oldclaypaws wrote:Or.... another possible culprit, Chestnut blight (Cryphonectria parasitica). Just to add to the confusion, the symptoms do look a bit like squirrel damage....
Certainly chestnut blight is lurking just across the channel - and could at any time become the next big problem - We need the government to take steps about this now before a problem arises. It has been found in the uk this year - but it looks like control measures have been successful. At least if chestnut blight does arrive there is a method of biological control that can reduce the severity of its impact.
The pictures posted by Woodmonkey do not indicate Chestnut blight as a likely cause. To the experienced eye the symptoms do Not look like squirrel damage. In the picture posted by OCP the infected area has been extended with a sharp cutting tool (look at the top of the damage area - you can clearly see where the healthy outer bark has been cut away) to demonstrate the change in colour of the sap wood at the front of the spreading infection. This isn't how Chestnut blight lesions look naturally - this has been modified to demonstrate an aid to recognition.