Blue-grey worm

Tree health survey

The best time to do this survey is between May and September.

Help scientists monitor and protect our trees, forests and woodland

Ecologist Mike Dilger introduces our guide to taking part in the tree health survey

Trees are vital – bringing nature into urban areas, supporting the rural economy, providing food and habitats for wildlife, and helping to combat climate change.

However, our trees are under threat. The number of pests and diseases attacking them has increased in the last few years.

UK governments have already stepped up their activity to protect trees, and you can help too, by taking part in the OPAL tree health survey, designed in collaboration with Forest Research and FERA.

How to take part

Step 1 – Download and print the survey documents in English or in Welsh (ideally in colour).

Step 2 – Find a site with safe access to one or more broadleaved trees and start surveying!


Did you know?

Knopper galls, which can form on acorns, are caused by a tiny gall wasp called Andricus quercuscalicis. This pest first arrived in southern England in the 1950s and has now invaded most of the UK.

Step 3 – Tell us what you find using our simple online form.

Ready to enter your results online?

Just want to submit a possible pest or disease sighting?

Use the form below to tell us about a pest or disease you've spotted outside the survey. Please include a photo if you can.


OPAL logoA good biosecurity routine can reduce the risk of spreading diseases and invasive species.

Watch this video to find out more about forest biosecurity measures

Problems entering your results online?
Send your results to: FREEPOST RSCH-CHYJ-HYYC, OPAL, Centre for Environmental Policy, Imperial College, South Kensington, London SW7 2AZ.


Downloads – what you need to get involved

Ash leavesField guide:
Survey instructions and information about Oak, Ash and Horse Chestnut trees
  Tree health survey Field NotebookField notebook:
Recording sheets and information on 12 important pests and diseases to look out for
  Citrus Longhorn BeetleMost Unwanted
Guide: Six pests and diseases that could pose a serious threat to our trees


Tree ID guide and poster (PDF, 2.4MB) – a guide for your wall to help you identify common UK tree species


Electronic field record sheet for multiple trees (Excel, 52KB) – record data on your laptop or tablet for up to 50 trees


Printable field record sheet for multiple trees, Activity 1 (Excel, 42.5KB) – record data by hand for up to 30 trees


Printable field record sheet for multiple trees, Activity 2 (Excel, 45KB) – record data by hand for up to 30 trees



Find out how the survey fits into the National Curriculum in England (PDF, 53KB)

Explore how the survey fits into the curriculum in Scotland (PDF, 126KB) and download an activity guide for teachers (PDF, 259KB)


You may download these documents for use in the context of the OPAL project only. All other rights are reserved.



Policy and regulation
To find out about the action being taken by UK governments and their agencies to protect our trees from pests and diseases, visit: