Seed potato systems in East Africa are described and opportunities for improvement identified on the basis of interviews with potato producers in Kenya, Uganda and Ethiopia, and an assessment of Ralstonia solanacearum and virus disease levels in Kenya. 3% of seed potato sold in Kenyan markets was virus free. Ralstonia solanacearum was found in 74% of potato farms. Less than 5% of the farmers interviewed source seed potato from specialized seed growers. Over 50% rely entirely on farm-saved seed. Current seed potato prices justify this behavior. To improve the system the local and specialized chain need to be tackled simultaneously. To improve the local chain ware potato farmers require training on seed quality maintenance and managing bacterial wilt and viruses. Research into virus resistance and the effect of mixed virus infection on yield deserves attention. Private investment in seed potato production could increase volumes produced and reduce prices.Resumen Se describen sistemas de semillas de papa en África del Este y se identifican oportunidades de mejora basándose en entrevistas con productores de papas en Kenia, Uganda y Etiopía y una evaluación de los niveles de las enfermedades causadas por Ralstonia solanacearum y virus en Kenia. El 3% de la semilla de papa vendido en los mercados de Kenia estaba libre de virus. Se encontró Ralstonia solanacearum en 74% de las explotaciones agrarias de papa. Menos del 5% de los agricultores entrevistados obtienen semillas de papa de agricultores especializados en semillas. Más del 50% dependen totalmente de las semillas almacenadas en la explotación agraria. Los precios actuales de semilla de papa justifican este comportamiento. Para mejorar el sistema, se debe abordar simultáneamente tanto la cadena local y la especializada. Para mejorar la cadena local, los agricultores de papa para consumo humano necesitan capacitación sobre el mantenimiento de la calidad de la semilla y manejo de la marchités bacteriana y virus. La investigación sobre resistencia a los virus y el efecto de la infección de mezcla de virus sobre el rendimiento merece atención. La inversión privada en la producción de semilla de papa podría aumentar los volúmenes de producción y reducir los precios.

In Kenya, seed potato quality is often a major yield constraint in potato production as smallholder farmers use farm-saved seed without proper management of seed-borne pests and diseases. Farm-saved seed is therefore often highly degenerated. We carried out on-farm research to assess whether farmer-managed positive seed selection could improve yield. Positive selection gave an average yield increase in farmer-managed trials of 34%, corresponding to a 284-€ increase in profit per hectare at an additional production cost of only 6€/ha. Positive selection can be an important alternative and complementary technology to regular seed replacement, especially in the context of imperfect rural economies characterized by high risks of production and insecure markets. It does not require cash investments and is thus accessible for all potato producers. It can also be applied where access to highquality seed is not guaranteed. The technology is also suitable for landraces and not recognized cultivars that cannot be multiplied formally. Finally, the technology fits seamlessly within the seed systems of Sub-Saharan Africa, which are dominated by self-supply and neighbour supply of seed potatoes.

Vegetatively propagated crop (VPC) seed tends to remain true to varietal type but is bulky, often carries disease, and is slow to produce. So VPC seed needs to be handled differently than that of other crops, e.g., it tends to be sourced locally, often must be fresh, and it is less often sold on the market. Hence, a framework was adapted to describe and support interventions in such seed systems. The framework was used with 13 case studies to understand VPC seed systems for roots, tubers, and bananas, including differing roles and sometimes conflicting goals of stakeholders, and to identify potential coordination breakdowns when actors fail to develop a shared understanding and vision. In this article, we review those case studies. The framework is a critical tool to (a) document VPC seed systems and build evidence; (b) diagnose and treat coordination breakdown and (c) guide decision-makers and donors on the design of more sustainable seed system interventions for VPCs. The framework can be used to analyze past interventions and will be useful for planning future VPC seed programs. ARTICLE HISTORY

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