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PAIA, 2000 (Act 2 of 2000) 

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Are these 'aliens' lurking in your garden?
16 April 2003
Araujia sericifera (Moth Catcher)
Araujia sericifera (Moth Catcher)

DO you have "aliens" in your garden that you don't know about? No, not the space variety, but the plant and tree varieties, quietly propagating and guzzling precious water in a city that has no large, natural water supplies.

These "aliens", defined in terms of Section 29 of the Conservation of Agricultural Resources Act, 1983 (Act 43 of 1983), are invasive plants and you should be looking out for them, so that you can take appropriate action to remove them from your garden.

Ronnie Kasrils, Minister of Water Affairs and Forestry, said in 2000: "Invading alien plants pose huge threats to our environment. The most detrimental effects are those that threaten our water reserves, livestock and carrying capacity of the land."

Currently, around 8% or 10 million hectares of South Africa is invaded by alien plants and trees, and that figure will double in the next 20 years if no action is taken to start eradicating these plants.

Kasrils goes on: "The fact that invasive plants remove 3.3 billion cubic metres of water from our rivers and dams each year is reason enough to be concerned."

Kasrils said that these plants should be considered to be major pests which are often spread deliberately by "well-meaning people acting on inadequate information". They compete with and seriously threaten the country's indigenous species, and play havoc with the eco-systems in which they appear.

"We will pay a hideous price for our ignorance," he warned.

Kasrils' department has set in place a programme to eliminate these aliens, called the Working for Water project, a seven year programme, so far giving jobs to 18 000 people methodically clearing waterways and wetlands.

Johannesburg residents can contribute to the efforts to eliminate these plants by becoming aware of what is growing in their own gardens, and systemically destroying these plants.

There are three categories of declared alien plants, and you might easily recognise some of them in your garden.

Here is a selection of the most common aliens in the three categories, with their common names in brackets:

Lantana Camara
Lantana Camara
Category 1: Declared Weed

The plants in Category 1 are: Lantana Camara (Lantana); Solanum Mauritianum (Bugweed bush); Pennisetum Setaceum (Fountain Grass); Pistia Stratiotes (water lettuce); Doxantha unguis-cati (Cat's Claw creeper); Araujia sericifera (Moth Catcher); Cereus Jamacaru (Queen of the Night).

The trees are: Robinia Pseudoacacia (Falfi acacia); Robinia Pseudoacacia (Black Locust); Acacia Mearnsii (Black Wattle); Melia Azedarach (Syringa).

Category 1 plants and trees must be removed and destroyed immediately.

Category 2: Declared Invader

The most common Category 2 plants include: Rorippa Nasturtium Aquaticum (Watercress); Gleditsia Triacanthos (Honey Locust); Populus x Canescens (Grey Poplar); Salix Babylonica (Weeping Willow); Acacia Melanosylon (Australian Blackwood); Acacia Dealbata (Silver Wattle); Agave sisalana (Sisal Hemp); Hypericum perforatum (St John's Wort); Psidium guajava (Guava); Salix babylonica (Weeping Willow).

Category 2 plants and trees may only be grown under controlled conditions.

Acacia Elata (Pepper Tree Wattle)
Acacia Elata (Pepper Tree Wattle)
Category 3: Declared Invader

Category 3 invaders include the following: Acacia Elata (Pepper Tree Wattle); Cotoneaster Franchetii (Orange Cotoneaster); Ligustrum lucidum berries (Chinese wax-leaved privet); Ligustrum Ovalifolium (Californian privet); Cotoneaster Pannosus (Silver-leaf Cotoneaster); Eriobotrya japonica (Loquat); Ipomoea purpurea (Morning Glory); Jacaranda mimosifolia (Jacaranda); Phytolacca dioica (Belhambra); Psidium cattleianum (Strawberry Guava).

Category 3 trees may not be planted at all.

Johannesburg water utility Rand Water indicates that all three categories of plants are permitted in biological control reserves, which are areas specially designated for the breeding of biological control agents.

If you have queries regarding alien plants and trees, call Rand Water's Call Centre on 0860 10 10 60.

Full list

For the full list of invasive plants and trees go to the Agricultural Geo-referenced Information system web site


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Last Updated on 25 March 2010