In many developing countries, yields of root and tuber crops are significantly reduced due to diseases and pests in the planting material. In sweetpotato, the sources of planting material, which are either vine cuttings or roots,  are equivalent to clonal seed for vegetative propagation.The development and transfer of new methods and technologies for producing disease-free clonal seed can overcome this constraint and help unlock the significant yield potential of these crops. For potato, the use of virus detection and tissue culture techniques in tuber seed programs is common especially in developed countries. Such techniques have not been used for sweetpotato, even in the United States where propagation material is periodically re-newed to maintain clonal purity. Virus elimination is not an objective or consequence of these programs.