>
Home /Help & Advice / Pests and Diseases

Pests and Diseases

TreeAlert and TreeCheck

Reporting Pests & Diseases

There are many invertebrates like mites and nematodes, bacteria, phytoplasmas, water molds, plants (mistletoes) and viruses that can cause damage and need to be avoided through biosecurity measures.

Learn how to report signs of dangerous tree pests and diseases.

Cases of ill health found in trees across the UK and Ireland should be reported through:

For the UK the Forestry Commission’s TreeAlert which can be found at:

treealert.forestresearch.gov.uk

In Ireland and Northern Ireland use TreeCheck which can be found at: www.treecheck.net

www.treecheck.net

ADVERTISEMENT

View the Introductory Guide to Young Tree Establishment Sieries

Download the Pests and Pathogens Poster

Download the Application of Biosecurity Poster

Acute Oak Decline – Oak

Acute Oak Decline –
Acute Oak Decline (AOD) is a disease affecting several thousand native oak trees in Britain. It is considered to have first occurred in Britain 30-35 years ago. It mainly affects pedunculate oak (Quercus robur) and sessile oak (Quercus petrea), however other species of oak can also be affected.

Downloads & Links

Emerald Ash Borer Agrilus planipennis Ash

Emerald Ash Borer – Agrilus planipennis
Emerald Ash Borer (Agrilus planipennis) (EAB) is an exotic beetle which causes significant damage to ash trees (Fraxinus species). A native of eastern Asia, it is not known to be present in the UK.

Downloads & Links

Asian Longhorn Beetle Anoplophora glabripennis Many

Asian Longhorn Beetle – Anoplophora glabripennis
Asian Longhorn Beetle (ALB), Anoplophora glabripennis, is a native of China and the Korean peninsula, and poses a serious threat to a wide range of broadleaved trees. It has caused extensive damage to trees in the USA and Italy since being accidentally introduced there in recent years.

Downloads & Links

Elm Zig-Zag Sawfly Aproceros leucopoda Elm & Others

Elm Zig-Zag Sawfly – Aproceros leucopoda
The Elm Zig-Zag Sawfly, Aproceros leucopoda, has now been confirmed in Britain following a rapid expansion across Europe from eastern Asia. This page briefly describes the biology of the species, the risk it poses to elms in Britain, and its identification. To report a sighting of this species, please use Tree Alert.

Downloads & Links

Oak Wilt Ceratocystis fagacearum Oak

Oak Wilt – Ceratocystis fagacearum
Ceratocystis fagacearum (C. fagacearum) is a destructive fungus which causes wilt in oak trees in eastern and mid-western states of the United States. It causes extensive damage, particularly to species in the ‘red’ oak group (Quercus section Lobatae; syn. Erythrobalanus), but it can also damage ‘white’ oaks (Quercus section Quercus).

Downloads & Links

Canker Stain of Plane Ceratocystis platani London Plane

Canker Stain of Plane – Ceratocystis platani
The ascomycete fungus Ceratocystis platani causes canker stain, also known as plane tree wilt, on several plane species, including London plane (Platanus x acerifolia) and its parents, P. orientalis and P. occidentalis.

Downloads & Links

Sweet Chestnut Blight Cryphonectria parasitica Sweet Chestnut

Sweet Chestnut Blight – Cryphonectria parasitica
Sweet chestnut blight is caused by a fungus of Asian origin called Cryphonectria parasitica. Several cases of the disease affecting sweet chestnut trees have been found in England since 2011.

Downloads & Links

Red Band Needle Blight Dothistroma septosporum Pine

Red Band Needle Blight – Dothistroma septosporum
Dothistroma Needle Blight (DNB) (Dothistroma septosporum), also known as Red Band Needle Blight because of the colourful symptoms it shows on pine, is an economically important disease of conifers. It causes premature needle defoliation, resulting in loss of yield and, in severe cases, tree death.

Downloads & Links

Chalara Dieback of Ash Hymenoscyphus fraxineus Ash

Chalara Dieback of Ash – Hymenoscyphus fraxineus
Chalara dieback of ash is a disease of ash trees caused by a fungus called Hymenoscyphus fraxineus. It is particularly pathogenic to European ash, fraxinus excelsior.

Downloads & Links

Larch Tree Disease Phytophthora ramorum Larch & Others

Larch Tree Disease – Phytophthora ramorum
Phytophthora ramorum (P. ramorum) is a a fungus-like pathogen called a water mould. It causes extensive damage and death to a wide range of trees and other plants.

Downloads & Links

Shoot Blight of Cedar Sirococcus tsugae Cedar

Shoot Blight of Cedar – Sirococcus tsugae
In recent years severe shoot blight and defoliation of Atlantic Cedar has been reported from a range of locations in Britain. In late autumn 2013, samples from affected trees were received by Forest Research and the fungus Sirococcus tsugae was identified as being consistently associated with these symptoms.

Downloads & Links

Pine Processionary Moth Thaumetopoea pityocampa Pine

Pine Processionary Moth – Thaumetopoea pityocampa
Pine Processionary Moth (PPM), Thaumetopoea pityocampa, is not currently known to be in the UK. PPM has been extending its range across Europe, moving northwards through France since the 1990s.

Downloads & Links

Oak Processionary Moth Thaumetopoea processionea Oak

Oak Processionary Moth – Thaumetopoea processionea
Oak processionary moth (Thaumetopoea processionea, OPM) was first accidentally introduced to parts of South East England in 2005. European Union legislation was introduced in 2014 that recognises unaffected areas of the UK as being a ‘protected zone’.

Downloads & Links

Phony Disease of Peach Xylella fastidiosa Many

Phony Disease of Peach – Xylella fastidiosa
Xylella fastidiosa, also known by Pierce’s disease of grapevine, is a bacterium which causes disease in a wide range of woody plants, such as citrus and olive trees and in grape vines. Whilst not known to be present in the UK yet, it has the potential to infect several species of broadleaf trees.

Downloads & Links

KEY: (As of Autumn 2018)

‌
  Not Currently Present
‌
  Already Present

More information

The Forestry Commission has also produced the following information about pests and diseases and associated biosecurity. Click a link below to find out more.

For more information on pests and diseases and how we can help reduce their spread, take a look at their website: www.gov.uk/guidance/prevent-the-introduction-and-spread-of-tree-pests-and-diseases

Information contained on this page are © copyright of the Forestry Commission and are used with their permission.

Massaria Disease of Plane

Oriental Chestnut Gall Wasp

Phytophthora austrocedri

Phytophthora lateralis

Ips typographus

Arboricultural Association celebrating 60 years

Arboricultural Association

The Malthouse, Stroud Green, Standish, Stonehouse, Gloucestershire GL10 3DL

Arboricultural Association Ltd. A company registered in England at The Malthouse, Stroud Green, Standish, Stonehouse, Gloucestershire GL10 3DL, UK. Company number 4070377.
+44 (0)1242 522152  |  admin@trees.org.uk

The Arboricultural Association is a registered charity no. 1083845.

Copyright © 2025 The Arboricultural Association. All rights reserved.

 
 
‌

Follow Us

 
Visa Credit payments supported by WorldPay Visa Debit payments supported by WorldPay Visa Electron payments supported by WorldPay Mastercard payments supported by WorldPay Maestro payments supported by WorldPay
WorldPay Payments Processing
 

Click to donate via PayPal

‌

The home of tree care