NEWS
Figure 2: The destruction of fire to a
stand of wattle in Harrismith Figure 3: Coppice of wattle after a fire
(Bergville) Figure 4: Chromolaena invading the
edge of a coastal forest in KZN
Figure 5: Regrowth of Pompom weed,
a month after a fire Figure 6: Pompom weed is a big in-
vader of South Africa’s inland grasslands Figure 7: Regrowth of Bramble in Kark-
loof, after an annual burn
fin weed, dry season fires can be carried
into the forest when the weed ignites.
Under the right conditions fires can be
used to control the plant in veld areas
because it is semi-woody with a shallow
fibrous root system. However, it should
never be used to control the weed in in-
digenous forests. ter, so wildfires pass harmlessly over-
head. However, the heat stimulates the
rootstock to resprout before grass can
regrow and the shoots form a thick,
leafy canopy that smothers emerging
grasses (Figure 5 and 6). Wildfires
Indigenous forests take decades to re-
cover after a wildfire and are susceptible
to invasion by many other species that
are harder to kill than paraffin weed.
Biocontrol against this weed is recom-
mended in indigenous forests.
Pompom weed
Pompom weed (Campuloclinium mac-
rocephalum) is a grassland invader and
is most troublesome on the Highveld. It
is a perennial herb that produces annual
stems from an underground rootstock.
Unlike paraffin weed, it does not pose a
direct fire threat but rather an ecologi-
cal one.
The plant is dormant in soil during win-
Grassroots
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Fire significantly increases the density of
pompom weed on the Highveld. How-
ever, it has also been found to destroy
seeds on the soil surface and kill germi-
nating seeds in the topsoil, which means
that it can be used to control the weed
as part of a holistic treatment plan.
Controlled burning can be combined
with herbicides to kill regrowth, attack-
ing both seeds and plants in quick suc-
cession. Regrettably, fires are seldom
followed by spraying, so the problem
continues to worsen despite access to
cost-effective control options.
American bramble (Rubus cuneifolius)
also produces stems from rootstock
underground. Like pompom weed, in-
festations are worst in veld that burns
regularly (Figure 7).
March 2020
Uncontrolled fires not only destroy the
habitat of fauna and flora, but the loss
of topsoil and changes to soil structure
also permanently influence which plants
grow at the site.
Other knock-on effects include loss of
biodiversity, carrying capacity and pro-
ductivity.
In contrast, controlled fires are a pow-
erful tool in the holistic management of
fire-prone vegetation, but the risks are
significant and the line between success
and disaster is fine.
Wildfires can cause major damage and
farmers need to carefully evaluate their
fire prevention strategies to prevent
their farms from becoming tinderboxes.
–Jeremy Goodall, ARC Plant Health and
Protection
For more information, contact the au-
thor on 033 355 9413 or send an email
to [email protected].
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