Prevent the introduction and spread of tree pests and diseases

Find out what you can do to prevent tree pests and diseases from getting established, or to prevent or slow their spread and the damage they do.

Biosecurity refers to a set of precautions that aim to prevent the introduction and spread of harmful organisms. These include non-native tree pests, such as insects, and disease-causing organisms, called pathogens, such as some bacteria and fungi.

Tree pests and diseases can be transported between or within countries via a number of pathways, including:

There has been a significant increase in the number of non-native tree pests and diseases being introduced to the United Kingdom since the early 2000s. This demonstrates the need for us all to take action to provide our trees, woods and forests with greater protection. By implementing appropriate biosecurity measures, we can significantly reduce the risk of introducing and spreading tree pests and diseases.

This page will show you how to maximise good tree health through biosecurity.

See Forestry Commission guidance on importing and exporting wood and timber products.

What you can do


Tree pests and diseases can have a significant impact on our landscape, but there are some simple steps members of the public can take to help limit their spread:

  • drive and park your vehicle only on hard-standing surfaces such as tarmac where possible when visiting outdoor areas such as woodlands, parks or gardens
  • clean mud, organic material and water off your boots, bikes and buggies – and the dog – before you leave, because fungi, bacteria and insects can live in these materials
  • Don’t risk it!’ – please don’t bring any plant or tree products back from trips abroad, because these might be carrying harmful non-native tree pests or pathogens
  • report any trees that you suspect are in ill-health to the Forestry Commission using Tree Alert

Industry professionals

People working in the arboriculture, forestry and landscaping industries are considered a particularly high-risk group for their potential to spread tree pests and diseases.

The Forestry Commission has therefore worked closely with the following organisations to develop industry-specific biosecurity guidance in an effort to reduce their members’ risk of introducing or spreading pests and diseases:

By following the three calls to action from our industry guidance (‘Think kit, think transport, think trees’) alongside the public biosecurity guidance above, industry professionals can significantly reduce the risk:

‘Think kit’:

  • make sure all equipment, including boots, clothing, ropes and saws, is free from soil and organic material before entering and leaving a site
  • regularly clean ropes as per the manufacturer’s guidance, or use dedicated ropes for particular sites
  • clean and disinfect chainsaws (pruning saws and other cutting tools as part of regular routine maintenance, and before moving to new sites)

‘Think transport’:

  • remove any build-up of soil and organic material on vehicles and machinery, including cabs, wheels and foot wells, before leaving each site
  • use proper off-site wash-down facilities regularly

‘Think trees, plants, and materials’:

  • develop relationships with nurseries you can trust so they can help you responsibly source plant and tree stock from pest- and disease-free areas
  • keep accurate, up-to-date records of all purchases and supplies to assist with tracing exercises in the event of an outbreak
  • regularly monitor plant and tree stock for signs of ill-health, and report any suspect symptoms to us using Tree Alert
  • if you’re responsible for importing or moving plants, check your plant passport and registration requirements with APHA before doing so
  • source landscaping materials only from pest- and disease-free areas
  • be aware of any restrictions in place, or phytosanitary (plant health) measures and treatments required when importing certain materials or their packaging
  • consider specifying British-grown plants to avoid being party to an accidental introduction of a pest or disease

When working on a site that is subject to a Statutory Plant Health Notice (see below), or where a pest or disease has been confirmed, you must follow any additional biosecurity guidance for that pest or disease in addition to the measures above.

If you must remove infected or infested material from such sites for safety reasons, you must ensure that:

Land owners and managers

As a land owner or manager, it’s particularly important that you implement appropriate biosecurity measures to prevent the introduction and spread of tree pests and diseases. Not only can these organisms affect the economic value of your trees, they can also have a wider negative impact on other species and habitats.

By following the biosecurity guidance provided above for the public and industry professionals, you can significantly reduce the risk of tree pests and diseases spreading on to your land. If, however, a tree pest or disease is confirmed on the land you own or manage, there are some additional measures you need to follow:

Statutory Plant Health Notices (SPHNs)

If the tree pest or disease found on the land you own or manage is classified as notifiable, you may be issued with an SPHN. The Forestry Commission and other plant health authorities issue these notices requiring the owner or manager to take certain steps to eradicate or contain notifiable pests and diseases.

SPHNs requiring eradication may require measures to kill the infected or infested trees, such as by felling or ring barking. SPHNs ordering containment measures may allow the infected or infested trees to remain standing, but require any susceptible material to remain on site.

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 doesn’t mean that you’re in any trouble. Nor does it imply that you have committed an offence, or are at fault for the pest or disease being present on your land. However, failure to comply with the requirements of an SPHN can result in enforcement action and prosecution.

