Guidance

Identify a tree pest or disease: overview

Find out about pests and diseases that could be affecting your trees.

Monitoring tree health and protecting our trees, woods and forests from pests and diseases is an increasingly important part of sustainable tree and forest management. This means you need to be able to identify specific pests and diseases to tackle any obvious problems. Once you know what’s affecting your trees, you can find advice on what action to take.

Specific tree pests and diseases

If you know the name of the tree pest or disease affecting your trees, see the Forestry Commission guidance giving detailed information on specific tree pests or diseases known to be present in the UK. You can also find out about those that pose a potential risk to the UK but are not present yet.

Identify by tree species

If you’re unsure what’s causing the problem, use the alphabetical table below to narrow down the options for the relevant tree species and find out which pests and diseases can affect it.

Once you’ve found the likely culprit for your tree species, you can read Forestry Commission guidance giving detailed information on that specific pest or disease and how to deal with it.

A

Tree species Pest or disease names
Alder (Alnus) Asian longhorn beetle, Phytophthora alni
Apple (Malus domestica) Citrus longhorn beetle
Ash (Fraxinus species) Asian longhorn beetle, chalara ash dieback, emerald ash borer

B

Tree species Pest or disease names
Beech (Fagus species) Asian longhorn beetle, Citrus longhorn beetle, Phytophthora kernoviae, Phytophthora ramorum
Birch (Betula species) Asian longhorn beetle, Citrus longhorn beetle

C

Tree species Pest or disease names
Cedar (Cedrus species) Pinewood nematode, Sirococcus blight
Cherry (Prunus species) Asian longhorn beetle, citrus longhorn beetle
Citrus trees (Citrus species) Xylella fastidiosa
Common ash (Fraxinus excelsior) Asian longhorn beetle, chalara ash dieback, emerald ash borer
Corsican pine (Pinus nigra) Dothistroma needle blight
Cypress (Cupressus species) No significant threats

D

Tree species Pest or disease names
Douglas fir (Pseudotsuga menziesii) Phytophthora ramorum, pine-tree lappet moth

E

Tree species Pest or disease names
Elder (Sambucus nigra) No significant threats
Elm (Ulmus species) Asian longhorn beetle, citrus longhorn beetle, Dutch elm disease, elm zig-zag sawfly, Xylella fastidiosa

F

Tree species Pest or disease name
Field maple (Acer campestre) No significant threats

G

Tree species Pest or disease name
Grand fir (Abies grandis) No significant threats

H

Tree species Pest or disease names
Hawthorn (Crataegus monogyna) No significant threats
Hazel (Corylus species) Asian longhorn beetle, citrus longhorn beetle
Hornbeam (Carpinus species) Asian longhorn beetle, citrus longhorn beetle
Horse chestnut (Aesculus hippocastanum) Asian longhorn beetle, citrus longhorn beetle, horse chestnut leaf miner, Phytophthora ramorum

J

Tree species Pest or disease name
Juniper (Juniperus communis) Phytophthora austrocedri

L

Tree species Pest or disease names
Larch (Larix species) Phytophthora ramorum, pinewood nematode, pine processionary moth
Lawson cypress (Chamaecyparis lawsoniana) Phytophthora austrocedrae, Phytophthora lateralis
Lodgepole pine (Pinus contorta) Dothistroma needle blight, pinewood nematode, pine processionary moth

M

Tree species Pest or disease names
Maple (Acer saccharum) Asian longhorn beetle, citrus longhorn beetle, sweet chestnut blight
Mountain ash or rowan (Sorbus aucuparia) Asian longhorn beetle

N

Tree species Pest or disease names
Narrow-leaved ash (Fraxinus angustifolia) Asian longhorn beetle, chalara ash dieback, emerald ash borer
Noble fir (Abies procera) No significant threats
Norway spruce (Picea abies) Great spruce bark beetle, 8-toothed spruce bark beetle, pine-tree lappet moth, pinewood nematode

O

Tree species Pest or disease names
Oak - holm (Quercus ilex) Sweet chestnut blight, oak pinhole borer, oak processionary moth, Phytophthora kernoviae
Oak - northern red (Quercus rubra) Xylella fastidiosa
Oak - pedunculate or ‘English’ (Quercus robur) Acute oak decline, Asian longhorn beetle, sweet chestnut blight, oak pinhole borer, oak processionary moth, Phytophthora kernoviae, Xylella fastidiosa
Oak - sessile (Quercus petraea) Sweet chestnut blight, oak pinhole borer, oak processionary moth
Oak - turkey (Quercus cerris) Phytophthora ramorum
Olive (Olea europaea) Xylella fastidiosa

P

Tree species Pest or disease names
Pear (Pyrus species) Citrus longhorn beetle
Pine - Corsican (Pinus nigra) Dothistroma needle blight
Pine - lodgepole (Pinus contorta) Dothistroma needle blight, pinewood nematode, pine processionary moth
Pine - Scots (Pinus sylvestris) Dothistroma needle blight, pine-tree lappet moth, pinewood nematode
Plane (Platanus species) Asian longhorn beetle, citrus longhorn beetle, Xylella fastidiosa
Plum (Prunus species) Asian longhorn beetle
Poplar (Populus species) Asian longhorn beetle, citrus longhorn beetle

R

Tree species Pest or disease name
Rowan or mountain ash (Sorbus aucuparia) Asian longhorn beetle

S

Tree species Pest or disease names
Scots pine (Pinus sylvestris) Dothistroma needle blight, pine-tree lappet moth, pinewood nematode
Spruce - Norway (Picea abies) Great spruce bark beetle, 8-toothed spruce bark beetle, pine-tree lappet moth, pinewood nematode
Spruce - Sitka (Picea sitchensis) Great spruce bark beetle, 8-toothed spruce bark beetle, pine-tree lappet moth, pinewood nematode, Phytophthora ramorum
Sweet chestnut (Castanea sativa) Sweet chestnut blight, Oriental chestnut gall wasp, Phytophthora ramorum
Sycamore (Acer pseudoplatanus) Asian longhorn beetle

W

Tree species pest or disease names
Western hemlock (Tsuga heterophylla) Sirococcus blight
Western red cedar (Thuja plicata) Sirococcus blight
Willow (Salix species) Asian longhorn beetle, citrus longhorn beetle

Y

Tree species pest or disease name
Yew (Taxus baccata) Phytophthora lateralis

Note: this list of trees is not exhaustive.

Request a diagnosis

The information in the table above is not exhaustive. You may discover a different pest or disease attacking your trees and you should report it or request a diagnosis from Forest Research’s Tree Health Diagnostic and Advisory Service. There might be a fee for this service.

Published 26 September 2018