Pests and diseases

Trees in and around Woking borough can be affected by a number of tree pests and diseases. 

These include:

Our tree officers work alongside the Forestry Commission to monitor the spread of these known ‘pathogens’ and ensure all necessary steps are taken to manage them. 

It is important to note that where possible we will aim to restore trees to a healthy and safe state. If disease or pests are detected we will not automatically remove the tree.

Oak Processionary Moths (OPMs) in the borough

July 2021: The first sightings of the Oak Processionary Moth (OPM) of the year have been confirmed in the borough. Residents are being reminded to avoid all contact with this hazardous tree pest and report the locations(s) to the Forestry Commission.

Oak Processionary Moths have been present in the UK since 2012 with infestations found in London and parts of the South East, including Woking Borough, in recent years. They can be identified by their dome or teardrop-shaped nests, which range in size from a ping pong ball to as large as a rucksack. They are white when fresh, but soon become discoloured and brown.

The caterpillars have black heads and bodies covered in long white hairs, which contain proteins that can cause itchy rashes, eye, and throat irritations. They can also occasionally cause breathing difficulties in people and pets, so should not be touched under any circumstances.

The greatest risk period is May to July when the caterpillars emerge and feed before pupating into adult moths, but nests, even old ones, should not be touched at any time. The caterpillars feed on oak leaves, which can leave the trees vulnerable to other pests, diseases and drought.

What to look out for:

  • OPM moths, the adult form of the species, are undistinctive brown moths similar to other species, and are difficult to accurately identify. They are not a health hazard and do not need to be reported unlike their junior forms.
  • OPM caterpillars have a distinctive habit of moving about in late spring and early summer in nose-to-tail processions, from which they derive their name. They live and feed almost exclusively on oak trees and can sometimes be seen processing across the ground between oak trees. They have very long, white hairs which contrast markedly with the much shorter, almost undetectable irritating hairs; have a grey body and dark head. Older larvae have a central dark stripe with paler lines down each side.

How to report sightings of OPMs

To report a sighting of OPM, you will need to give a precise location as to where the infestation was sighted and, if possible, provide a photo.



Phone: 0300 067 4442

More information

Visit the Forestry Commission website for more information about tree pests and diseases