Hi Klara,

On Sun, 14 Oct 2007 16:47:38 +0100
Klara wrote:

Emery Davis writes
Klara, if the stripped bark rings the tree so that the cambium is
broken, everything above that point will die. You might as well cut it
back now, and start pruning for basic shape next year. This is better
than starting again because your maple is already somewhat established,
which is the hard part. If 90 degrees or more of cambium remains at
any place my experience is that the tree might recover. Use a sharp
pruning knife to clean up the wounds, and then _do not_ at all costs
treat or fertilize. Do your best to keep the area dry. The only
reason to start over will be if the damage is below the original graft,
in which case you have just the root stock. (Which will be nice but
will also grow into a large tree!)

Thanks, Emery. I tried to find 90 degrees' worth of bark, but I doubt
there is that much there - and I'm pretty sure the crown is dying. I
can't work out what caused the bark to split ... I thought it might be
an animal, but if there is some illness that might have that effect,
then that looks more likely. Could all the rain this summer have
affected it?


Is there any blackening around the area? I've had sections of cambium
die (on a SK too, I've got 4!) from pseudomonas, a local fungal infection.
At least I think so, it's really hard to tell without a lab analysis. Anyway this
summers wet weather arranged nothing, all my maples hated it.

That leaves us with 65cm of trunk (from what was about 1m, and then lots
of shoots below that level going right down to the ground - as if the
tree is trying to make up for the crown dying. I don't know where the
graft is - the shoots below that point all look the same at this stage
as those in the crown, and I don't know enough to know where I should be
looking. What rootstock would the sango kaku have been grafted on?


The rootstock will be green or gray depending on age and circumference. It is
just seed grown Acer palmatum, and might have any characteristics beyond
being vigorous. The species is extremely polymorphic. But it's almost certainly
only a few centimeters above ground on an SK. If the majority of the stem is
reddish, it is above the graft.

We would really like to keep what is left, for its sentimental value if
not anything else. There is just a little damage to the bark below 65cm
presumably we leave that alone?


Yes, that's right. Just left it heal naturally. Keeping dry is the most important
thing, and that the roots are well drained of course.

Is it essential to cut the trunk now? (It's just really painful to do
that, and what if I'm wrong and it would recover?)

If we do cut it, presumably at an angle away from the top healthy shoot,
do we paint anything on the cut? Do we cut it now or when it's dormant?
Being a maple, will it react like a Vermont maple and lose its sap?


Cut 2 inches above a healthy bud pair, it will die back to the buds. Don't paint.
The angle of the cut isn't important.

You are right to worry about bleeding, but since there is already reduced sap
flow to the top of the tree it will not be too much. But japanese maples can
bleed profusely if you get them at the wrong time.

I guess on balance (and without seeing it) I'd wait for dormancy to prune, so
long as there is no blackening above the injury. If you notice any dark
streaks above the damage, prune immediately and don't forget to sterilize
your secateurs afterwards.

Finally, what shape can we aim for, being left now with a 65-cm trunk
and shoots going all the way down? (So sad, for three years we had such
a healthy, lovely little tree....)


It will probably put out long shoots, 2 feet or more, next spring. You can certainly
use one of these as a new central leader, or go for a vase shaped look.

The following thread contains lots of discussion about pruning of these trees,
from the UBC maple forum:

http://www.ubcbotanicalgarden.org/fo...ad.php?t=22077

Personally I agree with Mr. Harris, that in our climate anyway autumn is fine,
spring is OK but it must be very early otherwise you seriously risk weakening the
plant.

I try to be pretty minimalist with the interventions. Another of my SKs was badly
infected with verticillium wilt this year -- thanks to the never ending wet -- and I
had to lop from about 5 feet to 3. It grew out very bushy, looks odd but not unattractive!
I may do a little shaping this winter.

Sorry about all the questions, but we know very little about trees and
nothing at all about Japanese maples....


As you may note from the link there is a lot of conflicting advice, there are only a
few maple experts and even they don't all agree. About anything!

-E
--
Emery Davis
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