fusarium wilt pathogen in the West Region of Cameroon are phenotypically different and due to the efficiency of the ethanolic extract of C. ambrosioides, it may be exploit for its antifungal properties on the management of the disease.