Erwinia amylovora, the causal agent of fire blight disease, is regulated as a protected zone quarantine pest in Finland. To prevent the introduction of E. amylovora, all its host plants traded to Finland from other EU countries must have an official plant passport. Currently, plants from the genus Sorbus are considered hosts of E. amylovora under the existing regulation. However, recent reclassification of Sorbus has resulted in the establishment of new genera, including Scandosorbus and Hedlundia. This has led to uncertainty about whether these newly established genera should be regulated as hosts of E. amylovora. Consequently, the Risk Assessment Unit of the Finnish Food Authority was asked to assess the host status of Scandosorbus and Hedlundia species for E. amylovora.

We based our assessent on a comprehensive literature review of species-specific information on naturally occurring infections of E. amylovora in the genus Sorbus s.l., as well as experimental studies that have tested susceptibility under field or greenhouse conditions.

The literature review revealed no evidence of natural infections by E. amylovora in any species belonging to the genera Hedlundia and Scandosorbus. While some experimental studies have demonstrated mild disease development in certain species belonging to these genera, the lack of further supporting evidence suggests that these species should not be considered as hosts of E. amylovora. However, our assessment was based on very limited available information, making the conclusions uncertain. For most species belonging to Hedlundia, there is no information available on their susceptibility. Given that resistance to fire blight can vary even among closely related taxa, it is possible that some species or cultivars belonging to Hedlundia, for which data is currently lacking, may be susceptible to E. amylovora. Further studies are needed to verify the host status of these species.

Interestingly, we found evidence of natural infections of E. amylovora in Sorbus s.l. species that are now classified under the newly established genera Aria, Alniaria, Cormus, and Torminalis. The host status of these genera may need revision, as they potentially should be considered hosts in the Commission regulation regarding the trade of E. amylovora host plants.