Pests on Trees

Imported pests on trees 2012

Around this time last year, we wrote a piece on Horse Chestnut leaf miner (Cameraria ohridella) and how it had come to the UK and was spreading across the country.  From the spread of this, and Dutch Elm Disease in the 70’s, you would have hoped  we had learnt that the Channel will not protect our trees forever.  However, this is not the case with more tree pests and diseases being introduced.

These recent tree pests could be hugely significant on the trees that make up the English countryside over the next 10-20years. 

Oak Processionary Moth (Thaumetopoea processionea)

In 2006 Oak Processionary Moth was first found on a couple of sites in West London.  These caterpillars group together in numbers so large that they can completely de-foliate trees in a single season, at which point they process to the next Oak tree. They are covered in irritating hairs that contain a toxin  which, on contact with skin or when inhaled, can result in skin irritation and allergic reactions. Since 2006, the outbreak area has grown with outbreaks now  moving into East Surrey

Massaria disease (Splanchnonema platani)

Since 2009, there has been confirmation of Massaria disease on Plane trees in London.  Although individual cases had been reported previously, the frequency of occurrences in 2009 raised alarm. The disease is specific to Plane trees and will often lead to branch die-back and failure if adequate pruning work is not completed.

Asian Longhorn Beetle (Anoplophora glabripennis)

Early this year Asian Long Horn beetle, a native of China, was found in Kent and poses a serious threat to a wide range of broadleaved native trees. The larvae of the beetle live and feed in the tree, killing areas of the functioning timber and possibly leading to tree death or secondary infection.

Phytophthora ramorum

A fungus like pathogen was found a few years ago in the USA and at that time few trees were affected in the UK. However, in 2009 it made headlines in the UK when it was found to have affected many plants and shrubs but particularly rhododendron, viburnum and camellia. The pathogen’s behaviour changed resulting in it rapidly reproducing and infecting  commercially important conifer tree species. It has now spread to many parts of the country from the South West to the North.

Whilst all of this may sound rather negative, the Forestry Commission are working towards a more strategic approach to forest and tree health, and we can all do our bit to help prevent the spread of pests and diseases from site to site.

The Forestry Commission have offered the following advice to the public when enjoying the great outdoors.

Mud can carry pests and diseases, so always clean your boots and shoes, and wash down the tyres of bikes and vehicles after off-roading. Keep to obvious paths when walking in the countryside and keep an eye out for any information on notices.

Plants and leaves may already be home to pests and diseases and therefore avoid taking plants or cuttings home from forests. And that last piece of advice is to resist planting out your garden plants in the countryside or dumping garden waste.