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London’s Plane Trees Under Threat

London’s plane trees could be under threat, warns the London Tree Officers Association (LTOA), from a new disease originating from the Continent.

Plane trees account for 10% of all trees in London, making them one of the most densely populated breeds in the capital. With origins in Britain dating back to 1550, many of the current plane trees are about 300 years old, with many having survived in London for so many years due to its restorative nature. Shedding its bark regularly, the trees are able to capture and rid themselves of any airborne pollutants. This makes it one of the most resistant breeds for city landscapes, also playing an important role in improving urban air quality.

However, plane trees could now be under threat due to the arrival of canker stain from the Continent. A newly published statement from LTOA describes the fungal disease, Ceratocystis platani, as a “true killer, impacting on a par with Dutch elm disease upon the elm population.”

This is a major worry to the arboriculture of our cities if canker stain is to arrive on our shores. The living cells of the wood in the phloem, cambium and sapwood are invaded incredibly quickly once a fresh wound exposes those cells.

Infected plane trees can be identified by their sparse foliage, small leaves and elongated sunken cankers on the trunk and branches. The fungus is less likely to occur during December and January, but we should be concerned for the spring months, as the infection can typically be spread from tree to tree via pruning.

Like Dutch Elm disease, canker stain of plane is a vascular wilt, and will prevent the flow of water and nutrients to the leaves, meaning the result can be fatal. Although already well recognised in southern and central Europe, it was not believed to be present in the UK, yet last year a ‘concern’ was raised by the Government’s Food & Environment Research Agency (FERA).

The LTOA is supporting a ban on importing plane trees in the hope of deterring the disease, but this has to be agreed to by Defra who must first be convinced it is not already in the country. The Forestry Commission is working with them to discover this.

Discussing the subject, agb Environmental’s Principal Arboriculture Consultant, Richard Parmee, said: “This is yet another disease that has been accidently imported into Europe and is now threatening trees in the UK. Halting imports of Plane trees from infected areas and being alert to the symptoms are the best means of preventing it gaining a foothold here.

“Our surveyors will be on the lookout for this disease when undertaking tree surveys of London Plane. If we do identify it, we will be very happy to discuss management option with the tree owner.”

For more information about any problems concerning diseases for plants and trees, contact Alex Brearley on 01638 663226 or email alex@agbenvironmental.co.uk.

Arboriculture, Show All