Non-notifiable pests and diseases

You’re not required to take any action if the tree pest or disease found on your land is not notifiable. We do, however, recommend that you take the following measures to ensure people’s and animals’ safety, and to minimise any further spread of the pest or disease. You should:

  • continue to implement the biosecurity measures in the public and industry professionals sections above
  • make any visitors aware of the presence of pests and diseases on your land through information boards, posters at entry points, and/or by adding information and biosecurity guidance to your site’s website, if available
  • monitor the trees’ safety as the infection or infestation progresses, and prune or fell affected trees if they threaten to cause damage or injury
  • in low-density situations, such as in parks or gardens, slow the spread of pests and diseases by removing and disposing of (by burying, composting or, where permitted, burning) infected trees and their fallen leaves and branches

Biosecurity kit

Putting together a simple, portable biosecurity kit can help you implement simple measures every day to help limit the introduction and spread of tree pests and diseases. The following are cheap and easily obtained items to include in your kit:

  • bucket (big enough to fit your boot and a few inches of water)
  • boot pick
  • brush
  • disinfectant
  • hand sanitiser
  • water container (or a large re-used water bottle)
  • portable pressure washer (optional, but handy for cleaning bikes or other equipment that won’t fit in a bucket)


Propellar and Cleankill Sanitising Spray are effective against Phytophthora species and other plant pathogens. Note that ‘Cleankill Sanitising Spray’ should be distinguished from ‘Cleankill’, which is a commonly used animal health disinfectant. ‘Cleankill’ has not been tested for its effectiveness against plant pathogens such as Phytophthora species.

We make the following recommendations for using these disinfectants:

  • disinfectants are only effective when sprayed on to clean surfaces, so clear all soil and organic material from the surfaces being disinfected before spraying
  • use Cleankill Sanitising Spray rather than Propellar to disinfect work boots and outerwear, to avoid any damage to their fabric and glue
  • propellar should be used on metal tools to prevent rusting, but it must be stored in a flame-proof container when not in use because of its flammability

COSHH (control of substances harmful to health) and data safety sheets (PDF, 657KB, 18 pages) for both of these products are available and should be consulted before use.

If using disinfectant, you should also include these additional items within your kit:

  • eye protection
  • protective gloves
  • flame-proof container


The number of introductions of tree pests and diseases has increased. It is therefore more important than ever that we all learn how we can help to minimise the risk of further introductions and spread through the effective application of biosecurity measures.

Our biosecurity e-learning package was developed with the Animal and Plant Health Agency, the Arboricultural Association and the British Association for Landscape Industries. It provides background information about biosecurity issues, and clear guidance on the most effective and appropriate biosecurity measures for different situations.

The package can be accessed via the Forestry Commission’s e-learning portal. Before you first use it, you’ll be asked to register and create an account. Once your account is verified you can enrol for the online courses.

The package is divided into five modules:

  • Module 1: Biosecurity awareness
  • Module 2: Biosecurity – dispersal pathways
  • Module 3: Biosecurity measures
  • Module 4: Biosecurity – personal controls
  • Module 5: Biosecurity – import and export requirements for wood packaging material

At the end of each module is a short test to establish your understanding of the subject. The pass mark for each test is 80 per cent, and there is an option to re-take the test if required.

If you have any queries about the e-learning package, contact the Forestry Commission.


‘Keep it Clean’

The Forestry Commission’s ‘Keep it Clean’ campaign is a simple, memorable call to action to everyone to incorporate biosecurity measures into their daily routine. You can support the campaign by downloading the media and tools and using them within your organisation any way you can.

You can also show your support on Twitter by using the Forestry Commission’s ‘Keep it Clean’ Twibbon

Other useful resources

  • UK Plant Health Risk Register Records the main threats to the UK’s plants and trees, and provides prioritised actions to help us improve our defences against them
  • UK Plant Health Information Portal Provides a hub for plant health information, data and resources
  • Plant Biosecurity Strategy Provides a high-level overview of the activity that Defra and the devolved administrations in Scotland and Wales are undertaking to improve plant biosecurity across Great Britain
  • Tree Health Management Plan Sets out the government’s approach to tree health in England, which is in line with the Plant Biosecurity Strategy
  • Tree Health Resilience Strategy Sets out the UK’s plans to reduce the risk of pest and disease threats, and how we will strengthen the resilience of our trees to withstand threats
  • Generic Contingency Plan for Plant and Bee Health in England A working document describing how Defra and operational partners will prepare for, and would respond to, an outbreak of a plant or bee pest or disease in England
  • Countryside Stewardship Apply for tree health grants all year round to restore or improve woodland trees


For tree health and biosecurity related queries:

For e-learning enquiries:

Use Tree Alert to report a suspected tree pest or disease to the Forestry Commission.

Sign up to Tree Health News for the latest information on tree and woodland health.

Follow @ForestryComm on Twitter for updates on forestry grants, regulations and tree health in England.

Published 26 September 2018
Last updated 26 September 2018 + show all updates
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