Gauteng Smallholder Gauteng Smallholder November 2011 | Page 37

IN THE ORCHARD
From page 33
biological weathering,
because mycobionts can
break down rocks and release
minerals by producing certain
chemicals. This is an essential
step for the formation of
primitive soils.
In some countries lichen
provides forage for certain
animals.
Lichens are also very useful in
monitoring pollution. They
absorb pollutants such as
heavy metals, carbon and
sulphur into their thalli.
Scientists then extract these
pollutants in order to assess
the levels present in the
atmosphere.
Fruit trees are no strangers to
bouts of fungus and lichens
growing on the trunk, foliage
and branches. However,
lichens are not parasitic and
won't harm the tree. Lichens
grow on trees that are
declining, so their appearance
on your fruit tree is a sign
something might be wrong
with the tree.
maintaining their vigour goes
a long way to prevent lichens
from growing on a plant.
Proper growing conditions
and soil fertility can stimulate
plant growth and inhibit
lichens. Lightly pruning limbs
covered with lichens, at the
right time of the year, can
help prevent the spread of
these organisms and stimulate
the fruit tree's growth.
Lichen on a bough of an apricot tree.
While lichens generally don't
harm the tree, too much
lichen can result in poor
growing conditions for the
fruit tree. For example,
lichens or fungus growing on
the leaves can interfere with
the photo synthesis process,
while a thick growth of
lichens on stems could add
extra weight that results in
damage to twigs.
Generally though, lichens are
nothing to be concerned
about in small numbers and
actually provide various
benefits. The larvae of
lacewings, which are benefi-
cial predatory insects that
prey on undesirable pests, use
lichens as camouflage. Several
species of birds and small
mammals also use lichens as facebook.com/gautengsmallholder
nesting material.
Lichens typically only affect
the appearance of the fruit
trees, and that is why you
may want to remove it. There
are no chemicals that can be
used against lichens, so you
will have to physically remove
them, being careful not to
damage the bark of the host.
Better still, focus on preven-
tion of lichen. Keeping the
fruit trees healthy and
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