Life is a Garden | South Africa |

5. What can the public do?

What you and I ...do.

IAPs grow quickly which makes them very popular garden plants. Old habits and favourites die hard. There was a big outcry when Carte Blanche announced that 70 000 jacarandas to be cut down in Pretoria as an April Fools Joke a few years ago.

Happily for its fans, the jacaranda is a category 3 plant and does not need be uprooted. However, as a gardener, you've got to be tough and wean yourself off those ‘grow-like-weeds' IAPs since you are responsible for what grows on your land.

1. Learn to identify IAPs
   The first thing to do is to get a list of the worst offenders. For a copy of the alien invader plant list, call 0800-005-376 or download a list from www.lifeisagarden.co.za
2. Look out for pictures of IAPs
   Then you may need some help in identifying the plants. See pictures of invasive alien plants at www.agis.agric.za/agisweb/wip.
3. Remove IAPs
   Next you need information on eradicating aliens. This normally involves a combination of:
   1) Mechanical felling, weeding by hand and controlled burning.
   2) Chemical killing with environmentally safe herbicides.
   Obtain advice on treatment methods by contacting the Working for Water WeedBuster toll free line 0800 005 376 or visit the DWAF website on http://www.dwaf.gov.za/wfw or contact 011 723 9000 (WFW Nurseries Partnership Programme).

It's darn hard work getting rid of invaders

To get rid of IAPs successfully you need three steps:

1. Initial control: drastic reduction of existing population
2. Follow-up control: control of seedlings, root suckers and coppice growth
3. Maintenance control: sustain low alien plant numbers with annual control

Aliens cost money

Declared weeds and invader plants are one of the most significant drivers of environmental changes worldwide. The American government estimates that invasive species account for 4% of the global Gross Domestic Product.

They contribute to social instability and economic hardship, placing constraints on sustainable development, economic growth and environmental conservation. The direct costs of weeds to a single country can amount to billions of dollars annually. Invasives could cost the American economy at least US$24 billion per annum in reductions in water run-off, biodiversity loss, ecosystem resilience, loss of productive land, increased costs of fire protection and erosion following fires.

It is estimated that alien invasions may have reduced the value of fynbos ecosystems by US$11,75 billion. The cost to clear plant invasions in South Africa could amount to US1,2 billion. South Africa spends R600 million a year removing invasive alien plants.

4. Plant good plants - Plant Me Instead

Having removed invasive alien plants from your garden, replace them with good plants. There are 27 000 indigenous plants in the country and 9000 exotic or alien plants in the country. Only 198 of the 9000 foreigners are deemed to be bad invaders. The Plant Me Instead Campaign in 150 garden centres nationwide offers information on the range of good plants available for ecologically minded gardeners to plant in their gardens. See www.lifeisagarden.co.za

FACTS ABOUT INVASIVE ALIEN PLANTS

• Did you know that New Zealand's Airport Control for Invasive Alien Species has twenty inspectors, stringent laws and harsh penalties for anyone bringing foreign plants or animals into the country?
• Did you know that Britain regards its outbreak of foot and mouth disease as an invasive alien virus which cost the UK tourism, trade and agriculture sectors over R135 billion (12,5 billion pounds).
• Did you know? Our indigenous flora is causing havoc in Australia! Our own indigenous watsonia, arum, gazania and agapanthus are regarded as invader alien weeds in Australia. Watsonias are a huge problem in Melbourne. Gazanias are a problem in Perth.

What happens if we do nothing?

If South Africa takes no action it is estimated that alien infestations will double in the next 15 years.

What else can you do to help?

If you own land, keep it clear of invasive alien plants.

• Do not buy invasive alien plants from nurseries, and do not support nurseries that sell such plants.
• Join a volunteer clearing or hack group
• Buy firewood, charcoal, crafts, furniture, toys, building material, mulch, etc made from invasive alien plants.
• Do not bring foreign plants and animals into our country or transplant them from other parts of our country - and do not send ours to other countries
• Inform authorities about landowners who are causing the spread of invasive alien plants.
• Encourage your local authority, agricultural union, school, community, etc to work with the Working for Water programme.

WfW toll free line 0800 005 376 or visit the DWAF website on http://www.dwaf.gov.za/wfw

Some poisonous garden ‘companions'

• The South American lantana (Lantana camara - category 1) is regarded as one of the world's ten worst weeds and occurs in 2,2 million hectares across South Africa. The green fruits are highly toxic and child fatalities have been recorded.
• The syringa (Melia azedarach - category 3) occurs in three million hectares of land across South Africa. The berries are highly toxic and fatalities have been reported.
• The small black seeds of the castor oil plant (Ricinus communis - category 2) are extremely toxic. One seed is enough to kill a child.

Invasive alien aquatic plants

Actively thriving colonies of water hyacinth may double their numbers every 11 to 18 days. Kariba Weed grows at an alarming rate - in two years it spread from 20 hectares to 40 000 hectares in the Kariba Dam.

• Roodeplaat Dam - North East of Pretoria: 70% of the dam is covered in a thick mat of water hyacinth endanging schools rowing.
• Benoni Lakes - the four Benoni lakes have been invaded by water hyacinth endangering leisure yachting.
• Roodekopjes Dam - north west of Brits and the centre of the bass leisure fishing industry is 20% covered in water hyacinth and has a big control programme.
• The Vaal River near Orkney had a 6km backup of water hyacinth behind chains

Even the smallest piece left behind will re-grow. And water hyacinth (Eichhornia crassipes - category 1) - is such a worldwide problem that a Global Working Group comprising over 30 scientists from 11 countries meets every two years to discuss control options for this single species. The danger is that an excess of these plants alters the pH of water, kills fish by blocking out sunlight, produce an excess of minerals, which in turn causes an increase of algae.

Vital statistics on invasive aliens

Only 15% of tree species introduced to South Africa are regarded as invasive. 750 tree species and 8 000 herbaceous species introduced into South Africa 1 000 introduced species are naturalised, 200 are invasive.

• 84 species introduced from South and Central America
• 14 from North America
• 30 from Australia
• 29 from Europe
• 36 from Asia
• 45% of species from Australia have become important pests

Did you know? IAPs have been around for a long time

Since 1652, when Dutch horticulturist Hendrick Boom set up a garden for the Dutch East India Company in Cape Town, exotics ranging from English oaks to Australian acacias have been arriving on our shores. For example, the timber industry introduced blue gums (Eucalyptus globulus) and black wattle (Acacia mearnsii) to KwaZulu-Natal in 1839 and by 1904 there were 75 000 hectares of wattle plantation in and around Durban.

THE WORST AQUATIC INVADERS

Remove and destroy. Water hyacinth must be destroyed by law, as the costs to taxpayers of controlling it when it takes over a dam out weigh any pleasure one may derive from having this plant in your water feature. Pic: Kay Montgomery

Remove and destroy. Water lettuce (Pistia stratiotes) is a highly ornamental invasive alien aquatic that should never be allowed to flourish in private ponds in the Eastern Cape. Pic: Lukas Otto

Remove and destroy. Parrot’s feather (Myriophyllum aquaticum), a South American floating aquatic plant with pale green, finely divided, feather-like leaves is a Category 1 invasive alien aquatic weed. Pic: Lukas Otto