Time to clear garden of invader plants

WEEDBUSTER Week has been a campaign encouraging the public to identify and remove invasive alien plants from gardens. While it comes to an end today, the war on invasive alien plants in gardens should be ongoing.

WeedBuster Week represents the annual culmination and highlight of the ongoing campaign aimed at the management and containment of invasive alien plants.

The campaign is a multi-departmental initiative, led by the Department of Environmental Affairs through the National Resource Management Programmes (NRMP) and supported by various partners and stakeholders.

Invasive alien plants (IAPs) are plants which have been introduced to South Africa, either intentionally or unintentionally. They have established natural populations and are spreading out of control to the detriment of indigenous vegetation and water resources.

IAPs are problematic because they are highly adaptable, vigorous plants that easily invade a wide range of ecological niches. They have invaded more than 10 million hectares of land to date. Experts maintain that more than 7% of all water run-off is lost to invasive alien plants, which use 3.3 billion cubic metres of water – much more than their indigenous counterparts, reducing South Africa’s water security.

These plants also threaten our rich biodiversity by replacing indigenous and endemic vegetation. This, in turn, will threaten species that are dependent on indigenous plants for food and shelter. They are also detrimental to agriculture, threaten food security and are known to exacerbate the intensity of fires, flooding, erosion and siltation.

Invasive garden plants in the Eastern CapeBe on the lookout for the following garden plants which have been identified in Eastern Cape gardens: inkberry (Cestrum laevigatum), lantana (Lantana camara), pampas grass (Cortaderia selloana), morning glory (Ipomoea indica), queen of the night (Cereus jamacaru), torch cactus (Echinopsis spachiana), silky hakea (Hakea sericea), oleander (Nerium oleander), bugweed (Solanum mauritianum) and Australian myrtle (Leptospermum laevigatum).

The law and invasive speciesThere are currently 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 South Africa and if they grow in your garden, they should be removed and destroyed immediately. Trade in these plants is prohibited.

How to remove invasive plants from your gardenWhen seedlings appear, they can be pulled out. 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. Consult your local garden centre for advice. Avoid dumping cuttings and removed plants in open landfill sites, as these may take root and spread.

Celebrating biological controlSouth Africa is a world leader in the field of biological control and it has been the official theme of this year’s WeedBuster Week. Biocontrol involves the use of a plant’s natural enemy and include insects, mites and fungi. The first biocontrol agent released in South Africa was against the drooping prickly pear (Opuntia monocantha), which was a problem along the South African coast.

Biocontrol agents are now used with great success to control Port Jackson willow, rooikrans, bugweed, water hyacinth and a range of other invasive plants.

For more information on the identification and removal of invasive alien plants, visit the Invasive Species South Africa website: www.invasives.org.za

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