Bleeding Canker
of Horse Chestnut
The telltale signs of bleeding
canker on the trunk of a horse
chestnut tree.
Photo credit:
Forestry Commission. IT HAS England’s least light polluted skies, its most remote village, and rates as one of the most tranquil spots imaginable. But when it comes to wildlife, Kielder Water and Forest Park, Northumberland, is like ‘Piccadilly Circus’!
THE Forestry Commission has
published the results of a survey
that indicates the extent of
symptoms of bleeding canker of
horse chestnut trees throughout
Great Britain.
A condition that has been
affecting increasing numbers of
horse chestnut trees in recent
years, bleeding cankers are lesions
that ooze or ‘bleed’ liquid from the
trunks or branches of trees.
In the case of horse chestnut,
some trees eventually die, some
recover, and others have to be
felled for safety reasons because
the condition weakens the trunks
or branches until they are in
danger of falling.
For several decades, small
numbers of horse chestnut trees
have been known to suffer from
bleeding cankers caused by one
or the other of the fungus-like
organisms Phytophthora
citricola or Phytophthora
cactorum. Infection rates stayed
at a low level and therefore did
not cause concern.
However, a few years ago the
Forestry Commission detected a
steep increase in the number of
reports of bleeding canker. In the
vast majority of cases analysed
since then, scientists at the
Commission's Forest Research
agency have not found
Phytophthora organisms to be the
causal agent.
Instead, it gradually became
clear that in many samples taken
from the affected trees another
organism, eventually identified as
the bacterium Pseudomonas
syringae pathovar aesculi, was
causing the canker symptoms.
Responding to the concerns of
the public and tree owners, and
those of woodland managers
worried that the infection might
spread to other species, the
Commission conducted two
research projects during 2007.
The first gathered information
from landowners, land managers,
local authorities and tree-related
organisations to ascertain the
approximate extent and location
of horse chestnut trees across
Great Britain. Then, informed by
this data, the Commission
inspected sample groups of horse
chestnut trees in all regions of
Britain to estimate the incidence
and distribution of symptoms of
bleeding canker.
It was learned that trees with
symptoms of bleeding canker
were found in all 11 regions; an
average of 49 per cent of the trees
inspected displayed symptoms
that indicate or might indicate
bleeding canker and there were
regional variations, more affected
trees being found in the southeast,
although no region had less
than 30 per cent.
Region is turning over a
new leaf, says report
The report reveals good progress in
protecting the endangered red squirrel.
Credit Mark Pinder MAJOR progress has been made in protecting
some of North East England’s most threatened
wildlife and habitats and the future is bright
for wood production. But more needs to be done to green the
region’s urban spaces.
These are just some of the conclusions of a
report published recently charting progress in
implementing the North East’s Regional Forest
Strategy, which was launched in 2005.
The document says that 60 key projects have
been completed over the past two years and a
further 100 are either planned or on-going.
Significant advances have been made in
conserving red squirrels where an alliance of
organisations, backed by grants from Defra and £626,000 from the Heritage Lottery Fund, are
bidding to stem the tide of grey squirrels. Key habitats are also recovering.
Over 375 acres of the Border Mires in
Northumberland, England’s biggest upland
bog, have been restored by removing conifers
and blocking drainage channels.
And there are also the green shoots of
recovery for vulnerable ancient woodlands,
which date back at least 400 years. Improving
their condition remains a top priority after a
survey revealed that over half of those in
Northumberland were in a poor condition.
However, more restoration schemes are
planned and further condition surveys are
now needed elsewhere in the region.
Richard Powof the Forestry Commission said: “Overall the picture is pretty encouraging and
an impressive range of projects are under way
to ensure we maximise the benefits from our
trees and woodlands. This report shows just
how much has already been achieved, but it
lays down markers whereweneed to do better.”
The document also signals an expansion in
the wood-fuel sector in the North East. Britain’s
biggest biomass power station opened at
Wilton-on-Teesside in 2007 and Northwoods,
which delivers training and business support,
is looking to strengthen biomass supply
chains. Egger UK at Hexham have made a £100-
million investment – one of the biggest ever
investments in manufacturing in the North East – which has maintained the global
competitiveness of this chip-board factory.
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