Aliens are tough adversaries

Please be warned: This is, without a shadow of doubt, what Tanzania will
face if the government does not act immediately against Parthenium and
chromoleana, both recently found in the country. We urgently need an early
detection rapid response initiative to prevent the disaster that is facing
Swaziland.

Regards
Sue

MBABANE, 8 June (IRIN) - The effects of Cyclone Demonia are still being
felt a quarter of a century after it ripped through landlocked
Swaziland. The once-in-a-generation storm system swept in from the
Indian Ocean and across neighbouring Mozambique, devastating
infrastructure and sowing death among the Swazis, but its lasting legacy
was the alien plant seeds that the winds carried.

Unnoticed at first, the demonia weed (Parthenium hysterophorus),
colloquially named for the cyclone, has decimated indigenous hunting
areas that people relied on for game, as well as the recently
established community nature reserves that hoped to use wildlife as a
tourism drawcard.

Demonia is native to Mexico, Central and South America; on the Indian
Ocean island of Reunion, where the Swazi seeds are thought to have come
from, demonia is known as camomille z'oiseaux.

It grows up to 1.5 metres tall and can create severe allergic
reactions among humans. "The Demonia weed releases an irritating
chemical that animals find repellent; wherever the weed has taken root,
game animals vacate," botanist Linda Dobson told IRIN.

The invasive plants are worsening food insecurity in a country where
about one-fifth of the roughly one million people depend on food aid.
"Areas which were pristine twenty years ago have been overrun by
invasives," Dobson said. This pushes up the costs of agriculture because
resources are diverted to keep clearing arable land.

"We have a huge alien invader problem here in Swaziland. They bring
with them an increased risk of catastrophic events, such as floods and
landslides; they are hindering farmers' ability to produce crops and
raise cattle," Dobson said.

The Natural History Society of Swaziland has noted invasive plant
species, such as the triffid weed - Chromolaena odorata, an invasive
species from Central America that spreads rapidly, smothering local
indigenous plants - has colonized the country's lowveld, leading to
regions becoming devoid of indigenous antelope.

The noxious triffid weed, known locally as sandanezwe, has been the
subject of government information campaigns. "The problem with
sandanezwe is that it is toxic to cattle, but it has taken over grazing
areas. With nothing to eat the cattle starve," Andrew Dlamini, a field
extension officer in charge of community education at the Ministry of
Agriculture, told IRIN.

In 2009 a programme was launched to eliminate sandanezwe from
government-owned farms, but it became mired in allegations of corruption
and was suspended in late 2009, but others have pointed to the
stubbornness of the triffid as the cause.

"It is not enough to cut it [the triffid weed] - it has to be dug out
and burned; otherwise, it is like a zombie that keeps coming back to
life again and again. Some people in government did not understand this,
and when the weed returned to crop-growing areas that had supposedly
been cleared of sandanezwe, they blamed it on incompetence or
corruption," an agriculture ministry researcher, who declined to be
named, told IRIN.

"Its seeds are viable for a half a century, and are brought to life by
fire - that is why the triffid weed has been so successful at taking
over the northern highveld, because those hills are burned by bush fires
twice a year."

Cultural historian Jabulani Ndwandwe commented: "Swazis ... were
unprepared when nature started behaving in ways no one understood, and
strange plants took over the grazing lands and waterways."

The water hyacinth (Eichhornia crassipes), originally imported into
South Africa from South America to beautify artificial ponds, found its
way into the ecosystem and spread across the border into Swaziland.

"These 'water weeds' literally choke rivers by removing nutrients,
because as they spread out they block sunlight. Everything below them
dies. Their seeds are viable for up to 30 years, and can lie dormant.
You look at a lake covered by hyacinths and it appears as a green field;
the fish are gone, which further reduces Swazis' food supply, and the
water quality is affected," Dlamini said.

Zinde Mthimkhulu, Senior Water Engineer and Hydrologist at the
Ministry of Natural Resources, told IRIN that invasives like eucalyptus
trees, which can consume 1,000 litres of water each day, were a threat
to the water table. "The deep-rooted invasives pose a problem because
Swazis depend on boreholes during the dry months and the invasives
compete for aquifers."

Mthimkhulu said a national policy was needed to police invasive plants
in the water supply, but the necessary surveys and studies to inform any
such policy were lacking.

jh/go/he[ENDS]


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