The status of potato leafroll virus in Kenya.
A survey of potato leaf roll disease conducted in major potato growing regions of Kenya (Meru, Kiambu, Nyamira and Kisii districts) revealed the highest incidence in Kisima location, Timau division of Meru district and an absence of PLRV in leaf-rolled samples from Githongo location of the same district. The lowest incidence was recorded in Kisii district. The virus was detected in the phloem tissues of potato sprouts and leaves by tissue blot immunoassay. The method was simple, rapid and sensitive in detecting PLRV in infected potato plants. In Myzus persicae, the acquisition access period, inoculation access period and the latent period of PLRV, isolated from potato cultivar 'Pimpernel' collected from Tigoni location, Kiambu district, were typical of PLRV. It is suggested that virus control in potato in Kenya can be made more effective by planting virus-free seed tubers and by early treatment with insecticides. Additionally, volunteer plants and alternative hosts should be rogued and destroyed because they serve as sources of virus for subsequent infections.