摘要：Bacterial wilt (caused by Ralstonia solanacearum ) has spread to all potato growing areas in Kenya, affecting over 70% of potato farms and causing yield losses of between 50 to 100%; it is followed by late blight affecting 67% and viral diseases (12%). The disease was first reported in Kenya in 1945 around the Embu area from where it spread to other parts of the country. The disease is believed to have been introduced with tuber seeds imported from Europe. In potatoes, the bacteria is tuber borne and is primarily disseminated through infected seed tubers. It is further spread through infected run-off water or soil adhering to tools and shoes. Infected seed tubers from bacterial wilt infested areas have mainly contributed to the spread of the disease to many potato producing areas in Kenya; this is mainly a consequence of the informal potato seed system prevalent in the country. Because the country produces less than 1.1 % of her national certified seed requirement, most farmers are forced to plant seeds from informal sources such as farm-saved (self supply), local markets or neighbours. The certified seeds are also highly priced thereby discouraging most small scale farmers from using them. Although most farmers have been trained on production of clean seed from basic or certified seeds on their farms, such seeds (known as Quality Declared Seeds) are not recognised by the Kenyan law and their trade is illegal. With no option, potato growers continue using planting material from informal sources. With informal sources, seed quality cannot be assured. The situation is worsened by the uncontrolled and/or illegal cross border trade. In addition to the prevalence of informal seed systems, farmers are unaware and/ or are unable to apply affective measures for the control of bacterial wilt. From the foregoing, it is unlikely that bacterial wilt of potatoes will ever be tamed in Kenya. Unless all stakeholders tackle the problem collectively, the blame game will continue.
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