CBN-V Video Archives - S8-15
Effect of Cassava Mosaic Geminiviruses on Growth and Yield of a Susceptible Cassava Cultivar in Uganda

Owor B.¹, J.P. Legg¹, G. Okao-Okuja¹ and M.W. Ogenga-Latigo²

1. International Institute of Tropical Agriculture- Eastern and Southern Africa Regional Center, P. O. Box 7878, Kampala, Uganda iitanam@infocom.co.ug
2. Makerere University, P. O. Box 7062,Kampala, Uganda

        Cassava mosaic virus disease (CMD) is currently the most important constraint to cassava production in Africa. CMD is caused in Africa by a number of cassava mosaic geminiviruses (CMGs) including African cassava mosaic virus (ACMV), East African cassava mosaic virus (EACMV) and South African cassava mosaic virus (SACMV). The Uganda, variant of EACMV (EACMV-Ug), associated with the pandemic of severe CMD in East/Central Africa, has caused devastating losses in yield thus threatening food security. In Uganda, despite the intervention of using resistant varieties to restore production, local susceptible cultivars are still being grown, especially in ‘post-pandemic’ areas. This is because resistant varieties are either not readily available or their products do not meet consumers’ taste. It is, therefore, important to assess the impact on yield of different viruses and virus combinations on local cultivars and ultimately to explore control options that can be used to minimise yield losses. A trial was conducted to investigate the effects of CMGs on growth and yield of a susceptible local cultivar, ‘Ebwanateraka’. PCR diagnostic tests were used to identify planting material infected with specific viruses/virus combinations and the viruses identified were subsequently confirmed in the planted trial. Results showed that there were significant differences on the effects of different CMGs on severity of symptoms, height of plants, biomass, storage root weight and number. Plants with dual ACMV/EACMV-Ug infections had the highest severity, shortest plants, lowest biomass and lowest yield with about 50% of the plants having no storage roots.

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