Tree diseases in Scotland
Did you know that many trees in Scotland are at risk from pests and diseases? Many species can live for centuries - but infections can cause them to deteriorate and die within a few weeks. Since we manage Scotland’s national forest, a big part of our work involves slowing and preventing the spread of pests and diseases. This makes sure our forests and habitats are preserved, in good health, and available to enjoy for generations to come.
Our forests are threatened by a number of diseases and pests. Here is a round-up of the most common infections, as well as information about how we help prevent their spread.
Phytophthora ramorum (P. ramorum)
This disease mainly affects larch trees. It is one of the biggest threats facing Scotland’s forests. One of the most common symptoms is orange-brown needles in spring and summer - when larch should be green. Infected branches will die - as will the whole tree eventually. The disease is so prevalent in the south and west of Scotland that it cannot be eradicated.
There are ongoing, large-scale felling operations to remove infected trees. Removing infected trees prevents the disease from spreading throughout Scotland’s forests. There is also work being done to prevent the disease spreading north and east.
Ash dieback
First recorded in the UK in 2012, this disease is now widespread throughout Scotland. It is a fungus that attacks the leaves and stem - and affects ash trees. Eventually the disease spreads throughout the tree and blocks the movement of water through the trunk. The tree produces less foliage, ‘dies back’, and becomes brittle.
Ash trees infected with ash dieback can die in just a few years, however some will live much longer. Brittle trees are also dangerous to humans as branches (or entire trees) can fall. We need to manage these trees to prevent health and safety hazards - especially near paths and roads. We work with a number of organisations across Scotland as part of the Ash Dieback Risk Group. This helps us spot the disease and take early action.
Great spruce bark beetles (D. micans)
This is an invasive pest that preys on spruce trees. It tunnels into the bark of living trees and lays eggs. The larvae then feed on the tree and develop - forming galleries that weaken (and can kill) the host tree. It is now well-established in south west Scotland and is moving north.
Spruce is Scotland’s most important timber tree - so managing this pest is essential work. Most commonly we use a biological control method. For this, we release a specific type of beetle that predates on D. micans to help destroy the species.
Why and how we check for tree diseases
Left unchecked, these diseases can cause widespread tree deaths. These can have a knock-on effect, causing several larger issues such as:
- Large changes in wildlife habitats
- Unstable deadwood that can pose a health and safety risk
Late spring and summer is the best time to check our forests for these diseases. Infected trees are more noticeable in this period as they will have reduced canopies or discoloured leaves/needles.
Scottish Forestry carries out surveys for controlled pests and diseases such as those mentioned above. These can take place through ground surveys and helicopter assessments. Our staff also report suspect trees. We aim to take action quickly to slow or stop the spread of these infections.
How we are preparing forests for these threats
As the climate changes we expect new diseases and pests to threaten our forests. Warmer temperatures make it easier for some diseases to move into areas that were previously too cold for survival/breeding. We are adapting our work to create forests that are better able to stand-up to an uncertain future.
We aim to do this by:
- Growing our own saplings in Scotland or sourcing from within the UK
- Removing invasive species that threaten our forests
- Supporting work to find tree species that are resistant to certain diseases
How you can help
Slowing and stopping the spread of diseases and pests is a team effort. We ask all visitors to our forests and land to Keep It Clean.
Before going into a forest make sure your boots, bikes and equipment are free of dirt and debris. This simple action can make a huge difference in the fight against tree disease in Scotland.