Scientific Opinion on the risk to plant health posed by Chrysanthemum stunt viroid for the EU territory, with identification and evaluation of risk reduction options

Viroids of the Mediterranean Basin

There has been substantial progress in the Mediterranean countries regarding research on viroids. Twenty-nine viroid species, all belonging to Pospiviroidae and Avsunviroidae genera, have been detected in the Mediterranean Basin. Not only have detection methods, such as reverse transcription-quantitative polymerase chain reaction and next-generation sequencing, been used for viroid detection, along with molecular hybridization techniques allowing for rapid detection, identification, and characterization of known and novel viroids in these countries, but eradication measures have also been taken that allowed for the efficient elimination of certain viroids in a number of Mediterranean countries. The eradication measures were followed as recommended by the European and Mediterranean Plant Protection Organization, which is known by its abbreviation, EPPO. The Mediterranean Region has been a niche for viroids since ancient times due to the warm climate and the socio-cultural conditions that facilitate viroid transmission among different host plant species.

List of non-EU viruses and viroids infecting potato (Solanum tuberosum) and other tuber-forming Solanum species

The European Commission requested a pest categorisation of the non-EU viruses and viroids of potato (hereafter referred to as viruses). As a first step, a systematic literature and database search was carried out to identify the viruses reported to naturally infect Solanum tuberosum and other tuber-forming Solanum spp (hereafter referred to as potato). Based on the global distribution and on the prevalence inside the European Union (EU), the Panel identified 40 non-EU viruses known to occur only outside the EU or with only a limited presence in the EU (reported in only one or few Member States (MSs) and/or with restricted distribution, outbreaks). Twenty-seven viruses were identified as having a significant presence in the EU (known to occur in several MSs, frequently reported in the EU, widespread in several MSs) or reported only from the EU so far, and will be excluded from further categorisation in the frame of the present mandate. Five viruses remained with an undetermined standing because the available information did not allow their allocation to one of the above groups. The viruses considered non-EU and those with undetermined standing will be further categorised if not addressed by EFSA in previous scientific opinions. Seven viruses for which non-European isolates are specifically regulated in Annex I of directive 2000/29/EC will be categorised separately. The main knowledge gaps and uncertainties of this grouping concern the natural host status of potato, the taxonomy, and/or information on the geographical distribution and prevalence of some of the analysed viruses.