what is the cause of this?

[simonm]

What is causing this on a Horse Chestnut? i have seen the same thing lots of times but don't know what it is

[Ian C]

Looks like Later stages of HCBC.

[treeseer]

A spiraling wound, with response growth not looking that strong. You can find out more by excavating soil under the wound to check root condition, and by pulling back dead bark to assess condition around the margins.

 

Lightning often causes spiral wounds. Root damage is also a possibility. not sure a bacterial canker would cause that kind of wound, but i am not an HCBC expert.

[David Humphries]

it may be symptomatic of HCBC but don't rule out other pathogens involved.

 

We had a mature HC with historical bleeding canker that declined fairly rapidly, but was also subject to Armillaria.

 

If you get a chance to do as Guy suggests, whilst having a dig around at the base of the dysfunction keep an eye out for rhizomorphs.

 

.

[treeseer]

Ooooo that last pic is gorgeous!