Archive for December, 2013

The danger of alien plants

My thriller THE PEGASUS PROJECT is fiction but this warning, issued by agricultural scientists, demonstrates the all too-real-danger of an alien plant running out of control.

Toxic plant threatens farms, health

Durban – One of the world’s worst invader weeds is spreading across KwaZulu-Natal and the eastern parts of the country, threatening to overrun the crops of subsistence farmers, choke game reserves and possibly cause serious skin allergies and other health problems for people.

The white-flowered Parthenium plant from Central America – also known as “famine weed” in India and Ethiopia where it has caused major crop losses for poor farmers – is toxic to people and animals and contains chemicals which can poison the soil and roots of a variety of crops and plants.

In Bangalore and other parts of India, up to 20 percent of people in heavily infested areas were reported to have developed severe allergic reactions to the plant, including skin rashes, asthma, hayfever and blistered skin.

In Ethiopia, sorghum crop yields dropped by as much as 97 percent because of dense infestation, while studies in Australia estimated that beef farmers suffered multimillion-dollar losses after pasture land was overrun.

In South Africa, the weed has spread into northern KZN from Swaziland and Mozambique. Although the heaviest infestation is still north of the MfoloziRiver, the prolific seeds of the weed have “leap-frogged” their way as far south as Durban.

Ezemvelo KZN Wildlife ecologists are so worried by the rapid spread that they have suggested setting up spray-booths to wash down high-risk vehicles entering major game reserves.

This is because seeds can get stuck in the mud and dust underneath cars and trucks which have passed through heavily infested areas.

Ezemvelo ecologist Ian Rushworth told a conservation seminar last week the weed could mature from a seed to a flowering plant in just four weeks and continue to reproduce throughout the winter months in some areas of KZN.

“The invasion in South Africa is relatively recent but is happening with alarming speed, and this species is likely to become the most damaging invasive alien species ever encountered,” Ezemvelo ecologists warned in a draft strategy document on how to contain the problem.

“We have a very short window of opportunity to get on top of it. But if we leave it for another season it will be very difficult to stop this species getting out of control,” said Rushworth.

So far, there have been no reports of human skin allergies or respiratory problems in KZN associated with the plant, although black rhinos in the Phongola Nature Reserve were photographed earlier this year with swollen eyes and bright pink lips while browsing in an area with dense stands of famine weed.

One of the reasons for the rapid spread is the ability of adult plants to generate up to 15 000 viable seeds each.


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