Cheshire West and Chester Council have provided CPRA with the following guidance regarding the problems affecting horse chestnut trees:
At present there are a number of different diseases and infestations which are causing problems to our native Horse chestnut trees, Firstly a fungal infection known as Phytophthora ( Bleeding Canker) was first spotted in the 1970’s and caused stem bleeding; although this was quite rare. More recently the incidence of bleeding cankers has increased dramatically and it is now believed a new agent is causing the majority of the damage, this is a bacterial infection by Psuedomonas syringae pvaesculi. This disease is initially spotted by bleeding sap (often causing a rust coloured stain on the stem and scaffold branches) and as the disease progresses early discolouration of leaves and defoliation of the affected tree. Eventually the cambium (living tissue under the bark) around the bleeding wound becomes necrotic and dies which can lead to the effective internal ring barking of the tree and its subsequent death. At present there is no definitive treatment to cure the infection and sanitation felling has not proved to be an effective control although some trees appear to recover from even bad infections so felling is only carried out where there is a significant safety issue. We have recently decided that 2 small horse chestnuts around the junction of Curzon Park North and South have reached the point at which they should be removed, these trees will be replaced with a suitable heavy standard sized tree of either native small leaved lime (Tilia cordata) or of a Beech variety.
Unfortunately at present there are a number of other agents causing problems one of these is Horse chestnut leaf miner (Cameraria ohridella). The leaf miner is caused by a moth from Europe that was first found in the South East in 2002 and has slowly migrated northward. The moth lays its eggs on the leaf into which the larvae create mines. The leaves eventually turn brown. Evidence suggests that while defoliation of the trees occurs earlier than usual it occurs late enough in the growing season that it does not appear to cause a decline in the leaf flush the following year. This mainly causes a visual problem but doesn’t appear to harm the long term health of the tree. It is likely that once established the moth will continue to cause the problem year after year and is able to survive harsh winters. Removal of fallen leaves in autumn may help to halt/minimise the number of pupae that can over winter and the leaves should be destroyed by commercial composting or burning. In the long term it is hoped a biological control may be found.
Further information on the above can be found through the following links www.forestresearch.gov.uk/fr/INFD-6KYBGV
Sadly, there is apparently no cure for damage done to the roots of a wide variety of trees by honey fungus (pictured below). Where trees that are affected by it, there will be
substantial growth of the fungus evident at the base of the trunk, particularly in late summer/autumn. The tree itself may otherwise appear perfectly healthy above ground, but its roots are being eaten away. Eventually – maybe after many years, maybe not – the roots will have been weakened to the point of being unable to support the tree, and it will topple without warning. THIS HAS HAPPENED TO SEVERAL TREES ON PRIVATE PROPERTY IN CURZON PARK IN RECENT YEARS, fortunately without serious damage or personal injury, so far. Symptoms must, however, be taken very seriously.