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TreeAlert is the online reporting tool for tree pests and diseases, managed by Forest Research with funding from Defra, Forestry Commission, Scottish Forestry and Welsh Government. It is a valuable aid, allowing you to quickly report any suspect findings of tree pests and diseases which are of concern in Britain.

Help us gather information about the health of the nation’s trees, woodlands and forests by reporting signs of dangerous tree pests and diseases using TreeAlert.

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Submit a report



The information from TreeAlert reports will support important tree health monitoring and surveillance work, contribute to ongoing scientific research in this field and, ultimately, support efforts to protect the nation’s trees.

What happens to TreeAlert reports

What do you need to do to make your report

How to take photographs

Diameter of a tree

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What do you need to make your report

What information you will need to provide to submit a TreeAlert report

In order to submit a useful report of a tree health problem through TreeAlert you will be taken through a series of screens where you will be asked a number of questions about your observation. The more information you can provide, the more useful your report will be.

This page helps you to prepare to submit a report by giving an overview of the reporting process and a list of essential information that you will need to provide.

Information about you – we need your contact details in case we require additional information. You will need to provide:

  • Your name (first name and last name)
  • A valid email address
  • Indication of level of knowledge/experience (options provided)

You have the option to create an account. You do not have to create an account to submit a report however it is very quick and means when you submit future reports the site will remember your contact details and level of experience. You will also be able to view previous report submissions.

Information about your observation – there are a number of screens dedicated to recording essential information about the tree health problem you are reporting. You will be asked to provide the following:

  • The date of your observation
  • The type of location in which your observation was made (a drop-down list is provided)
  • The location of the problem you are reporting, and either a grid reference (a 10 figure grid reference is preferable, but we will accept a 6 or 8 figure grid reference without spaces) / point on a map or a postcode. If you are using the map tool, make sure you zoom in to the required level to place a point accurately. Our ability to locate the affected tree(s) accurately is very important and why we would recommend you use the map/grid reference over the postcode option
  • The number of trees affected, their approximate age and size measured as trunk/stem diameter
  • The type of tree affected (conifer or broadleaf), its common name and species (drop-down lists are provided)
  • Information about the problem you have observed, including location on the affected tree (crown, stem or base) and the nature of the symptom(s) (drop-down lists are provided). NB you can report more than one symptom on any affected tree(s)
  • Photographs of your observation. Ideally we would like three good quality photographs showing
    • (1) the affected tree(s) in context,
    • (2) the problem/symptom in context, and
    • (3) the details of the symptom.

How to take photographs

Taking good photos for your TreeAlert reports

Pictures of an affected tree can be more useful than a lengthy written description of the symptoms which it displays but only if the photos are taken well and they illustrate the correct range of features.

How to take your photos:

  • Make sure that the pictures are clear enough to illustrate the point that you intend to show.
  • Take your pictures in the best possible natural light, but use flash if needed, to avoid both “camera shake” (blurry pictures) and photos which are too dark to illustrate the features that you want to show.

What to photograph:

  • Although it’s tempting to concentrate on taking detailed images of the symptom(s) which the tree displays, it’s just as important to show the entire tree and its surroundings (the tree in context) and to how the symptoms are distributed on the affected parts of the tree (the symptom in context) as it is to illustrate the symptom up close (the detailed symptom). We recommend that you take several images of each type and upload only the best one in each category (a total of 3 images). Here are images of two different trees suffering from different problems which illustrate the type of image that we’re looking for in each category (each photo is accompanied by a description of what can be seen by careful examination of the picture):

Tree in context

Should show the entire tree and its immediate surroundings. This provides information on the nature of the site, the conditions in which the tree is growing, whether any other plants in the vicinity are showing signs of disease or damage, and a range of other factors which may have had an impact on the health of the tree. It may also provide an overall indication of how symptoms are distributed on the crown, stem or stem base.

trees in context with wording.jpg

Symptom in context

Should illustrate how the symptom is distributed locally on the affected part(s) of the tree. This type of image helps to indicate the severity of the symptom(s) and which part(s) of the tree may be affected by a problem (e.g. browning of leaves may be the result of damage to the shoot or branch which holds them rather than direct damage to the leaves themselves by a foliar pest or pathogen). It may also help to identify the species of tree concerned if there is any uncertainty about this.

symptom in context with wording.jpg

Detailed symptom

Should show the fine details of the symptom as clearly as possible. This type of image helps to indicate the small-scale distribution of dead and live tissue and any associated discolouration on the affected part of the tree or may illustrate the pest or pathogen itself. Where the symptom is variable, it can be useful to include several affected parts (such as leaves or needles) in a single picture. Placing an object in the frame to indicate the scale at which the image was taken can sometimes be useful.

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Diameter of a tree

Diameter of a tree

What are we looking for when we ask for the diameter of a tree? The measurement that we want is the approximate distance across the centre of the trunk as shown in the diagram below; in other words the thickness of the trunk.

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Tree Alert – Contact us

Please contact TreeAlert to report any technical problem encountered whilst submitting a TreeAlert report.

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