The battle of the weeds in the Kruger National Park is far from over. Since famine weed (Parthenium hysterophorus) was first recorded in the park in 1991, the problem has increased considerably. Kruger receives approximately R8 million per year from the Department of Environmental Affairs to fight famine weed alone.
The aggressive weed presents in most of southern Kruger, and is known to take over valuable grazing and pose health risks. While park management is addressing the problem with bugs, results will only be seen over the long-term.
Dr Llewellyn Foxcroft, SANParks scientist for invasion says the problem “is running away from us”. Teams in the field are constantly searching for new populations to keep it south of the Sabie River, but due to its short lifespan it is difficult to control before it seeds. A single plant releases thousands of seeds within six weeks of germination.
Thembeka Thwala monitors and maps invasive species in Kruger. The aim is to check the density and distribution and detect new species or distributions. “Panthenium occurs mainly in the Sabie and Crocodile rivers with a few plants at Orpen and Satara,” Thwala says.
Although it is difficult to get rid of the weed, there are ways to try control it. Manual pulling is viable for small populations. “We still apply herbicide where we can,” says Foxcroft. However, the herbicide requires constant follow-up and reapplication.
Biocontrol agents might be the last hope. These are bugs that are natural enemies in the plant’s home country of South America, and they target the leaves, seeds and stems of the weed. In March, teams released stem-boring Listronotus setosipennis and seed-feeding Smicronyx lutulentus at Crocodile Bridge. “It is still too still early to confirm whether biocontrol is effective or not,” says Thwala.
Famine weed was first recorded in South Africa in 1980, but became a problem after Cyclone Demoina in 1984. It spread through KwaZulu-Natal and eSwatini (Swaziland), dispersing along rivers and by vehicle from road verges.
The poisonous plant spreads rapidly, kills other plants and is harmful to animals and humans. Livestock that ingest the weeds produce milk and meat unfit for human consumption. People exposed to famine weed can experience asthma, bronchitis, hay fever and eczema.
Written by: René de Klerk
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