"kay" wrote in message
...

A snake bark maple (sorry, not sure which species, but if it's important
I can dive into my reference books and find out) has an area of dead
bark extending about half way around the tree and for a vertical
distance of about a foot.

The tree is about 10 years old, trunk diameter about 4 inches (girth
about 12inches), height about 12ft. It's in cold clay, gets waterlogged
for a few hours at a time about half a dozen times a year, and is
surrounded by various other small trees and large bushes. Until now,
it's been growing healthily, and has flowered profusely for the last
three years.

There is no sign of pest on the dead bark area, or any sign of weeping,
visible fungus or anything else. It looks like the sort of damage you
get when a couple of branches rub together, though this is obviously not
the case here. One twiglet growing from the damaged area is dead, but
the rest of the tree, both above and below the damaged area, seems
fine.

Any ideas? I've googled but not found anything - most acer disease hits
refer specifically to A palmatum, and adding 'snake bark' gets the sales
hits.

Can you lift up any of the bark to see if there is anything underneath
(animal or fungal)? How long has it been showing this damage? If the
damaged area moved all the way round the trunk and is not just superficial,
then could it ringbark the tree and kill everything above it?

If there is a dead twig growing out of the damaged area is it cause or
effect?

Sorry - more questions than answers. If you are a member of the RHS they
can identify pests and diseases if you send them a piece of the damaged
material
(http://www.rhs.org.uk/Gardening/Help...n-and-examina).

--

Jeff