Tree Diseases: Taking Care of London’s Trees

Trees are precious. The Royal Parks host around 170,000 of them, including 250 varieties and 1,500 veteran and ancient trees.

Tree-mendous trees

Not only do they provide a beautiful backdrop for city dwellers, trees also provide habitats for thousands of species: fungi, insects and mammals, such as bats and birds. They help to trap dust, absorb pollutants and remove carbon dioxide – helping slow global warming. They also cool urban air temperatures and prevent flooding by absorbing storm water.

Threats to the UK’s trees

However, like all living, dynamic species, trees do not live forever. They become weakened and damaged by age, weather, pollution and through infections caused by tree pests and diseases.

There are a number of common tree pests and diseases which currently threaten trees across London’s green spaces, including The Royal Parks - along with the UK’s woods, forests and beauty spots. There is also a strong likelihood that new pests and diseases will make their way over to the UK in the future.

The Royal Park’s expert tree care

The Royal Parks employs a team of expert tree specialists who inspect and assess the parks’ trees regularly. The team carries out a combination of habitat management to promote ecology and wildlife diversity, risk management to ensure the safety of visitors, and visual management to keep the trees and the parks looking their best.

They monitor and respond to any changes to the health of trees currently and plan ahead in order to ensure that the treescape is resilient in the future – with special consideration to the potential arrival of new trees diseases to the UK and in the parks, to ageing trees and other pressures such as climate change and pollution.

Our experts identify the best ways to boost trees’ health so they can fight potential infections better. For example, compost ‘tea’ - a ‘consommé’ of beneficial bacteria, social microorganisms and fungi – is sometimes added to compost. This mixture of ‘helpful’ fungi and microorganisms supercharges the compost which is added to soil to help trees resist and fight infections. Material called mulch may also be added to the surface of soil to preserve soil moisture and improve soil health.

But it is inevitable that some trees will be unable to fight an infection despite the best care. Sometimes, if a tree is unable to fight off a disease, it may be necessary to remove branches that have become damaged or have died. As a last resort, if the damage is insurmountable, the whole tree may need to be removed.

Planning for the future

Between two to three hundred new trees are planted every year across the parks for a variety of reasons – for example improving a local habitat - and a number of these are replacements for losses.

The Royal Parks contain a high proportion of native species with a rich history of rare and unusual species, varieties and specially cultivated examples. This is sustained where possible when planting new trees, to maintain diversity.

When planning ahead, our experts take into account the characteristics of each tree species such as the growth pattern, life expectancy, structure and strength of the wood and which ones are susceptible to particular infections. Our team identifies the most appropriate species for each park and ensures a disease-resilient landscape to be enjoyed for generations to come.

Other potential future tree pests and diseases

There have been no reported outbreaks in the UK of any of the other possible future tree problems such as canker stain of plane (currently in central France), emerald ash borer beetle (currently in Russia) or the bacterium Xylella fastidiosa (southern in Italy and Spain), but we remain vigilant and ready to respond.