This rapid assessment shows:

Risk of entry - Although the 15 interceptions since 2001 suggests a moderate likelihood of entry, the last finding was in 2007 and transfer to living elm trees via the bonsai pathway (dwarfed Ulmus and Zelkovia plants directly from China or indirectly via the Netherlands) is unlikely. 

Risk of establishment - Establishment is likely both outdoors and in protected cultivation. An outbreak occurred in Dutch glasshouses on Ulmus and Zelkova bonsai in 2000 but was successfully eradicated. 

Economic impact - It is likely to have a small to medium impact in the UK, the main risk being the loss of quality in bonsais. The fungus produces spores that permit airborne dispersal so spread could occur at a moderate pace. 

Endangered area - Ulmus is very widespread in the UK and all populations are at risk. 

Risk management - As S. ulmea can survive in leaves, petioles, stems and fruits only destruction of infected hosts would be effective in eradicating the pathogen. It is listed in Annex IIAI on Plants of Ulmus L. and Zelkova L., intended for planting, other than seeds but there are no Annex IV requirements. To strengthen the regulations it would seem appropriate to add specific requirements to Annex IVAI for plants for planting of Ulmus and Zelkova requiring that they have originated in an area free from S. ulmea.