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 have confirmed three cases in Glamorgan and Flintshire. Scottish Government have confirmed three cases in Fife, Inverness and Lanarkshire.
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.
Chief plant health officer Professor Nicola Spence has written a column in the Daily Telegraph calling for public vigilance: "Yet strong biosecurity relies on everyone playing their part, which is why I am calling for the public to check their trees and report any signs of OPM.
"It is vital we all play our part to protect this important natural asset – the majestic oak. Remember: Spot it. Avoid it. Report it."
The HTA said: "All current findings have originated from infested areas in other countries. Although there is no suggestions that UK nurseries within the Protected Zone have grown or supplied such trees, the HTA advises all growers and nurseries stocking oak trees embark as soon as possible on a precautionary spraying schedule, regardless of your sources of stock or location.
"The HTA reiterates to landscapers, gardeners and developers it is essential to conduct further inspections on all oaks planted in the last 12 months."
This Statutory Instrument (SI) applies to all oak trees, except cork oak, over a certain size. This is because these trees represent the greatest likelihood of introducing OPM into the UK PZ, as they are more susceptible to pest populations and more difficult to inspect.
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.
Protected zones are: Ireland, United Kingdom (excluding the local authority areas of Barking and Dagenham; Barnet; Basildon; Basingstoke and Dene; Bexley; Bracknell Forest; Brent; Brentwood; Bromley; Broxbourne; Camden; Castle Point; Chelmsford; Chiltem; City of London; City of Westminster; Crawley; Croydon; Dacorum; Dartford; Ealing; East Hertfordshire; Elmbridge District; Enfield; Epping Forest; Epsom and 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 and 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 and Malling; Tower Hamlets; Uttlesford Waltham Forest; Wandsworth; Watford; Waverley; Welwyn Hatfield; West Berkshire; Windsor and Maidenhead; Woking, Wokingham and Wycombe) until 30 April 2020.