Tree Health Survey – join in


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

Help scientists monitor and protect our trees and woodlands

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

Did you know?

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

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!

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

Ready to enter your results online?

Once you've completed the survey, simply submit your results
using the online form.

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

Watch: forest biosecurity

Just want to submit a pest or disease sighting?
Use the form below to report a pest or disease without entering full survey data. Please include a photo if you can.

Just submit a pest or disease sighting

Learn more about pests and diseases that can affect trees


Get our free app

Tree ID guides at your fingertips with the OPAL Tree Health Survey app.

Problems entering your results online?

Send your results to:
OPAL, Centre for Environmental Policy,
Imperial College, South Kensington,
London SW7 2AZ.


Downloads – what you need to get involved

Ash leavesTree Health Survey
(PDF, 1.8MB):
Survey instructions and information about the most common UK tree species.
  Tree health survey Field NotebookIdentification Guide
(PDF, 1.2MB):
Recording sheets and information on the pests and diseases to look out for.
  Pest and Disease Guide (PDF, 1.8MB): Pests and diseases that could pose a serious threat to UK trees.

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

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

Looking for the Welsh language survey pack? Visit the Welsh Tree Survey page.


Group Leaders and Schools

Support for group leaders and teachers: Download our group leader support guide, example risk assessment, and our new recording sheets for schools.


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: