[NAFEX] Bark Damage

Heron Breen breen at fedcoseeds.com
Mon Dec 5 16:27:02 EST 2005


Hi,
Here are some best practice methods to deal with girdling.

Not are girds are down to the actual xylem, ie through the cambium, or even the
phloem. The inner bark as is commonly known is actual the phloem, and this is the
tastiest parts that rodentia etc like best. If the cambium remains intact, which
easily can, it will draw sugars from parenchyma cells inside the xylem (wood) and
rebuild the phloem pathways that have been destroyed. Phloem "flows down" is a
key phrase to remember with tree physiology. Some species of trees can survive
phloem damage, some cannot. Malus does okay, while Prunus are more dicey,
depending on all the factors touched on below. Applying a clay slurry to the
affected areas within 24-48 hours of damage will keep the cambium from
"sun-damage". Apply repeatedly over the course of a month on the opened areas as
rain washes it off, or as heat cracks it. We're not talking glop, more of a thick
basting.
Scribing is way of cleaning up a wound site so that even cambial growth will not
cause more bark splitting or decay and to reduce "ram's-horns" which are thick
growths of in-curved cambium. Ram's-horns are not bad persay but one should try
scribing if they feel confident they know what they are doing. Since a google
search will probably result in a pictorial description, interested parties should
see before doing. Scibing can help reduce suckering from the sides and bottom of
the wound, which is the worst case scenario. If suckers result, you will be in a
no-win battle with the tree's metabolism. If it is a young tree, you would
probably do best to remove and replace it. Older tree, do not cut the suckers
back for at least three years. Many of them will die on their own. Let them get
woody and then do not flush cut. Cutting suckers back every year gets old and
just encourages more. You may have to live with some.
Do not fertilize the tree at any point until the wound has been dealt with by the
tree, say another year. Fertilization next spring would be one of the worse
actions to take. The tree will, if as you report the tree has remaining intact
phloem and cambium, most likely survive. You may get a better risk assessment if
you would report what percentage of the tree's perimeter, and how high up and
width iseach tree is girded. The trees, if they survive the freezing and cracking
of winter, will compartmentalize the wound, and are probably doing just that as
we speak. This means creating internal barriers against infection and future
defect. The exposed wood make look cracked by next spring, but do not use this to
surmise the tree is mortally wounded. 
What counts a lot is in what state was the tree when it was injured. Was it
well-rooted, with adequate (and not too much) moisture? Lots of competition from
sod? Over-fertilized? On a dwarfing (read strangling) rootstock? Keep all of its
leave area for the whole season? Not just recieve vigorous pruning? The only
reason at this point that I would be concerned is that your tree was injured in
the Fall, the time of year when a tree has the least ability to compartmentalize
the wound. Normally, all sugars and waters stored would be sucked out of the
xylem layers already present and used to push growth and healing next spring. All
this before the barrier is laid down completely. Your tree will close off all
those years of layers forever, most likely, and be reliant on the vascular
structure it newly forms next year. This is why drought is deadly, or excess
growth, and why symptoms of drought can be evident even when it is a perfectly
lush spring/summer. The vascular structure has recieved a major set-back, and
your tree will have to struggle to compensate. 
Bridging the damaged area with grafts next spring may be another option, adding
vertical vascular pathways. But if the tree has adequate cambium remaining and
not too much perimeter to cover, it may be best to leave the area un-grafted.
This type of descision can only be made by visual observation, and even then is
somewhat of a 6 of one, half-dozen of the other, depending on the wound. 
Not that any of this info ensures the survival of your tree, but some may help
you not be the reason for its death, rather than the animal and other damage.
If your trees survive it will take 3-4 years before the vascular system is
balanced, or it may be forever trying to compensate for abrupt dynamic swings.
Some of this depends on cultivar, weather, future damage, the tree owner, and
luck or its opposite:fate.
Good Luck,
Heron Breen
zone 4, Maine  






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