The 2007 EU PCN Directive requires Member States of the EU to submit annually a list of all new potato varieties which have found to be resistant to PCN by official testing. Until 2010, all cultivars of potato entered for the UK National List VCU (Value for Cultivation and Use) trials have been tested for resistance to the dominant pathotypes of PCN occurring in the UK. Under the new Directive all official testing for resistance will be harmonised, including assessing resistance by a common scoring system based on a 1 to 9 scale.
In the UK, testing for resistance to Globodera pallida (pathotypes Pal & Pa2/3) is conducted at two centres: Edinburgh (SASA) and Cambridge (NIAB). Testing for resistance to Globodera rostochiensis (pathotype Rol) is conducted at Edinburgh only.