Pest survey card on Cryphonectria parasitica

This pest survey card was prepared in the context of the EFSA mandate on plant pest surveillance (M-2020-0114), at the request of the European Commission. Its purpose is to guide the EU Member States (MSs) in preparing data and information for surveys for the causal agent of chestnut blight, Cryphonectria parasitica. Cryphonectria parasitica is a protected zone quarantine pest. Therefore, the objective of this pest survey card is to provide the relevant information needed for the EU Member States that have protected zone status for this pest to prepare surveys. Cryphonectriaparasitica is a well-defined and distinguishable fungal species of the family Cryphonectriaceae. The pathogen is listed as a protected zone quarantine pest in Czechia, Sweden, Ireland and Northern Ireland, and as a Union regulated non-quarantine pest (RNQP). Cryphonectria parasitica is native to eastern Asia and is widely present in North America and in many countries of Europe that have significant European chestnut (Castanea sativa) populations. The main hosts of the pathogen are Castanea spp. but several Quercus species and other tree species can be infected. Cryphonectria parasitica is a bark-inhabiting pathogen which only infects the above-ground parts of trees and produces cankers, causing diebacks and leading to the death of the upper parts of susceptible trees. The fungus spreads naturally via conidia and ascospores. Rain disperses conidia over short distances, while the wind disperses ascospores over longer distances. Human activities, such as the trade of infected host plants, wood and bark, also facilitate the pathogen's spread over longer distances. Climatic and ecological conditions are not to be considered as a limiting factor for the establishment and spread of C. parasitica in the EU Member States where the pest is not already present. The occurrence in Europe of the dsRNA hypovirus CHV-1, which acts as biological control agent, could dramatically reduce its virulence. Hypovirulent strains do not produce ascospores and do not lead to the death of Castanea spp. Cryphonectria parasitica can be detected by visual examination of symptomatic plants (cankers, dieback, epicormic shoots and characteristic fruiting structures) and morphology but needs to be confirmed by molecular analysis.