Biological damage

There are a range of different biological organisms that can cause damage to woodland. This damage can be economic in nature (damaging the value of timber), or ecological (damaging the biodiversity). In either case it may be appropriate to manage the habitat and species in a woodland to provide the greatest benefit.

If you find that trees in your woodland are dying, and you suspect that they may be diseased, then the Forest Research Tree Health Diagnostic and Advisory Service is able to test samples. Further details of their service and rates are available here. There is also a Twitter feed for new information on pest and diseases here.

Inspections of trees and woodland by Forestry Commission plant health inspectors play an important role in efforts to manage outbreaks of pests and diseases. Guidance to plant health inspectors can help you understand what to expect if an inspector needs to visit your premises.

'Biosecurity' (short for biological security) refers to measures taken to protect, or keep secure, one group of biological organisms - in this case trees, woods and forests - from other, harmful biological organisms, such as disease-causing pathogens such as bacteria, viruses and fungi, certain insects, and invasive plants and animals. There is a guide to biosecurity best practice available from the Forestry Commission here.

Insect Pests

Bacterial, Viral and Fungal Pathogens

Invasive Species and Weeds

Damage Caused by Mammals


Insect Pests

A significant number of pests can affect trees in the UK. Many of them have limited areas of spread and affect specific species, but due to the effects of climate change and increases in the international trade in woody plant material, it seems likely that the number of different insect pests affecting trees in the UK will increase. The Forestry Commission Plant Health inspectors have published a list of the most significant new threats in the UK here, but the main insect threats are:

  • Great spruce bark beetle (Dendroctonus micans)
  • Horse chestnut leaf miner (Cameraria ohridella)
  • Oak pinhole borer (Platypus cylindrus)
  • Oak processionary moth (Thaumetopoea processionea)
  • Pine tree lappet moth (Dendrolimus pini)

Forest Research has also produced a list of Tree Pest and Disease alert and advisory notices available here

Back to top


Bacterial, Viral and Fungal Pathogens

There are a broad spectrum of different diseases that can affect trees in the UK. Many have been established in the British Isles for hundreds of years and have become part of the natural ecosystem. However, there have been an increasingly large number of new pathogens detected in recent years. The Forestry Commission Plant Health inspectors have published a list of the most significant new threats in the UK here, the main pathogens are:

  • Acute oak decline
  • Bleeding canker of horse chestnut (Pseudomonas syringae)
  • Phytophthora spp.
  • Red band needle blight (Dothistroma septosporum)

If you are concerned, or need help identifying a disease in trees, then contact Forest Research Tree Health Diagnostic and Advisory Service here. Forest Research has also produced a list of Tree Pest and Disease alert and advisory notices available here.

Biomass can be a suitable end use for diseased material but there may be precautions and restrictions that apply when transporting this sort of material. In particular, there are limitations on handling of Phytophthora infected material and only authorized companies may deal with this material. If you have any questions regarding plant health, then contact either the Forestry Commission plant health service (details here) or Forest Research (details here).

Back to top


Invasive Species and Weeds

There are a large number of invasive species in the UK. While very few of them will harm well established trees, many of them will successfully out-compete newly planted trees and can cause a significant negative impact on woodland biodiversity. This may be a particular issue in woodlands that have been managed for game shooting as two invasive species; rhododendron and snowberry were often planted as game-bird cover. There is a useful overview of invasive species at naturenet.

NB Ivy does not harm living trees, and shouldn't be considered to be a risk to healthy woodland. The only time trees are in danger from ivy growth is if the tree is already rotten and cannot take the aditional weight, or if for some reason the ivy overshadows the tree's crown.

Injurious weeds act of 1959

A number of species are covered in the injurious weeds act of 1959. Under this act it is an offence to allow particular species to spread from your land onto a neighbouring property.

  • Common ragwort
  • Spear thistle
  • Creeping or field thistle
  • Broad-leaved dock
  • Curled dock

this is covered in detail on the .gov website here.

Wildlife and countryside act 1981

The release of a number of invasive species is also controlled by the Wildlife and Countryside Act 1981 this includes a large number of animal and plant species including: rhododendron, Himalayan balsam, giant hogweed and Japanese knotweed. Further information is available on the DEFRA website here.

Back to top


Damage Caused by Mammals

There is a wide variety of different mammalian species in the UK which can cause damage to trees. These species range in scale from the edible dormouse (glis glis) to deer and domestic livestock, leading to varying degrees and types of damage. Damage to trees from mammals usually falls into two categories: browsing (eating leaves, and buds) and bark stripping.

Forest research have a useful guide for determining which mammals may be causing damage available here. The also have a list of methods to restrict and control mammal damage in woodlands here (and further reading here.)

Back to top