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Girdling is a killer
When rabbits and voles (meadow mice) gnaw on tree trunks and
shrub canes during winter, those parts of the plant may die right
away -- simply not leaf out.
If the damage is extensive without completely circling a stem,
the leaves may grow only to wilt suddenly and die a few weeks later
or during the first hot spell of summer. That's because the
critters' gnawing stripped away the cambium, breaking the path
starch (energy) must take to flow from leaf to root. Sans cambium
the foliage can grow, because it uses water coming up through the
woody xylem of the canes. However, those leaves cannot repay the
favor by nourishing the roots. So the roots starve, then foliage
and wood die, too.
Strategy for controlling animal damage
This viburnum (below, left) has been stripped of
cambium. We'll cut the canes back (for the second year in a row) to
see if the plant has the energy for yet another comeback. (To see
rabbit chewed burning bush cut back, see Remedy rabbit
Our strategy in this garden has been capitulation plus removal
of target plants and replanting with non-food species. All other
options -- animal trapping, fencing and the use of repellents --
have been vetoed by the owners. Per that strategy, since this
viburnum can't provide us with flowers when it's cut back annually,
we'll dig it out and plant an unpalatable substitute, such as
elderberry (Sambucus nigra).
Nearby (above right), rabbits nipped off all this
weigela's canes, except one. We could leave that branch to bloom
but it would only look silly. We'll cut it back to the ground to
match the others, and accept just one late-season bloom from this
plant. Too bad, since without rabbits we normally manage weigela to
bloom twice per year.
Voles -- also called meadow mice -- tend to do their damage at
the very base of a trunk, or even just below the soil line where
roots meet trunk. They're as effective as rabbits at girdling a
plant but because the damage they do can be more easily overlooked,
the plant's death may seem more mysterious. (Control measures for
voles in Growing
Right: Only when we cleared mulch and soil away from the
tree's trunk could we see the bark had been gnawed by
Far right: Rabbit chewing is usually much easier to
Specialized grafting called bridge grafting can reconnect the
cambium above and below girdling damage. For a very special tree it
may be worth looking into, but don't expect to hire it done. (See
Deer tend to browse higher than rabbits although both critters
may favor the same plants.
Above, left: The base of this hedge is bare from deer
Above, right: Gardeners should learn to recognize animal
damage in early stages, and exclude or repel the culprits. Do you
see where browsing has begun on this arborvitae?
Below: Yes, there's the deer sign.
Below, left: Deer have an overbite so the stems they feed on
tend to have one ragged edge. Below, right: By comparison, rabbits
make very clean cuts.
Other signs distinguish between garden-raiding critters, such as
deer's triangular hoof prints and deer droppings. (a.k.a. manure, dung,
These arbs (right, arborvitae or eastern cedars,
Thuja occidentalis) have not discolored from winter cold,
by the way. It's normal for this variety for the most exposed
foliage to become bronze as its internal chemistry changes to
protect cell fluids from freezing. It will become green again as
the weather warms and days lengthen.
Focus, not flowers!
We sometimes miss animal damage because we're starved for color
and distracted by flowers in spring. For instance, we almost missed
the new chewing on this spring witchhazel (Hamamelis x
mollis 'Arnold Promise').
We watch for patterns in animal damage, to help prevent
recurrence. These two spicebushes (below, Lindera benzoin,
a yellow flowered, spring blooming native) were the same size last
year. Look carefully. (We know; it is hard to see bare canes
against mulch in spring!) See how much more of the far spicebush
has been eaten?
Notice, too, that it's the spicebush closest to the junipers
that's been most heavily browsed. Rabbits are skittish creatures
that stick close to cover. A fence with very small openings along
the edge of the junipers may do as much to protect the spicebushes
as caging around each bush. Use rabbit hutch wire, or hardware
cloth; rabbits can squeeze through chicken wire opening.
So look down for scrapes, rabbit- or deer dung, and hoof prints
as you assess the winter's toll. We know a specimen such as this
weeping white pine (at right, Pinus strobus 'Pendula') may
be your special love and so you worry about its unusually pale
foliage. Still, try to look over everything. If you lose those
shrubs in the background (below), it may ruin your view of
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