| Advice on management of bleeding canker of horse chestnut
Confirming exactly what agents are causing horse chestnut bleeding canker is critical to any recommendations about effective control measures. Before embarking on any control measures on sites where there is a significant number of horse chestnuts, a survey to assess the number of affected trees is recommended.
There is no chemical treatment currently available to cure or arrest the development of bleeding canker:
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If the lesions become so extensive that the entire trunk is girdled, the tree will inevitably die and have to be removed and disposed of appropriately. |
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If major branches are infected and show dieback they should be removed, because recently-dead branches of horse chestnut may be susceptible to sudden fracture and drop as the wood dries out. |
Advice on the best time of year to prune is given in Arboriculture Note 117 (Lonsdale, 1993). However, many trees with trunk infections retain healthy-looking crowns and may not pose an immediate safety risk. Some may even survive for many years as disease progression can be very slow or even cease, and show signs of recovery as vigorous callus development occurs at the margins of wounds created when bark has been killed by the disease.
Detailed information
Specific recommendations
Surveying
Disposal of infected material
Replanting
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| NATIVE
OAKS SUSCEPTIBLE TO NEW TREE DISEASE
Two cases of a new pathogen that
could seriously affect trees have been found in native English
oak (Quercus robur) trees in a wood near Redruth in Cornwall.
This is the first discovery of fungal disease caused by this Phytophthora
species in native oak trees in Britain.
The pathogen, is related to Phytophthora ramorum, known in the
USA as Sudden Oak Death because of the widespread blight it has
caused on American oak species. However, until now, native British
oaks have proved to be resistant to both pathogens. Since the
first discovery of P. ramorum in Britain early in 2002, neither
laboratory tests nor painstaking surveys of more than 1500 woodland
and forest sites across Britain have established any susceptibility
of native oak trees to the deadly fungus.
Although P. ramorum is known to exist in more than a dozen countries
throughout Europe, the new Phytophthora is so far thought to be
specific to Britain. A major concern is that laboratory tests
and observations in the wild indicate that it is more aggressive,
and much faster spreading, than P. ramorum. Rhododendron, the
main host and source of infection, succumbs in just a few weeks,
rather than months.
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Diseased Oak |
This
latest discovery raises fears over the pathogen's potential impact
on Britain's 200 million oak trees, as well as other native tree
species that may now prove to be susceptible.
The
Forestry Commission's Head of Plant Health, Roddie Burgess, said:"Our
hope was that P. ramorum, and this more virulent pathogen, would
not spread to native species. This new evidence indicates that
this is not the case. We need to ensure that the precautions we
take to identify and control the spread of this disease are commensurate
with this significantly more serious threat.
If
anyone suspects the presence of the disease on plants they should
contact their local Defra or SEERAD office. If the disease is
suspected on trees the contact should be the Forestry Commission.
Further information on the two phytophthora is available on the
Forestry Commission and Defra websites -
http://www.forestry.gov.uk and http://www.defra.gov.uk. |
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