Gauteng Smallholder Gauteng Smallholder November 2011 | Page 35

IN THE ORCHARD
The meaning of lichen on your trees
T
rees are so important
on smallholdings, for a
number of reasons, so
when we see lichen growing
on any of them, particularly
our fruit trees, we might
become concerned.
Lichen ~ pronounced “liken”
~ is a grey, green or yellow
patch that we sometimes see
on trees, rocks, shrubs or
even on buildings.
It is actually a complex
From page 31
ment must also include how
you manage the grazing.
In order to decrease the
parasite load in the pasture,
you should reduce the length
of stay in a pasture, by
rotating amongst camps.
Chances are you!ve seen lichen
on your trees, but do you know
what it is and what it does?
organism, consisting of fungi
and algae or bacteria growing
together in symbiosis.
Symbiosis means that two
organisms are growing
together, usually in a relation-
ship that benefits both.
The fungus needs a partner
that can carry out photosyn- thesis. Fungi are incapable of
photosynthesis because they
lack the green pigment
chlorophyll. Fungi cannot
harvest light energy from the
sun and generate their own
nourishment in the form of
carbohydrates. Instead, they
need to seek out outside
Ticks do not survive for long
on pasture that is either
heavily grazed and thus short
and dry, or in areas where
pasture land is rotated with
crops. When intensively
farmed land is fenced it is
possible for cattle pastures to be cleared of ticks by a
combination of management
and acaricide use, and then
maintained tick free. Burning
of pasture grasses kills many
ticks but should only be used
when the main reason is to
improve grazing availability.
You might also need to spray
the pens where the livestock
are kept at night.
TICKS
33
www.sasmallholder.co.za
sources of food.The algae or
bacteria live inside the
fungus, and exchange
nutrients with it.
Cyanobacteria also provide
fungi with the additional
benefit of nitrogen fixation. In
return, fungi provide the
algae and cyanobacteria with
a protected environment,
especially from damaging
ultraviolet rays.
Lichens are key players in a
variety of environmental
processes. The lichen
sometimes contributes to
Continued on page 35