Reaction of Sweetpotato Landraces to Sweetpotato Virus Disease in Uganda

Sweetpotato is an important root crop in Uganda after cassava. It is mainly grown as a food staple and source of cash income by the majority of the rural communities. However, sweetpotato production is constrained by a number of factors especially sweetpotato virus disease. Sweetpotato virus disease caused by dual infection of sweetpotato feathery mottle virus (SPFMV) and sweetpotato chlorotic stunt virus (SPCSV) occurs throughout the major sweetpotato growing areas of Uganda. Ten sweetpotato landraces collected from areas of low (4) and high (6) sweetpotato virus disease (SPVD) incidences were evaluated for resistance to SPVD for three seasons at Namulonge in central Uganda. In general, the landraces from low incidence areas recorded the highest incidences of SPVD compared to those from the high SPVD infection areas. The highest SPVD incidences of 91.5 and 46% were recorded at harvest on Araka and Ombivu, respectively. Similarly, genotypes with higher incidences recorded the highest AUDPC. These results suggest that sweetpotato landraces from low SPVD incidence areas are not necessarily resistant but should be evaluated at disease “hotspots” areas to confirm their resistance and yield potential.