Multi-Year Evaluations of an FTA Card-Based Detection Protocol for Four Vector-Borne Viruses Affecting Potato

To reduce reliance on time consuming postharvest seed potato grow outs, a Whatman Flinders Technology Associates Plantsaver Cards (FTA)-based pathogen detection protocol based on dormant tubers was developed for four potato viruses. Viruses tested included potato virus Y (PVY), potato virus S (PVS), potato mop-top virus (PMTV), and tobacco rattle virus (TRV). Viruses were also detected from potato tubers, sprouts, and leaves using different experimental test methods and sample collection timings (harvest-FTA, storage-FTA, sprouting-FTA, sprout-enzyme-linked immunosorbent assay [ELISA], sprout-recombinase polymerase amplification [RPA], leaf-RPA, and leaf-ELISA). When compared with the leaf-ELISA, accuracy of the harvest-FTA was 92.9% (PVY) and 93.8% (PVS), and test results were available 90-days earlier than leaf-ELISA. Results from the leaf-ELISA for PMTV and leaf-FTA for TRV grossly underreport detection of these two viruses compared with results obtained using multiple tuber and sprout test methods (harvest-FTA, storage-FTA, sprouting-FTA, sprout-ELISA, and sprout-RPA). In 2020, an on-farm collaboration resulted in field implementation of the FTA card-based tuber test for detecting PVY, PMTV, and TRV from eight seed lots. Accuracy, sensitivity, and specificity for detecting PVY from these eight seed lots using the farm-FTA test method were 89, 92, and 87%, respectively, and the results were provided approximately 3 months earlier than the official results from the state seed potato certification programs. Cost analysis of the FTA card-based detection protocols showed that this approach reduced testing costs for multiple pathogens and allowed growers to use a single sampling pipeline to measure and manage multiple pathogen risks at lower costs.