Scientific Opinion on the pest categorisation ofCryphonectria parasitica(Murrill) Barr

Abstract

The European Commission requested the EFSA Panel on Plant Health to perform a pest categorisation of Cryphonectria parasitica (Murrill) Barr, the fungal pathogen responsible for chestnut blight, a highly destructive disease that kills trees through bark cankers. The pathogen is listed in Annex IIAII of Directive 2000/29/EC. Its identity is clearly defined as C. parasitica (Murrill) Barr and methods exist for its discriminative detection. Several hosts are known, but the main hosts are species of Castanea and Quercus, particularly C. sativa and Q. petraea. These two host species are present in all the EU Member States and the disease has been recorded in most parts of the risk assessment area. C. parasitica is absent in Denmark, Estonia, Finland, Ireland, Malta, Iceland and Norway. No information is available on the presence of the pathogen in Latvia, Lithuania or Luxembourg. In the Czech Republic and Poland, C. parasitica has been eradicated. There are no recognised ecological or climatic factors limiting the potential establishment of the pathogen in the EU Member States where the pathogen is not known to occur. The pathogen can spread by propagules (mainly conidia, but also ascospores and mycelium) that are dispersed by wind, rain or vectors, as well as via the movement of infected or contaminated host plants for planting and bark, particularly asymptomatic ones. Control methods used against C. parasitica include exclusion and eradication, chemical control, host genetic resistance and biological control (hypovirulence). The most successful control methods of C. parasitica in the EU are exclusion and eradication, and hypovirulence. Potential consequences of the damage caused by C. parasitica include yield losses of fruit and wood, reduction in biodiversity and habitat loss for associated organisms.

Commodity risk assessment of Quercus robur plants from the UK

“…Cryphonectria parasitica symptoms can be confused with other cankers in the first stages, but the presence of mycelial fans and appearance of the fruiting bodies makes the identification clear. Isolated on potato dextrose agar can identify also hypovirus-infected fungi, and molecular methods have been developed for identification (EFSA PLH Panel, 2014). Some confusion can occur with cancers caused by Gnomonopsis castaneae (Lione et al, 2019) The reports for Fagus sylvatica are only taken from artificial inoculation (Dennert et al, 2020).…”

Commodity risk assessment of Quercus petraea plants from the UK

“…Cryphonectria parasitica symptoms can be confused with other cankers in the first stages, but the presence of mycelial fans and appearance of the fruiting bodies makes the identification clear. Isolated on potato dextrose agar can identify also Hypovirus-infected fungi, and molecular methods have been developed for identification (EFSA PLH Panel, 2014).…”