Tree diseases and pests

Trees in the United Kingdom are increasingly under threat from a wide range of pests and diseases, which means it is really important when it comes to planting trees that we do our best to plant healthy trees and then keep them healthy. If you are interested in purchasing a tree for planting, visit our PLAN page, which outlines the steps you can take to secure a tree from a nursery with good biosecurity. On this page we will take a further look at tree pests and diseases, exploring other ways you can help protect trees.

Where do tree diseases and pests come from?

As travel and the movement of goods between countries has increased, so has the risk of pests and diseases being spread throughout our natural environment. Climate change also poses a risk to our natural environment, allowing pests and diseases to flourish in new locations and also subjecting our trees to stress as a result of extreme weather patterns, making them more susceptible to attack. With warmer temperatures and changed rain patterns likely to impact tree diseases and pests. While some of these pests and diseases may do little harm in their home countries, without the same environmental factors limiting them in their new location they can be highly destructive.

An example of this is ash dieback, a fungus originating in Asia. In its native environment, the fungus isn’t hugely damaging to its hosts, the Manchurian ash and the Chinese ash. However, because the European Ash hasn’t evolved alongside the fungus, it has no natural defences against it. This meant when it was introduced to Europe 30 years ago, it went on to have a devastating effect on ash populations. According to the Woodland Trust, in the next 10-20 years the UK is predicted to lose 150 million mature trees and 2 billion saplings from ash dieback alone.

How to prevent tree diseases and pests spreading?

Outlined on our PLAN page, one of the best things you can do to prevent the spread of tree pests and diseases is purchasing from a nursery with good biosecurity procedures. If you’re hoping to buy a tree and would like more information on how to do sustainably, visit our PLAN page. It is also important to look after your tree so that it remains healthy and therefore better able to resist attack. Please see further information on our PROTECT page. Don’t forget your own personal biosecurity, keeping your own footwear and clothing clean as you move from site to site, also your gardening tools. And resist the temptation to bring back plant material from travels abroad.

Identifying tree diseases and pests

Another key way we can ensure our trees are healthy is by learning how to identify tree pests and diseases. The Forestry Commission and Animal and Plant Healthy Agency have put together this overview on how to identify common tree pests and diseases. Once you have identified the pests, you can seek advice on the next steps to take as outlined on this Forestry Commission page. There you can select the identified pest or disease for detailed information, including what action you can take. Further information and contact details if you need to seek further advice is available on the UK Government’s tree pests and diseases page.