It may look like a shallow scrape but losing the bark
can be deadly to shrub or tree
Dear Janet & Steven,
I read what you wrote a few weeks ago about rabbits
during the winter stripping the layer of bark from the trunks of
bushes. What you suggested was cutting back to below the eaten bark
but I need greater clarification before doing that.
The bushes are surrounding our deck, are at least 20
years old and about eight feet tall. It looks like the rabbits only
took the outside layer. All the gray bark is gone and it is white
for about eight inches around the main trunk. Below that it is only
about 20 inches to the ground.
That would be such a major cut back, would we risk
killing the shrubs? Is there something else we can do for the
wounds without cutting back? - J.V. -
Dear J.V.,
It my seem like "only the bark" but it's death to a woody limb
once the bark is peeled away.
We would cut the shrubs back to a couple of inches from the
ground and wait a few weeks before shopping for new plants.
Sometimes well established shrubs and trees can produce five or six
feet of new sucker growth in a year -- more coverage than you might
get from new plants.
However, if the tops of the shrubs have already leafed out --
however thinly -- you may see no suckering or only very little
growth if you cut the shrubs back now. That would be because the
roots have given up all their stored energy in the first flush of
growth but haven't received any or much energy in return. They may
have nothing left to give and the plants will die. More on this
exchange between the plant's top and bottom shortly.
The only alternative to cut back or replacement involves a skill
which is not available for hire and it's a stretch to think you can
learn in time to do it yourself.
To consider this alternative, you must first understand how wood
functions. Think of in layers, like a human leg covered in a nylon
stocking and then again in tough denim. The wood is the bare leg.
The nylon is a thin zone where new cells are made, called the
cambium. The denim is the bark, a very efficient protective
layer.
Water and nutrients flow through the wood from the roots to the
leaves. It's a one-way street, however, going up. Anything coming
down from leaves to roots must travel in the nylon -- the
cambium.
Although new bark cells and wood cells are made in the cambium
the "stocking" itself never thickens. It's an ever-thin, vital
layer.
The cambium is starchy since an important item it carries down
to the roots is starch, which plant cells rely on for energy. The
leaves can make starch through photosynthesis. The roots can't make
it and so depend on the leaves via that cambium conduit.
When rabbits and other hungry animals strip the bark they're
really out to eat the starch-rich cambium. The cambium may linger
if the bark is peeled away in a simple scraping by car or deer
antler, or when the attacking animal is a well fed but bored
squirrel. Left exposed, the cambium dies over time. It needs the
protection of bark to bear cold, heat, drought, and to thwart
attack by fungus or insects.
If the cambium is interrupted clear around a limb or cut in
enough places that it separates like a nylon with many runs and
holes, the roots are cut off from the leaves. They use up much or
all of their stored energy to send water up to the leaves to begin
the season, then wait for the leaves to reciprocate by sending
food. Cut off from that food, the roots die of starvation.
Then the leaves die, too, as water can't be taken up by dead
roots. Many people who didn't notice stripped bark are shocked by
plants dying suddenly during summer.
A technique called bridge grafting takes twigs from the
undamaged part of the plant and slips their carefully cut ends
under the bark above and below the damage, twigs' cambium pressed
firmly to trunk cambium. If the grafts "take" then starch is
permanently rerouted across the damage through the twigs, which
grow in diameter.
We've read about bridge-grafting in textbooks, have heard of it
used to save priceless plants at botanical gardens, and tried it
twice. We have our fingers crossed that our most current attempt at
it will save Janet's sister's squirrel-damaged Japanese maple, but
we don't know anyone who hires out to do grafting in the
landscape.
If you work quickly you might try it -- it must be done during
early spring. Now that you know the term, you can call up a diagram
on the internet or read from a tree care textbook to try it
yourself.
If you find a tree surgeon with the necessary skills you may
find the cost is high for such a specialized skill with uncertain
outcome. Replacing the shrubs may be inexpensive in comparison.
Short report
If you seek a pleasing plant, look around
you.
There are excellent garden centers everywhere. Go there first
when you're looking for particular plants. Write down the
scientific names of the plants you want, then use the phone book or
the internet. Show your list to the garden center staff or spell it
out to them over the phone. Don't start at department stores that
sell but don't specialize in garden plants.
Green thumbs up
to those who regard every new planting as a proposal to the
plant. They pick what seems the best place but check back regularly
to see what the plant "says." If it's not thriving, they change
their care or move the plant.
Green thumbs down
to frustrated but silent shoppers. Great garden centers become
great because the owners and growers are responsive to requests.
Ask for what you're seeking. Even if the answer is "sorry," that
plant is likely to be considered in future stocking decisions.
Originally published 5/15/04