In western Kenya, where vitamin A deficiency is common and the white sweet potato is an important secondary staple, orange-fleshed sweet potatoes were introduced and their consumption was promoted, along with other vitamin A-rich foods. Ten women's groups grew a number of varieties of sweet potato on group plots in on-farm trials. Five of the groups also received an intervention consisting of nutritional education, individual counseling, and participatory rapid appraisal techniques to promote vitamin A consumption, while the other five formed the control group that received no additional promotion. Changes in consumption of children under five years of age were assessed before and after a one-year intervention period using the Helen Keller International food-frequency method. Varieties were tested for yield, agronomic performance, taste and appearance, and dry matter content. They were also assessed for β-carotene content in the forms of boiled and mashed puree, sweet potato flour, and processed products. Children in the intervention group consumed vitamin A-rich foods almost twice as frequently as control children (93% more), especially orange-fleshed sweet potatoes, mangoes, dark-green leafy vegetables, butter, and eggs. The yields of orange-fleshed sweet potatoes were at least twice those of white sweet potatoes, as were the taste and appearance ratings. The dry matter content of the varieties exceeded 25%, except for one that was preferred as a weaning food. β-Carotene values were high enough that one cup of boiled and mashed sweet potato fed daily to children of weaning age would alone meet their requirement of vitamin A, even using the higher 12:1 β-carotene:retinol conversion. Orange-fleshed sweet potatoes produced and prepared by women farmers can serve as a key foodbased entry point for reducing vitamin A deficiency.

Potato plays an important role in food security in Kenya but yields are low (<10 t/ha), and this is partly attributed to the lack of healthy planting material. This study is the first wide-scale survey to determine the occurrence and distribution of common potato pests and diseases in Kenyan seed (certified and quality declared) and ware crops. Potato crops growing on 101 farms in 21 districts were examined. Approximately 36% of plants in farmers' fields sampled both during the long rains (main potato-growing season) and short rains seasons displayed virus-like disease symptoms. Six viruses (potato leafroll virus (PLRV), Potato virus A (PVA), potato virus M (PVM), potato virus S (PVS), potato virus X (PVX), and potato virus Y (PVY)) were detected using double antibody sandwich enzyme-linked immunosorbent assay in potato samples. Sequencing of polymerase chain reaction products from PVY-infected plants revealed the presence of recombinant strains of PVY (NTN and Wilga). Four aphid species, Macrosiphum euphorbiae, Aphis gossypii, Myzus persicae, and Aphis fabae, colonized potato in all districts, occurring in greater numbers west of the Great Rift Valley than to the east. There was a positive correlation between virus incidence and aphid numbers in the long rains (main) potato-growing season. PLRV, PVM, PVS, PVX, and PVY were detected in solanaceous weeds. Ralstonia solanacearum was Potato Research (2013) 56:325-342