The demise of the toxic shrub bellyache bush in northern Australia
is the aim of new research by the Tropical Weeds Research Centre in
Charters Towers.
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Bellyache Bush. Photo: Greg Calvert
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Despite control measures such as herbicides, bellyache bush is
still causing landholders headaches because of the large amount of
seedling regrowth that occurs once plants are treated. A new
project by the Tropical Weeds Research Centre—which is part
of Queensland’s Department of Natural Resources and Mines
(NRM)—is going to develop strategies to deal with initial
infestations and subsequent regrowth of bellyache bush.
NRM’s Dr Faiz Bebawi, who will lead the project, said
ecological studies would try to answer questions such as how long
seed remains viable in the soil once adult plants are removed and
how long it takes seedlings to mature and start setting seed.
Control techniques will include the use of chemicals, machinery and
fire.
Two study sites are currently being established in the Charters
Towers region: one at Larkspur Station on the Lynd Highway and the
other at Riverview Station on the banks of the Burdekin River.
One ecological study that has already begun is testing seed
longevity.
“We’ve also done a slashing trial at Larkspur Station
where we slashed the plant in summer, when the plant is actively
growing, and in winter when it is dormant,” said Faiz.
“In general, if you slash plants during summer you can kill
all the older plants but results were variable for younger plants
depending on the height at which they were slashed.
“However, if all the plants are slashed at ground level in
either season all of the plants can be destroyed. We have also been
trialing large-scale burns in riparian habitats as a means of
managing this invasive weed on a cattle station at Sandy Creek, 20
km north-west of Charters Towers.”
Faiz said the trials had been some of the most successful
undertaken for controlling the weed.
“Within the experimental plots, the first burn produced a
kill of 80 per cent of the Bellyache Bush.
“However, if that first burn was followed up with a second
burn 12 months later, a staggering 92 per cent of the weed was
killed. “Bellyache bush is very susceptible to fire but where
green fuel prevails, fire will not carry through. This is the main
reason why we could not achieve 100 per cent kill.”
Seedling survival and recruitment post-fire were also monitored.
Seedling recruitment was three-fold greater after the first burn
than in control plots.
“The trials have shown the follow-up burn is essential. If a
follow-up isn’t done, the 20 per cent of the weed that is not
killed will set seed and re-infest the area, a factor compounded by
the effects of the fire on seedling recruitment,” explained
Faiz. Bellyache bush, a native of tropical America is a garden
escapee, which has spread throughout northern Queensland, the
Northern Territory and into the Kimberley region of Western
Australia. In Queensland, the largest infestation is on the
Burdekin River and its tributaries where it is believed to infest
more than 40,000 hectares.
“The problem with bellyache bush is that it out-competes
native vegetation, reduces pasture growth and hinders
mustering,” Faiz said.
The fruits of the plant are also poisonous to humans and animals,
with a number of livestock deaths within Queensland and the
Northern Territory attributed to Bellyache Bush in recent years.
The project began in March 2001 and it is hoped that it will run
for 10 years, provided funding remains available. “Hopefully
at the end of the day we will have a wider range of control options
available and know a lot more about this noxious weed,” Fiaz
said.
Faiz is also interested in identifying potential study sites in the
wet tropics which have heavy infestations of bellyache bush.
Please contact him if you know of such a site.
