Virulence of potato cyst nematode populations used for testing potato varieties to assess resistance

As described in the new EU Commission implementing regulation (EU 2022/1192) for Globodera pallida and G. rostochiensis (PCN), testing of (new) potato varieties to assess their resistance to PCN is obligatory. The degree of resistance of potato varieties is quantified in accordance with the standard scoring notation, the relative susceptibility (RS). By including standard reference populations of PCN (Ro1: Ecosse, Ro5: Harmerz, Pa1 Scottisch and Pa3: Chavornay) and reference potato varieties it is possible to relate the new potato variety to internationally recognized levels of resistance based on the nematode multiplication rate. The results (RS) of the tested potato varieties will be listed by the EU to provide a transparent system. Additionally, local (virulent) PCN populations may be included in the resistance assays. The question arises whether the standard reference PCN populations from various EU countries are still virulent enough after many years of “cultivation” and whether these are still representative for the type of virulence present in field populations within the EU nowadays. Therefore, the aim is to compare these reference populations to each other and to local virulent field populations, which may have arisen due to the selection pressure imposed by the use of resistant potato varieties. The project is carried out in frames of EUPHRESCO network in collaboration with project partners from Belgium, Canada, Germany, Netherlands and Turkey.