Assessing the sweetpotato virus disease and its associated vectors in northwestern Tanzania and central Uganda.

Abstract

A study was conducted in sweet potato farmers’ fields in Tanzania and Uganda to determine the status of sweet potato virus disease (SPVD) incidence and its vectors. SPVD incidence was high (66 to 100%) in Tanzania but low (10 - 40%) in Uganda. SPVD symptom expression and severity were highly variable both within and between countries. Whitefly (Bemisia tabaci) but not aphids were observed in all the fields and their abundance varied remarkably between locations. In Tanzania, sweetpotato chlorotic stunt virus (SPCSV) was serologically detected in 50% of the samples and sweetpotato feathery mottle (SPFMV) in 45% often in dual infection. Sweetpotato mild mottle virus (SPMMV), sweetpotato mild speckling virus (SPMSV), sweetpotato chlorotic fleck virus (SPCFV) and sweetpotato virus G (SPVG) occurred in low frequency. However, SPCSV was detected in (100%) of the samples collected from Uganda followed by SPFMV (67%). The nature of SPVD incidence, symptom severity, whitefly, and aphid abundance observed in this study suggest the complex nature of SPVD in East Africa. Immediate prospects for controlling SPVD will depend on an enhanced understanding of disease variables and their ecological relationships. Key words: Sweetpotato, incidence, severity, whitefly, aphids.