Even outside established woodlands, Essex is home to some 90,000 oak trees across the countryside. But all of these ancient oaks face a new threat

It seems that we are surprisingly ignorant about our common trees. From a recent UK-wide survey, 83% of adults questioned couldn’t identify an ash tree leaf, 69% a leaf from a horse chestnut and (surprisingly) only 57% could identify an oak tree leaf. Logic would follow that it seems likely that four out of ten adults in Essex can’t even identify England’s iconic oak trees!

But does it matter? We could all go through life not knowing our ash from our elder. However, with 15 species of British trees presently being attacked by diseases, the Woodland Trust argues that if more people could identify common trees, tracking outbreaks and the spread of diseases would become easier.

Our early ancestors wouldn’t have believed that their descendants couldn’t identify common trees. Struggling to survive in an environment dominated by dense, hostile forest, relics of what we now call The Wildwood that once covered some 75% of Britain, they believed in the existence of numerous gods and other supernatural beings. Individual trees and woods were venerated as places where they dwelt in supernatural form. Some trees were thought to be inhabited by kindly spirits and others by mischievous or cruel ones. Early marriages were held under trees and many trees were venerated for their real or fancied medicinal powers. Our ancestors particularly worshipped oak trees in the belief that it was the first tree created. One of the oldest means of divination was to interpret the voice of the supreme deity through the rustling of its branches.

Druids gave great importance to trees. The word ‘druid’ is derived from the ancient Celtic words for oak and truth – ‘dru’ and ‘druidh’. They particularly venerated oak trees, wearing oak leaves round their heads as they honoured the regal power of the tree. One legacy of this is in the Leafman – a symbol of rebirth, representing the cycle of growth each spring. Leafman’s face, covered with oak leaves, appears today in churches, pub names and door knockers.

In plant lore, the oak is considered to be a symbol of courage, independence, faith, stability, honour and longevity. It represents all that is true, wholesome and noble. Druids believed that acorns represented good luck and long life. Even today, some people believe that an acorn placed on a windowsill will protect them from lightning. Look out for window blind pulls in DIY shops and often you will find that some of them are in the form of an acorn – another legacy of The Wildwood.

However, our venerated oak trees are being threatened by a disease which has probably been in the UK for at least 100 years, but during the last 25 years has become more active. Called Acute Oak Decline (AOD) it has attacked thousands of trees across East Anglia, the Midlands as far west as Somerset and it is spreading north. Dark fluid oozing from splits in the bark of 50 year old plus, and occasionally younger, trees are signs of the disease which can kill trees in five years.

Dr Sandra Denham, senior pathologist at the Forestry Commission’s Research Centre, described AOD as a secondary disease that takes hold when a tree’s defences are lowered due to stress. Although a small, native beetle and several species of bacteria are known to be involved, the mechanism of the disease is not yet fully understood.

Some 30% of the 15,500 hectares of broadleaved woodlands in Essex are stocked with oak trees and nearly 90% of these are more than 50 years old. There are also some 90,000 oaks over 15 metres tall scattered around the Essex countryside. Could AOD have the same effect on our oak trees as Dutch elm disease did on our elm trees in the 1970s? Are the 10,000 ancient oak trees in Epping Forest at risk?

The short answer is that nobody knows, at present, but sightings of affected trees have been increasing annually all over Essex since 2006.

Mark Iley, biodiversity coordinator at the Essex Wildlife Trust, has explained that the trust is aware of outbreaks of AOD on trust reserves around Colchester and Danbury, and believes there are more. Importantly, he also thinks that members of the public can help to monitor the severity and spread of the infection.

Essex Wildlife Trust welcomes reports of sightings of affected oak trees. Ideally they like to have a six or eight figure OS grid reference, a location (eg street or village name), the date it was observed and the name of the person who discovered it. A note of how many affected trees have been identified and the severity of the symptoms (ideally a photograph) is particularly helpful too. The information can be emailed to records@essexwt.org.uk.

So you can really help the battle against AOD. If, of course, you know what an oak tree looks like.