How is Defra tackling the threat to UK biosecurity posed by oak processionary moth-infested imports?

Oak processionary moth (OPM) has exploded around the UK this summer, with caterpillars found in more than 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.

Defra says not all the OPM-infested oak imports had been inspected and it has subsequently toughened up regulations. "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," it adds.

"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, so we have taken action to revoke that option."

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 applies to all oak trees, except cork oak, over a certain size.

Defra says: "These trees were imported by a number of different types of businesses. 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."

UK growers' investment and efforts at becoming more self-sufficient are not now a focus as the Government seeks to deal with the OPM outbreaks. Some 1.1 million oaks were imported in 2013-16, with 1,144 Animal & Plant Health Agency (APHA) notifications and 155,799 oaks imported from June to December 2016. Growers fear an oak movement ban, which would wreck trade as a ban did with ash in 2012 after the ash dieback crisis.

Defra says: "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."

Import campaigning

Growers such as Majestic Trees' Steve McCurdy have long campaigned against direct import, online or straight to landscaping sites. So how can Defra be certain that many more landscapers, garden designers and estate managers have not imported oaks from Holland of which APHA has no trace?

Defra says a statutory instrument on oak was introduced in 2013, which means that all imported oak trees should be declared to the plant health service.

The background to this year's spike in findings is that OPM has been a growing threat for more than 15 years. The pest arrived in Britain in 2005 via Dutch trees imported for a landscaping project in Kew, London, and responsibility initially fell between health and environment departments in Government. Biosecurity minister Lord Gardiner says: "We should have dealt with it immediately then. I regret it wasn't dealt with with the vigour we should have."

The pest spread in and around London, which is now an infested zone where eradication is not being attempted. There is a buffer control zone around this and, since 2014, a protected zone for the rest of the UK, which restricts the import and movement of oak.

Perthshire-based Glendoick Gardens managing director Ken Cox says new controls on oak imports "may be too little too late if the number of outbreaks is anything to go on". He notes that it has taken the Government three years to introduce proper measures following a finding of OPM at the RHS Chelsea Flower Show, on a direct import, in 2016. The pest was first found near Kew in London in 2006 and has since spread around the capital and parts of the Home Counties. In February 2019, the RHS banned oak from Chelsea.

Defra defends its record: "We have had a series of measures in place since January 2013, when a statutory notification for oak was first introduced. In 2018, we introduced measures to restrict the import of oak trees. [In July 2019] we introduced even tighter controls on oak imports. The latest legislation means imports of larger oak trees are only allowed from OPM-free countries, from designated pest-free areas including protected zones — an area of the EU declared free of OPM — and those that have been grown under complete physical protection for their full lifetime."

A public education programme about the dangers of the irritant hairs on the caterpillars could be the way forward, says The Royal Parks chief executive Andrew Scattergood. More education for oak importers who do not know the rules would be helpful too, say UK growers.

Defra says: "Protecting our country from pests and diseases is vital to safeguard our environment, economy and health. From 2012 to 2019, we will have invested more than £37m into tree health research."

TreeAlert: reporting OPM nests

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 your local APHA plant health inspector to report the finding. The Government will take action — the infestation will be sprayed, the nest will be eradicated and the trees will possibly be destroyed. There is no compensation for loss of trees but Defra will fund OPM eradication, which is led by the Forestry Commission.

A typical recent OPM report states: "Oak processionary moth (Thaumetopoea processionea) has been found on eight consignments of Quercus robur, Quercus petraea, Quercus palustris and Quercus cerris from the Netherlands. The APHA intercepted the plants at unspecified "inland locations" on 29, 30 and 31 July and 1 and 2 August. In all cases, they were destroyed."

Affected counties in England include Cambridgeshire, County Durham, Devon, Dorset, Essex, Gloucestershire, Greater Manchester, Hampshire, Hertfordshire, Kent, Lancashire, Leicestershire, Lincolnshire, London, Merseyside, Middlesex, Nottinghamshire, Oxfordshire, Southampton, Staffordshire, Suffolk, Surrey, Warwickshire, West Midlands, Wiltshire and Yorkshire.

The Welsh Government has confirmed three cases — two in Glamorgan and one Flintshire. The Scottish Government has confirmed three cases — in Fife, Inverness and Lanarkshire.

Protected zones: Ireland, UK (excluding the local authority areas of Barking & Dagenham, Barnet, Basildon, Basingstoke & Dene, Bexley, Bracknell Forest, Brent, Brentwood, Bromley, Broxbourne, Camden, Castle Point, Chelmsford, Chiltern District, City of London, City of Westminster, Crawley, Croydon, Dacorum, Dartford, Ealing, East Hertfordshire, Elmbridge District, Enfield, Epping Forest, Epsom & Ewell District, Gravesham, Greenwich, Guildford, Hackney, Hammersmith & Fulham, Haringey, Harlow, Harrow, Hart, Havering, Hertsmere, Hillingdon, Horsham, Hounslow, Islington, Kensington & Chelsea, Kingston upon Thames, Lambeth, Lewisham, Medway, Merton, Mid Sussex, Mole Valley, Newham, North Hertfordshire, Reading, Redbridge, Reigate & Banstead, Richmond upon Thames, Runnymede District, Rushmoor, Sevenoaks, Slough, South Bedfordshire, South Bucks, South Oxfordshire, Southwark, Spelthorne District, St Albans, Sutton, Surrey Heath, Tandridge, Three Rivers, Thurrock, Tonbridge & Malling, Tower Hamlets, Uttlesford, Waltham Forest, Wandsworth, Watford, Waverley, Welwyn Hatfield, West Berkshire, Windsor & Maidenhead, Woking, Wokingham and Wycombe) until 30 April 2020.

Have you registered with us yet?

Register now to enjoy more articles and free email bulletins

Sign up now
Already registered?
Sign in

Read These Next



These evergreen architectural plants provide feathery foliage and seasonal colour, writes Miranda Kimberley.

OPEN FOR ENTRIES: Horticulture Week Business Awards 2020

OPEN FOR ENTRIES: Horticulture Week Business Awards 2020



These unfussy plants offer a welcome splash of colour in the garden or as a houseplant, writes Miranda Kimberley.

Follow us on:
  • Facebook
  • LinkedIn
  • Twitter
  • Google +


The Horticulture Week Business Awards is now open for entries

Horticulture Jobs
More Horticulture Jobs

Horticulture Week Top 70 Ornamentals nurseries

See our exclusive RANKING of ornamentals nurseries by annual turnover plus the FULL REPORT AND ANALYSIS

Tim Edwards

Boningales Nursery chairman Tim Edwards on the business of ornamentals production

Read Tim Edwards

Pest & Disease Tracker bulletin 

The latest pest and disease alerts, how to treat them, plus EAMU updates, sent direct to your inbox.

Sign up here

Are you a landscape supplier?

Horticulture Week Landscape Project Leads

If so, you should be receiving our new service for Horticulture Week subscribers delivering landscape project leads from live, approved, planning applications across the UK.

Peter Seabrook

Inspiration and insight from travels around the horticultural world

Read more Peter Seabrook articles