Assessment of Potato Bacterial Wilt Disease Status in North Rift Valley of Kenya: A Survey

Abstract

A survey on bacterial wilt (Ralstonia solanacearum) prevalence was carried out in the major potato-growing areas of the North Rift region of Kenya in 2006. Limited information is available on bacterial wilt status in the region. The survey was conducted in Trans Nzoia, Uasin Gishu, Keiyo and Marakwet districts. A questionnaire was administered to 256 potato growers and field observations made in two major potato-growing divisions in each district. The study areas and potato fields were selected based on potato cropping intensity, current potato field size and crop stage. Characteristic plant and tuber bacterial wilt symptoms were the main criteria used to assess the disease. The survey established that potato was grown mainly in pure stand (63%) or in mixed (26%) cropping systems with other crops such as peas, beans, spring onions and maize depending on the area and/or community. Bacterial wilt prevalence varied significantly (p ≤ 0.01) among districts, with the lowest (35%) and highest (99%) in Marakwet and Keiyo districts, respectively. The disease was absent in parts of Marakwet district that are at 2800 m above sea level or higher. Bacterial wilt incidence ranged from 0 to 33% and was significantly different (p ≤ 0.05) among districts. Improper potato and bacterial wilt management practices by most respondents suggested that bacterial wilt has continued unabated due to inadequate farmer knowledge. Factors found to aggravate potato bacterial wilt included indiscriminate use and sourcing of seed, retention of volunteer potato plants, poor field hygiene and lack of management skills on bacterial wilt.