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Balloon vine (Cardiospermum grandiflorum) produces pods.
Durban – Invasive alien plants, introduced to South Africa, are a threat to our rich biodiversity. They have established natural populations and are spreading out of control – to the detriment of indigenous vegetation and water resources.
They are highly adaptable, vigorous plants that easily invade a wide range of ecological niches.
They are also detrimental to agriculture and threaten food security, and are known to exacerbate the intensity of fires, flooding, erosion and siltation.
There are 198 invasive plants listed under three categories under the Conservation of Agricultural Resources Act.
Plants listed under category one may no longer be grown anywhere in SA and if they grow in your garden, they should be removed and destroyed immediately. Trade in these plants is prohibited.
The subtropical climate of Durban ensures prolific plant growth, but unfortunately the indigenous vegetation is being strangled by a proliferation of invasive alien plants. Some of the most problematic invasive plants from Durban gardens include lantana (Lantana camara), balloon vine (Cardiospermum grandiflorum), bugweed (Solanum mauritianum), castor-oil plant (Ricinus communis), triffid weed (Chromolaena odorata), Indian laurel (Litsea glutinosa), inkberry (Cestrum laevigatum), Mexican sunflower (Tithonia diversifolia), seringa (Melia azedarach) and yellow bells (Tecoma stans).
The Mexican sunflower (Tithonia diversifolia) is invading natural land and roadsides.
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SA is a world leader in the field of biological control and it is the official theme of this year’s Weed Buster Week. Bio-control involves the use of a plant’s natural enemy and include insects, mites and fungi. The first bio-control agent released in SA was against the drooping prickly pear (Opuntia monocantha), which was a problem along the SA coast.
Bio-control agents are now used with great success to control Port Jackson willow, rooikrans, bugweed, water hyacinth and a range of other invasive plants. Bio-control methods are mostly used where large areas have been invaded and where physical or chemical removal is not feasible.
What you can do in your own garden is remove seedlings when they appear. This is easiest when the soil is moist. Shrubs and small trees can be cut off and the crown and roots then removed from the soil. Large trees need to be ring-barked, which involves removing a ring of bark from the stem of the tree near ground level.
There are also a number of effective herbicides on the market. Avoid dumping cuttings and removed plants in open landfill sites, as these may take root and spread into neighbouring land.
National WeedBuster Week is an initiative by the Department of Environmental Affairs. Visit www.invasives.org.za – The Mercury
