Ivy
Latin name Hedera
Helix. Common Ivy, or English Ivy
as it is sometimes known as, is a climbing plant
that is equally at home climbing a wall or a tree. Ivy
in the US is an invader species and because of its aggressive nature is
rated in some states as a Class C noxious weed.
It
is my conviction that the
effect of ivy on trees is always negative; above
the
ground it causes shading and prevents air from reaching the bark of the
host tree,
underground
the roots severely limit the tree's access to the essential
resources of nutrients, moisture and
space and makes it more susceptible to
pests, disease and wind damage as well as causing poor foliage growth
and over time ivy will reduce the growth of the branches especially
the lower ones. Adjacent trees are also affected by shading and
the tendency of tree ivy roots to grow outwards from the affected tree.
The
coexistence of Ivy and trees is not a symbiotic one,
neither is ivy truly a parasite. The ivy
is, however an unwelcome burden in that it uses the structure of the
tree to achieve the height necessary to reach sunlight and it then
starts shading the host tree and adjacent trees of this resource and,
of course, depriving the tree of nutrients, moisture and root space.
Ivy
is a weight burden to the tree and it makes the tree more
vulnerable to storm damage as a result of the combination of weight and
increased cross sectional area. Most of the weight of the ivy is,
like
most living things, due to water and if it is also waterlogged by
rainfall,
just the water alone can weigh as much as three quarters of a ton.
With
the rapid onset of cimate change and other stress factors it is
increasingly important to
optimise the growing environment for native trees and this includes
removing ivy. Stunted
and damaged trees are obviously not as effective at
producing oxygen and sequestering carbon dioxide as a healthy one.
Volunteer ivy pullers are needed everywhere. Forests weakened by
rapidly increasing temperatures can more easily fall victim to
ivy's opportunistic nature.
When ivy is not controlled in woodland, it often becomes the dominant
ground cover plant, resulting in a
monoculture which someone described as a "Green Desert". Ivy smothers
seedlings
and displaces many of the
native species that are vital to a healthy woodland ecosystem.
It
is imperative to remove ivy from young trees and
mature trees
benefit as well. Ivy will, if sufficiently well established prevent
light reaching lower foliage of not only the host tree but nearby trees
and the forest floor.
Ivy damaged trees can recover to some extent if the ivy is killed off,
however, if the infestation started off when the tree was relatively
immature and has been present for many years they usually remain
misshapen and spindly, perhaps
for the rest if their lives. A tree that has been "liberated" from
Hedera will quite obviously have less growth in the lower branches, in extreme
cases this gives the tree a kind of cauliflower appearance.
Even
in the UK, where it is a native species it often
grows uncontrolled and can be a serious problem. Woodland in England
was,
until
recently almost always well managed and ivy prevented from overrunning.
Deer used to be present in woodland and their grazing would help to control its growth on the forest floor. In
groves where the trees are sparsely planted the ivy can receive enough
light to allow it to quickly cover the forest floor and oust all other
species, and then, in time, reach up to the upper branches. Ivy
is naturally excluded from the main body of ancient European forests,
but will invade and colonise secondary and more recent plantings.
So even in its source country it is often a problem, it
should always
be removed from trees such as the
Larch and Ash as their foliage allow light to reach the encroaching
vine,
speeding its ascent.
Could some new factors be making ivy more robust and
"thuggish". Climate change and newly introduced diseases are currently
decimating native
trees but are having less effect on ivy. Also, some of the imported
ivy cultivars could be hybridising with the local
variety, and there may be non-native species present in the UK as well.
Most ancient woodland in the UK does not experience a major problem
with ivy invasion and it tends to remain on the periphery.
In
the US and countries where ivy is not a native species
great care needs to be taken to prevent uncontrolled proliferation and
release, it should be prevented from reaching its mature form as it's seeds
can be spread by birds. Some varieties are very attractive and it is an
easy ground cover solution, but planting English or Irish Ivy can
result in enormous damage to local woodland and some forests may never
recover. Responsible people should eradicate it wherever it appears.
Why not get together with some friends and have an "Ivy
Pulling Party". You can all have some fun and see the forest becoming
beautiful again. It will be quite hard work and results will not be
obvious straight away, but it is such good exercise and it's beneficial
for your physical and mental health.
Caution:-Ivy is toxic to
humans, pets and domestic animals, and can cause dermatitis.
Killing ivy on trees.
Remember to use a good pair of gloves and wash thoroughly
after working
with ivy.
Obviously the unrelated
Poison Ivy is
very much more harmful than Common Ivy, but English Ivy sap is an also
irritant. Also use protective goggles, or
at a pinch glasses or sunglasses. The gloves will not only protect you
from the
toxic sap but you will be using sharp tools and the author has some
personal experience of saw scratches on bare limbs and similar
minor accidents.
Immediately
pulling the ivy away from the tree after the ivy has been cut off from
its roots is not recommended, as
the bark of the host tree could be damaged. The job of pulling off the
dead ivy vines,
if it is necessary, should be delayed for a year or two and
left to someone who can execute the removal without damaging the tree -
and other
humans (ivy can be very heavy).
A
popular approach is to cut the vines in a ring around the
tree, usually
around chest height and then again at the root level, or even below the
soil level. The disconnected
vine should be left for at least a good few months before attempting to
pull then off, a couple of years is even better. When some time has
elapsed the vines can then be very gently pulled off, great care being
taken to
ensure that the bark is not damaged. Also be careful about not
penetrating
the bark when cutting the vines, gently lifting the vine away from the
tree
with a screwdriver can allow a pruning saw or pruning shears to be
used. More at this link- https://www.gardeningknowhow.com/ornamental/groundcover/english-ivy/english-ivy-tree-damage.htm
Caution:- English Ivy is toxic to
humans, pets
and domestic animals, and can cause
dermatitis. Wear gloves and cover exposed skin, wear a mask if raising
dust when cutting or removing it.