A Plea From The Trees – How You Can Help

clean boot

Going on a walking holiday this summer or planning a visit to the South Downs? If so, be sure to pack your sunscreen, a hat, poles…and give your boots a good wash before you go. Wash? Yes, you read that correctly. While a wipe over with a cloth and dab of Nikwax might protect your boots from wear and tear, it will unfortunately do little to safeguard the landscape you are looking forward to exploring.

Sadly, like people, trees are also vulnerable to pests and disease. Just as we battled Covid, so they are currently fighting an unprecedented attack from biosecurity threats. The Royal Forestry Society has recently reported that over one third of Europe’s 454 native tree species are at risk. While new pests and diseases are mainly arriving in the UK through imports it is the soles of our shoes that are providing an easy way for them to spread out around the country. Washing our shoes is therefore a very small ask in terms of protecting our country’s precious biodiversity and landscape.

Tree Health Check

To understand more about the problem of tree health, I recently went for a walk with Dr Andy Moffat.  Andy is an experienced environmental and forestry scientist. Now an environmental consultant, he was formerly Head of the Centre for Forestry and Climate Change at the Alice Holt Forestry Research Centre, near Farnham, in the north western corner of the park. As well as undertaking research on the likely effects of climate change on woodlands and forests, the Centre also has responsibility for tree pests and diseases.

Our walk was timely, as Andy had recently returned from New Zealand. As an island nation highly dependent on agriculture and forestry it is well known for taking biosecurity very seriously. Fearful that his boot cleaning might not pass muster with New Zealand border control, Andy had deliberately not used his brand-new boots until reaching the country. These had now been freshly cleaned for our walk around Cowdray’s woodlands, as had mine.  


Dr Andy Moffat


Pests & Diseases

We started by following the Race, a wide Sweet Chestnut lined avenue north of Easebourne, outside Midhurst. The trees, all veteran and rather cancerous looking, perfectly set the scene for our chat. Andy explained that over the last 40-50 years the UK has gone from having a tree disease or two a decade, to now almost one a year. Ones you might have heard about include Ash Dieback, Sudden Oak Death, Red Band Needle Blight, Horse Chestnut Leaf Miner, and various forms of Phytophthora, which affects Chestnut, Larch, Beech, and Sycamore. I mentioned remembering Dutch Elm Disease from my childhood but was corrected. “That disease is no relic of the past” Andy said, “the beetle which caused Elm Disease is still very much with us, we just don’t notice it because it takes the trees out long before they reach maturity.”


veteran sweet chestnut


Signs in woodlands warning about Phytophthora (like the one below) are unfortunately becoming a common sight. However, without better understanding of these diseases, their causes and consequences, the information fails to resonate with members of the public. With an expert to hand, I asked Andy to provide some background to the problem.


tree disease poster

A Balancing Act – Nature vs Consumerism

He said that there are several factors behind the recent proliferation in tree disease, but imports are the biggest problem. However, as the world’s third largest importer of timber, he cautioned that the UK always has to delicately balance the needs of fibre/timber security against that of biosecurity. “Unfortunately”, he said, “we all love our oak furniture and wooden kitchen cabinets, and border control can’t realistically check every single pot or piece of bark for microbes and insects. We have a operate a risk-based system.”

Inevitably, another big part of the problem is climate change, as it is well-known that ecosystems don’t function in isolation. Phytophthora, for one, thrives in wet conditions so will perhaps become a greater problem after the rain of this past winter. Lastly, Andy explained that as many of our forest stands are based on only one or a few tree species, this makes them more at risk from the effects of pests and diseases, should they target a particular tree species.

The Problem of Monocultures

Our route demonstrated the monoculture problem, first weaving its way through dense plantations of Larch, then coming out into an expanse of recently coppiced Sweet Chestnut. We stopped amongst the Chestnut stools to chat with the coppicer. He was bundling up the brash for use in a salt flat creation scheme. Every piece of wood, no matter its size, has value. However, while very tidy and uniform, the bundles were a reminder of the unsophisticated nature of forestry work. Andy picked up on this when I asked him to explain the methods foresters might employ to combat pathogens threatening existing woodlands. He said that the options are crude. It comes down to a choice between leave, thin or fell. In more remote parts of the world foresters spray with pesticides, but this is rarely an option in the UK due to the risk of chemicals entering water courses and the wider environment.


coppiced sweet chestnut


Building In Resilience

Down the line, it is clear that foresters also have a fourth option, building in resilience by changing what and how they plant trees, either when establishing new woodlands or in restocking after felling for timber extraction. However, this will take time as trees don’t grow fast. In the meantime, it is down to responsible walkers, like us, to play a part in halting the spread. Obviously, washing boots regularly and encouraging others to do the same is something we can all do.


bundles of sweet chestnut


Citizen Science

However, if you have an interest in conservation, you might also like to participate in a citizen science project which Andy mentioned called Observatree. Hats off to the person who came up with that name! Observatree is a tree pest and disease resource website, where you can learn how to identify both the pests and evidence of their activity.

It is connected to a second website, Tree Alert, where you can record signs of tree ill-health you observe on walks. Scientists review this information and follow up, if necessary. The idea is simple. The more eyes out spotting threats, the quicker experts can get on top of them. Simple observations like this can really make a big difference. Back in 2012 the Asian Longhorn Beetle was spotted in Kent. A rapid eradication programme fortunately succeeded in removing them from our shores, but we must remain vigilant.

All walkers care deeply about the countryside. Nature connection is one of the main pleasures of walking. So, the next time you go for a walk somewhere new, do give your boots a quick wash first. Simply think of it as paying it forward to nature and following government guidance on biosecurity.


If you are interested in signing up to Observatree, email: observatree@woodlandtrust.org.uk

If you’ve enjoyed this post you may also like: A Woody Western Weald

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