Defra answers questions on UK oak processionary moth explosion

Some of the 60 cases of oak processionary moth came from oaks imported from Europe without paperwork or notification to authorities, Defra has said.

OPM has exploded around the UK this summer, with caterpillars found in 60 locations in the Protected Zone outside of London and neighbouring areas. UK growers are concerned that reckless or ignorant importing of infected oaks could damage the UK industry, which has been encouraged to grow more of the trees itself.

On 12 July Defra introduced further restrictions on oak imports. These measures mean only imports of certain oak trees are allowed, including those from OPM free countries and areas, and oaks that have been grown under complete physical protection for their lifetime. This Statutory Instrument (SI) applies to all oak trees, except cork oak, over a certain size.

Defra responded to several questions from Horticulture Week about the recent spread of OPM.

Were the oaks found with OPM this month around the UK imported directly by landscapers?

The plant health service is dealing with findings of oak processionary moth caterpillars on imported trees. 60 planting sites are affected in the UK. These trees were imported by a number of different types of businesses. We are continuing to investigate the situation through tracing work and surveillance activities.

Did they come from nurseries in a Protected Zone?

The infested trees were supplied from within the EU, from areas that are not designated as Protected Zones. Most of the affected consignments were from the Netherlands.

The plant health service has received reports of an exceptional expansion of the OPM population in parts of Europe, due to the weather conditions experienced last year. This is likely to have contributed to the pest pressure around supplying nurseries.

We are continuing to investigate the wider situation through tracing work and surveillance activities, and will take swift and appropriate action.

Were they inspected by that nation's Plant Inspector with proper paperwork? 

With very limited exceptions, the oak trees were accompanied by plant passports to confirm that required official inspections had been undertaken in the country of export.

The recent interceptions have highlighted that the import requirements were not providing an adequate degree of assurance about pest freedom, which meant that we had to review aspects of the national measures introduced in 2018. In particular it is clear that the requirements for nurseries in the open air in infested areas, including to confirm vicinity freedom, are not working and so we have taken action to revoke that option.

Defra has introduced strengthened national legislation to protect oak trees against OPM through movement and import. The legislation prohibits the movement of certain oak trees into the OPM Protected Zone unless specific conditions are met.

With Defra requesting over the past two years that UK nurseries invest heavily in oak production, they are now fearful that Defra will ban the movement of their UK production, just as Defra did with ash. Is this a possibility?

This is not currently being considered and the focus has been on strengthening protection against high risk oak tree movements (i.e. larger trees from areas where the pest is present) .

However we keep the situation under continuous review and have not ruled out any further measure that would help us to ensure the strictest biosecurity to protect our trees.

How can Defra be certain that many more landscapers, garden designers, estate managers, etc. have not imported oaks from Holland which APHA have no trace of, and how do they propose to stop them continuing to import oaks, highly likely with more OPM?

A statutory Instrument on oak was introduced in 2013, this means that all imported oak trees should be declared to the Plant Health Service.

Defra has introduced strengthened national legislation to protect oak trees against OPM through movement and import. The legislation prohibits the movement of certain oak trees into the OPM Protected Zone unless specific conditions are met.

If a nest is discovered and you are in the Protected Zone or the Buffer Zone, it must be reported via TreeAlert, and if you trade in oaks you must contact you local APHA Plant Health Inspector to report the finding. The Government will take action and the infestation will be sprayed and the nest eradicated and possibly the trees destroyed. There is no compensation for loss of trees, but Defra will fund the OPM eradication which is led by the Forestry Commission.

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