Seed potatoes: multiplex real-time RT-PCR replaces the eye-plug test and ELISA from 1 February 2027
A regulation of Poland’s Minister of Agriculture of 29 July 2026 (Journal of Laws 2026 item 1041) changes the verification assessment of seed potatoes: instead of the eye-plug test on plants grown from cut eyes and the DAS-ELISA immunoassay, the laboratory tests material taken directly from the tubers with a multiplex real-time RT-PCR molecular test. The change applies from 1 February 2027.
- The test covers viruses that can cause significant yield losses, including potato leafroll virus (PLRV) and potato viruses A, M, S, X and Y (PVA, PVM, PVS, PVX, PVY); it is run on tuber samples from seed crops that passed field inspection and on all appeal and control samples.
- A small piece of tissue is cut from the stolon end of each of the n × 240 tubers; the pieces are randomly grouped into n × 15 primary sub-samples of 16 pieces, and the lysates of three primary sub-samples are pooled into secondary sub-samples. If a virus is found in a secondary sub-sample, the primary sub-samples are tested for all viruses covered.
- Tissue pieces are stored below –20 °C and the lysate at about 4 °C for up to 7 days (longer below –20 °C); the infection level is estimated with the SeedCalc8 program of the International Seed Testing Association (ISTA), and total infection is the sum of the results for the individual viruses.
- The composite sample from a crop of up to 10 ha consists of 240 tubers from 24 partial samples of 10 tubers; tubers are taken between the 10th and 20th day after haulm destruction, and for early varieties not before 10 July, medium-early ones 1 August and late ones 20 August. If the sample delivered is in a state that prevents taking material for testing, a new sample is taken.