From page 11
BIOCONTROL
infected material can be cut,
and redistributed.”
Those of us who observe how
the weed has spread through-
out Gauteng probably view
this progress and impact as
being rather slow, when we
just want the plants to die and
disappear altogether.
Therefore it is important to
understand what biological
control is and that very few of
the agents released on
invasive plants ever eradicate
the host plant. At best they
will reduce the weed to
acceptable levels.
The thrips are distributed to all
interested parties without cost,
however the insects need to
be collected from the ARC
Roodeplaat PHP office.
A database is kept with
contact details of people
wanting to release thrips and
the ARC-PPRI supply insects
accordingly, when available.
Landowners can e-mail Ms v
d Westhuizen on
[email protected] if
they want their names to be
added to the list.
Researchers have found that
thrips establishment is also
linked to the time of release
and therefore landowners
should familiarise themselves
with the characteristics of
pompom re-growth early in
the season. Adult thrips prefer
young, soft plant material.
Late releases on mature,
flowering plants are seldom
successful.
“We try to extend the window
period for release of the thrips
during the flowering period by
requesting landowners to cut
pompom back to allow for re-
growth before making a
release. Early season (Sept-
Nov) releases are therefore
ideal.”
It is also hoped that the leaf
rust, Puccinia eupatorii, which
was discovered in 2006 on
field populations of pompom
in Pretoria will also help to
diminish the weed. Since
then, pompom rust has spread
through wind dispersal to
most areas invaded by the
weed.
In November 2013, an
augmentative release strategy
for pompom rust was
implemented at field sites in
Gauteng and has caused some
dieback throughout the
growing season, resulting in
less rootstock growth and seed
production.
Pompom weed threatens
grasslands, open savanna and
wetlands by decreasing the
carrying capacity of the land.
The plant is unpalatable to
wildlife and agricultural
livestock and causes skin
irritations to animals.
Classified site grows
like Topsy
W
ith the number of
visitors to our new
Small Farmers
Online Exchange classified
advertising website fast
approaching 20 000 per
month, in turn generating
more than half a million page
hits monthly, www.sasfox -
.co.za is becoming the website
of choice for smallholders and
small farmers to buy and sell
their produce and equipment.
Among the facilities we
introduced on the site is a set
of pages designed to allow
small producers to sell or
swop their produce, or their
kitchen production. Thus if
you grow your own vegeta-
bles, or if you are an artisinal
cheesemaker, for example,
there are pages on which you
can advertise your produce.
How you choose to part with
your stuff is also up to you:
you can sell it, or you can
swop it with other small
producers for items or
produce that you desire but
don't produce yourself.
13
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