If you own or manage oak trees in the area affected by oak processionary moth (OPM), you need to check which OPM management zone your trees are in. This will help you to decide what action you need to take.
Three distinct geographical zones have been defined for OPM management purposes (see map below). The official response, and any assistance available to deal with OPM, will depend on which of these zones your trees are in. They are referred to as:
- the 'Core Zone' (the central part of the West London outbreak area, coloured orange on the map);
- the 'Control' or Buffer Zone (an area surrounding the Core Zone, coloured yellow, where eradication remains the aim to prevent or minimise outward spread from the Core Zone); and
- the 'Protected Zone' (the OPM-free area, coloured green. This is effectively the whole of the remainder of the United Kingdom, where we are required to prevent incursions by OPM or, if they do occur, to take action to eradicate them).
If your trees are anywhere in the London Boroughs of:
- Hammersmith & Fulham;
- Kensington & Chelsea;
- Kingston Upon Thames;
- Richmond Upon Thames; or
- the City of Westminster,
they are in the Core Zone, where control action is not compulsory, although we strongly advise it.
If they are in the London Boroughs of:
- Wandsworth; or
- the Surrey District of Elmbridge,
they could be in the Core Zone or the Control Zone, depending on which part of the borough or district they are in. If your trees are in one of these council areas, the following maps will help you to work out which zone they are in.
In the Core Zone, it is tree owners’ responsibility to check their trees for OPM infestation and to take any necessary action. Although you will not usually be legally required to do any work, the Forestry Commission reserves the right to issue Statutory Plant Health Notices (SPHNs) requiring the removal of infestations in the Core Zone which threaten to spread into the Control Zone. This manual provides advice on the action you can take.
We strongly recommend that you do take action to protect yourself, your family, neighbours, visitors, staff, pets and livestock, and others who have reason to be close to your trees. This will also protect your oak trees from potentially damaging defoliation by the caterpillars. Severe defoliation can leave trees weakened and vulnerable to other pests, diseases and environmental stresses such as drought.
Control and Protected Zones
In the event of an interception in the Control or Protected Zone, you may be issued with a Statutory Plant Health Notice. The Forestry Commission and other plant health authorities issue these notices, requiring the owner or manager to take certain steps to eradicate the pest.
If you’re issued with an SPHN, you must follow any instructions provided within the document. If you have any questions about an SPHN you have been issued, contact the Forestry Commission.
Note that receipt of an SPHN does not mean that you’re in any trouble. Nor does it imply that you have committed an offence, or are at fault for the pest being present on your land. However, failure to comply with the requirements of an SPHN can result in enforcement action and prosecution.
The cost of eradication is the responsibility of the landowner. Owners of infested trees should retain any official documents and contact their supplier.
Outbreaks of OPM in the Control and Protected Zones are treated the same for management purposes, and we aim to eradicate them. Eradication is most likely to be achieved by a combination of methods, which include:
- surveying trees for evidence of OPM presence;
- correctly timed applications of insecticide which treat the whole of the tree canopy; and
- removal and destruction of nests.
In general terms, the Forestry Commission will take charge of treating infested trees in the Control and Protected Zones, and there will be no costs for the owner. Treatment involves spraying the trees with an approved bio-pesticide or insecticide. Spray treatment is applied between April and June as this is when the product we use is most effective.
Nest removal, which is best used as a follow-up supplement to spraying, must be at owners' expense in the Control and Protected Zones.
These distinctions between the Core and Control/Protected Zones are necessary because European Union legislation was introduced in October 2014 which recognises those parts of the UK that are outside the affected areas as a 'Protected Zone'. The Government therefore has a statutory duty to prevent infestation of the Protected Zone, and this has to be the focus of government policy and government-funded activity.
Accordingly we focus government-funded control effort on the buffer area (the 'Control Zone') and the Protected Zone. The Zones have been defined using the best evidence and scientific advice available to us, and we need to focus public resources on controlling those populations which most threaten to expand into, or further into, the Protected Zone.
If you do any other work on trees in either zone, especially if it involves cutting branches (tree surgery), there are other considerations which must be taken into account. See section 10 - Other work on oak trees.
The remainder of this manual provides information to help you to help us, the Forestry Commission and the other partners involved, such as local authorities, to prevent or minimise further spread of the pest and to keep its impacts to a minimum.