This blog is the final part in our celebrations of 10 years of Observatree. It coincides with the end of National Tree Week, during which many of our Observatree partner and supporting organisations were busy with activities and campaigns such as ‘Grow a tree in 23’. From an Observatree perspective, we would also advocate ‘Protect a tree in 23’ (and beyond) and promote tree health, monitoring and reporting. As we have hopefully demonstrated over the last ten years (and highlighted over the last 10 weeks), citizen scientists can help to make a difference in protecting our trees, woods and forests.


Ten years of data collection by Observatree volunteers

In the 10 years since Observatree began, our volunteers have submitted more than 22,000 tree health reports. Thankfully, 75% of these relate to healthy trees; whilst 15% of the submissions are for pests or diseases that are a priority for the project and on which the volunteers have received training. But a further 10% of submissions from the volunteers are on other suspected pests, diseases or unknown causes.


To date, Observatree volunteers have reported many suspected sightings of our Priority pests and diseases. These include:


Some of our volunteers have been with the project since it began. Many submit dozens of tree health reports a year, often whilst visiting other parts of the UK. One volunteer who lives in the Midlands, recently submitted our first reports (thankfully for healthy trees) from the Shetland islands. Other volunteers have passed through the project and during the last 10 years, more than 600 individuals have volunteered for the project. Whilst we aim to maintain an active network of 200, those who are no longer part of the project retain the knowledge of tree health awareness and know how and where to access information and submit reports.

These maps show the distribution of tree health reports on ash submitted by Observatree volunteers to the end of 2022. We are still collecting data form 2023 and will add those to the maps early in 2024. One map shows the years over which the ash reports were submitted, the other shows if they were healthy or had a suspected pest or disease (usually chalara).

A collaborative success

When Observatree was formed, there were nine partners collaborating on the project. 10 years later, we continue to have the same partners at the core of the project, and this is a major part of Observatree’s success. All the partners bring something different to the project, ranging from tree health expertise, volunteer management experience, access to land for our volunteers or collaboration with communicating out tree health messages. But the shared concerns around tree health have forged a strong partnership that has helped to ensure the continuation of Observatree.

In recent years, we have expanded our networks, to work with several different organisations that share our desire to help protect the UK’s trees. Some, are helping to share tree health information and Observatree updates and resources through their networks. Others are also facilitating access to their land, allowing Observatree volunteers to carry-out their tree health surveys.

‘Thank you’ to all of our Partners and Associates for your continued support of Observatree.

Observatree is not the only citizen science project with an interest in tree health and we are also keen to collaborate with others in supporting and promoting the important role that everyone can play in tree health monitoring. During 2023, we linked with the Check a sweet chestnut campaign, and many Observatree volunteers have submitted reports on sweet chestnut trees in their area.

2023 and beyond

Observatree has become an important part of Britain’s approach to tree health. Whilst the Observatree volunteer network continue to do their routine monitoring and surveillance, the network can also be called upon to support official activities.  The project has become a widely recognised name in promoting tree health to wider audiences. This was reflected this year when Observatree was highlighted in Defra’s 2023 Plant Biosecurity Strategy for Great Britain. As this Strategy aims to have a society that is increasingly aware of biosecurity and risks to plant health, initiatives such as Observatree provides an example of how different organisations and members of the public can combine to strengthen the protection of our plants and trees.


In the next few years, it is likely that more tree pests or diseases will continue to head towards or arrive on our shores. The need for continued awareness, surveillance and reporting will not be going away. We will continue to maintain our network of trained volunteers and seek opportunities to work with others. We will continue to review our Priority pest and disease list on an annual basis and update our training resources accordingly.


If you would like to help the work of Observatree, why not see one of our Host of the Month blogs to learn about a species of tree and some associated pests and diseases of concern. You can then add any trees of that species in your area to our TreeAlert system. As a registered user, it is possible to record the healthy looking as well as any with possible pests or diseases. If you would like to test your tree health knowledge, you can either do so via the host of the month blogs, or this short quiz hosted by the British Society of Plant Pathology.