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.
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