Key Factors Responsible for the Xanthomonas Wilt Epidemic on Banana in East and Central Africa
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Xanthomonas wilt of banana, caused by Xanthomonas campestris pv. musacearum, is a serious threat to sustainable banana production in East and Central Africa. The disease has been confirmed in Uganda, Rwanda, the Democratic Republic of Congo, Burundi, Kenya and Tanzania and is continuing to spread. Surveys were carried out between September 2006 and February 2007 in six countries to determine disease incidence and document the key factors responsible for disease spread. Farmers were randomly selected and questioned to obtain data on cultural production practices, and incidence and awareness of Xanthomonas wilt and other key pests and diseases. Incidence of Xanthomonas wilt was 12% in Kenya, 24% in Burundi, 23% in Rwanda, 16% in Tanzania and greater than 65% in surveyed areas of both Uganda and the eastern Democratic Republic of Congo. The key factors for disease spread are an abundance of susceptible cultivars, a suitable environment for insect vectors, long-distance trade in bananas, lack of knowledge on disease diagnosis and management, and cultural practices that inadvertently spread disease. Over 60% of the respondents across the region indicated that they remove male buds, which can reduce the importance of insect vectors. However, less than 25% debud regularly, and more critically, less than 10% debud with the intention of managing Xanthomonas wilt, except in Uganda where awareness is higher because of a strong extension programme, well funded publicity and farmer training programmes. When establishing new plantings, more than 60% of farmers obtain suckers from their own farm while 30% also get suckers from neighbours. Knowledge of, and access to, clean planting material is a major regional constraint, except in Uganda. Harvesting of green leaves is one of the predisposing practices, especially in Uganda, western Kenya and Tanzania, where leaves are used for cooking and feeding livestock. The perception that Xanthomonas wilt is similar to Fusarium wilt, which complicates diagnosis and slows down the initiation of an appropriate response, has also contributed to disease spread. Banana trade from epidemic zones is an additional factor requiring intervention. Overall levels of knowledge on practices for disease management are low.