Seed health trade-offs in adopting quality declared seed in potato farming systems

The availability of quality seed to smallholder farmers for most crops in sub-Saharan Africa is a problem due to low production and availability of certified seed. Ethiopia has adopted quality declared seed (QDS) certification protocols for arable crops including potato. However, the procedure sets that only 10% of seed fields submitted to certification as QDS are inspected by external inspection. Consequently, a survey was conducted in Amhara, Oromia, and Southern Nations Nationalities and Peoples' (SNNP) regions in Ethiopia to determine the reliability of quality control in potato QDS done through only visual assessment by determining the incidence of latent Ralstonia solanacerum (Rs) infection among farmer seed group cooperatives (FSGCs) and individual decentralized seed multipliers (IDSM). Tuber samples were collected from 446 potato fields in selected districts for both seed and ware potato producers. Data revealed that all the varieties collected in the study were equally prone to latent Rs infection. The proportion of latent Rs infected fields was highest in SNNP (39.6%) and least in Amhara (10.8%) region. Latent Rs infection was as high in samples collected from fields of FSGCs as in home-saved or local seed (20.5%) and lowest among IDSM (8.7%). These data reveal that certifying potato QDS visually as the current practice in Ethiopia is inadequate for seed health assurance and a recipe for disseminating Rs. To contain further spread of the disease, therefore, all seed classes including QDS in Ethiopia should be tested for latent Rs infection if they are to be formally distributed.