An integrated seed health strategy and phytosanitary risk assessment: Potato in the Republic of Georgia

Context: Potato is an essential food staple and a critical crop for rural livelihoods in the Republic of Georgia, where many phytosanitary risks threaten production. Objective: The objectives of this study were, first, to characterize the current seed and ware potato transaction network, value chain, varietal adoption, and phytosanitary risks for Georgia. Second, we modeled scenarios for the spread of an emerging pathogen, Synchytrium endobioticum, in Georgia as part of a geographic risk assessment analysis. Third, we coupled risk estimated in our simulation experiments with risk of reintroduction or invasion of pathogens via international trade or habitat connectivity. We found that a majority of seed potato is obtained from local sources in Georgia, and is of unknown phytosanitary quality. Methods: An expert elicitation workshop was held to characterize the potato value chain as well as potato production more generally in the Republic of Georgia. To characterize future risk of pathogen spread through Georgia we leveraged epidemic network analysis, an analysis of potato cropland connectivity, and an evaluation of international potato trade in a multi-step risk assessment. Results and Conclusions: Five varieties, including the variety Jelly, made up 65% of planted area throughout the country. Several pathogens and pests were listed as contributing to annual yield loss with S. endobioticum, causing potato wart, identified as the greatest emerging risk to the country. Through simulation analyses of potential spread scenarios within country, we identified municipalities in Adjara and Samtskhe-Javakheti to be at particularly high risk for introduction of potato wart and we recommend enhanced surveillance in these regions. Our analysis of cropland connectivity revealed that the region where Georgia, Azerbaijan, and Armenia meet are at a high risk for local spread of seedborne pathogens such as S. endobioticum. We propose these locations as targets for enhanced surveillance and mitigation strategies.