[IRIN - MBABANE, 8 June 2010] - 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.
The demonia weed's scientific name is Parthenium hysterophorus
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.
Eradication campaigns failed
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
