Distribution of fusarium wilt and the populations of Fusarium oxysporum f.sp. cubense on bananas in Uganda
2001
Kangire, A. | Rutherford, M.A. | Gold, C.S. (Kawanda Agricultural Research Inst., P.O. Box 7065, Kampala (Uganda)
The distribution of Fusarium wilt of bananas, caused by Fusarium oxysporum f.sp. cubense (FOC), was assessed at 24 sites in Uganda in 1995, by observation of characteristic external and internal symptoms, complemented by farmer interviews. The disease was encountered at 19 out of the 24 sites during the survey. Fusarium wilt has since been observed on bananas at other locations outside the original survey sites confirming disease presence in most of the primary banana growing areas in the country. The number of affected farms at each site was variable with erratic distribution of the disease within farms. Incidence was highest at lower altitudes compared with higher altitudes suggesting a temperature response. The disease exclusively affected recently introduced cultivars (exotic), i.e. Gros Michel (Bogoya, AAA), Pisang Awak (Kayirja, ABB) and Ney Poovan (Sukari-Ndiizi and Kisubi, AB). East African highland bananas (AAA-EA), Bluggoe (Kivuvu, ABB), plantains (Gorja, AAB) and Cavendish (AAA) were not affected by the disease. Pathogenicity tests using differential cultivars confirmed the presence of race 1 of FOC while races 2 and 4 were not detected. Absence of race 2 previously reported in Kenya and Tanzania and race 4 were not detected. Absence of race 2 previously reported in Kenya and Tanzania and race 4 has significant implications on application of quarantine measures to control the disease in the region. Identification of populations of FOC using vegetative compatibility testers confirmed presence of four (4) vegetative compatibility groups (VCG), namely: 0124, 0124/125, 01212 and 01222, which were also widely distributed. Some of these VCGs were compatible with those from South East Asia which is thought to be the center of origin of Musa sp. Compatibility of some VCGs with those from South East Asia confirmed as genetic relationship of the origin of FOC populations in Uganda
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