Scientific Opinion on the risks to plant health posed by European versus non-European populations of the potato cyst nematodes Globodera pallida and Globodera rostochiensis
The Panel on Plant Health has delivered a scientific opinion on the different risks posed by European and non-European populations of the potato cyst nematodes (PCN) Globodera pallida and Globodera rostochiensis to solanaceous plants in the EU and on the effectiveness of current control measures. Although PCN, particularly G. rostochiensis, are widespread in the EU, crop damage is limited because breeders have been able to develop varieties that are resistant to the small number of genotypes that are present. These genotypes represent a minor subset of the gene pool and virulence that is present in South America. As new South American genotypes are very likely to have a similar potential for establishment and spread as existing European genotypes, the potato varieties currently grown in Europe will not be resistant to new virulent genotypes. As resistant varieties take a very long time to develop, the consequences of a new introduction of South American PCN would be major. The Panel therefore concluded that it is very important to maintain the current phytosanitary measures to prevent the entry of South American PCN. However, uncertainties over the effectiveness of the measures in Annex IVAI relating to place of production freedom and soil origin were noted, and the Panel identified additional risk reduction options for certain plants for planting (e.g. bulbs) and additional requirements to confirm the absence of PCN in places of production. The Panel also identified some problems with the existing control measures to reduce the spread of PCN within the EU. A thorough and well-coordinated EU-wide survey using standardized methods would be necessary to evaluate the need to maintain these measures. The monitoring of PCN populations should exploit new diagnostic techniques (e.g. mitochondrial DNA sequences) to ensure that the resistance available is deployed appropriately.