N	Risk mitigation measure	Effect on the pest	Evaluation and uncertainties
1	Registration of production sites	Yes	The registration and the release of the UK plant passport should be enough to warrant pest‐free plant material for a protected zone quarantine pest in the UK. Uncertainties – Level of awareness of the nursery staff regarding the possibility of birch being a host of T. processionea
2	Physical separation	No	Not relevant, as the production is not carried out in separate areas, the possibility that the pest can move from the outside to the nurseries and from one tree species to another within the nurseries is concrete.
3	Certified plant material	Yes	The use of certified material should be enough to warrant pest‐free status. Uncertainties – None
4	Growing media	No	Not relevant. The pest is not affected by the growing medium as in the nurseries all the stages develop above ground.
5	Surveillance, monitoring and sampling	Yes	Regular surveys are carried out during the production by visual inspection of the plants. Any report of a quarantine pest is provided. Uncertainties – Level of awareness of the nursery staff regarding the possibility of birch being a host of T. processionea
6	Hygiene measures	No	Weeding and disinfection are not relevant for this pest.
7	Removal of infested plant material	Yes	The removal of infested plants at the larval stage will have a positive effect. Egg masses are not expected on Betula. Uncertainties – None
8	Irrigation water	No	Water is not relevant for this pest.
9	Application of pest control measures	Yes	The pest is easy to control at the larval stage and being a quarantine pest, its presence must be reported and measures taken. However, with the exception of egg parasitoids and other generalist enemies feeding on eggs, the egg masses are not susceptible to any crop protection method. No treatments available against the moths. Uncertainties – Whether biological control using B. thuringensis against larvae or other biocontrol agents against eggs are used – Whether appropriate chemical insecticides are used
10	Measures against soil pests	No	Soil is not relevant for this pest.
11	Inspections and management of plants before export	Yes	Inspections carried out before export will be visual and would be enough to warrant that commodities are free of larvae. Uncertainties – Level of awareness of the nursery staff regarding the possibility of birch being a host of T. processionea
12	Separation during transport to the destination	Yes	The separation of the plants during the transport would reduce the possibility that larvae are moving among plants if the transport happens when green leaves are occurring between April and August. Uncertainties – The period when the plants are moved – The presence of green leaves at the time of transport