Archive for the ‘ Horse Chestnuts ’ Category

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What’s happening to our conker trees? The dying out of the horsechestnuts..


Has anyone noticed that all our conker trees are dying?  They are brown and crispy and aren’t producing the fat juicy conkers they used to when we were children.  A blight on the scale of Dutch Elm disease (responsible for annihilating the elm population of the UK in the 70s), has been devastating our horsechestnuts over the last few years.   And no-one seems to have a cure for it.   Will our future generations have to go without conkers and not benefit from the beauty of these majestic trees?

What’s happening is the trees are under threat from a lethal combination of pests, diseases and unfavourable climatic conditions attacking them simultaneously.  The leaf miner moth (Cameraria ohridella) and the fungus (Guignardia aesculi).  Not to mention the effects of drought.  And now there is another, greater threat to these stately trees – namely Bleeding Canker.

The first symptom is often an area of bark where a yellow / brown / red liquid seeps out. In the spring, this coloured fluid is usually transparent but in warmer weather it may become cloudy. When it is dry and hot, the flow may dry up – leaving a dark crust on the bark. However, the bleeding may start up again in the autumn. These observations have lead to the suggestion that the pathogen is most active when conditions are mild and moist (i.e. in spring and autumn).

Where the pathogen has been active, bark, cambial tissue and the phloem (the sugar conducting tissue) are destroyed. If this damage spreads around the trunk then more general effects will be seen, namely yellowing of the leaves, early leaf fall, failure to set fruit (no conkers!) and damage to the crown of the tree; branches may be weakened and fall.

Dr Jean Webber, the Principal Pathologist at Forest Research, the scientific arm of the Forestry Commission, said that bleeding canker has been spreading quickly across Britain since 2001, having been confined to the south of England since the 1960s.

She said Forest Research believes its increased prevalence has been caused by a newly detected Indian-born bacterium, Pseudomonas syringae pv aesculi, replacing Phytophthora, a plant-destroying fungus, as its main cause. This may have been aided by mild winters and wet springs in recent years.

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Dr Webber said: “There’s nothing much you can do about it if your tree displays the symptoms. Our advice is: if you can do, leave the trees well alone, unless they become so damaged that they create a safety hazard.  “Disturbing the trees, by pruning them or making other attempts to clear the infection, may result in the bacteria being spread even further.”

It’s both sad and surprising how little publicity there has been about the plight of the horse chestnuts.  I hope something can be done so future generations get to enjoy these majestic trees and their beautiful conkers.  Once you become aware of it – you’ll be surprised at how many horse chestnuts there are in the UK – most British villages and parks would have a significantly different  look and feel if we imagine a world without them.