Status of Fusarium Wilt of Banana in Kisii County and Its Management Using Soil Amendments

Abstract

Fusarium wilt is a serious problem in banana growing regions in Kenya. It affects particularly apple bananas but other bananas such as Gros Michel and Bokoboko are also affected to a lesser extent. Improving the conditions of the soils is one of the key control methods as the Fusarium oxysporum is widespread in the soils that have high moisture content and poor drainage. The objective of this study was to determine the extent of spread of Fusarium wilt of banana in Kisii County and the efficacy of organic and inorganic soil amendments in the management of the disease. A semi structured questionnaire was administered to individual farmers in agro-ecological zones UM1 and LH1 in the form of interviews to establish the spread of Fusarium wilt. During the survey, banana cuttings of pseudo stem and roots of four symptomatic and four asymptomatic banana samples from each farm were taken and used in isolation of Fusarium wilt pathogen. The soil amendments that were evaluated were wood ash, Tithonia diversifolia, poultry manure, diammonium phosphate, urea and sodium hypochlorite. Inoculum was prepared in the laboratory using the collected diseased banana samples and then used to infest soils both in the greenhouse and the field on potted plants. The greenhouse trials evaluated apple bananas only whereas the field trials evaluated susceptible, tolerant and resistant banana varieties. Majority of the farmers 55% attained an average of eight years education and were in age bracket of 40-50 years. Commonly grown crops by the farmers in the two Agro-ecological zones were bananas, coffee, maize, tea. While many of the farmers grew apple banana as one of the improved banana varieties in both sites, 95% of the respondents in LH1 and 55% in UM1 grew Ng’ombe,atraditional variety. Ng’ombe was the most popular local variety grown in both agro-ecological zones giving 75% of the total respondents’ while100% and 90% of the respondents gave apple variety and Uganda green respectively as the main improved/exotic banana varieties

in the two zones. Farmers listed diseases such as Fusarium wilt of bananas and Black sigatoka as the main constraints affecting bananas. The results indicate significant reduction in disease incidence in plots treated with poultry manure and sugarcane ash. The Fusarium wilt incidence increased overtime in all the treatments but at different rates with control plots recording the highest incidence every week from the start to the end of sampling time while the least incidence was noted in plots treated with sugarcane ash. The highest Fusarium wilt incidence and largest area of disease progress curve (AUDPC) was observed in plots without any soil amendment applied. The experimental results from this study identified poultry manure and sugarcane ash as the most active organic amendments against Fusarium wilt, reducing disease incidence by over 30% compared to other amendments. Total suppression is significant in the management of the disease since the pathogen is soil borne and can last for long; however, this was not achieved by any of the amendments. In summary, soil amendments can be used to practically manage Fusarium wilt and poultry manure and sugarcane ash present good management strategy that should be integrated in Fusarium wilt management to reduce the inoculum levels and pathogenicity. Based on the findings of this study, further studies should be done in the field in different soil types, banana cultivars and crop husbandry systems to determine the synergistic effect of integrating poultry manure and wood ash in in management of Fusarium wilt under field conditions.