Horse chestnut canker

Bleeding/Horse Chestnut Canker affects Horse chestnut (Aesculus hippocastanum) of all ages but younger trees are more susceptible. The disease was first reported in the 1970s but up until recent years has been fairly uncommon. Cases rose from four being reported in the year 2000 to over 110 in the year 2006.


Linked to the bacterial pathogen Pseudomonas syringae pv. aesculi and occasionally can be caused by Phytophthora

Mild winters and wetter springs may caused the symptoms to worsen recently


Bleeding areas on the stem or branches, often a reddish/brown or even black colour.

The area where bleeding has oocured may crack and fungi may appear on the surface or appear to grow from the cracks.

If a tree has multiple bleeds the crown will appear to have yellow foliage and lose its leaves prematurely. Some parts of the crown will fail to flush at all.

Leaves may also appear to be smaller, thinner and wilt in chronic cases.

The inner bark under the bleeding patches will usually be dead with an orangy/brown mottled effect.

At present there is no chemical treatment for Pseudomonas syringae pv. aesculi to either suppress or eradicate the disease. Confirming the case is crucial to getting the right measures in place early.

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