Alien Plant Control – Read more here


Alien plants are those which originate in a country other than South africa. They do not belong here, they should not exist and pose a huge threat to our indigenous, natural plant species. Alien plants are ususally so well adapted and competitive that they out-compete and eventually even displace indigenous plant species. In 2002 more than 10 million hectares (equivalent to 6.82% of South Africas land mass) was thought to be covered by alien plants. They use around 3300 million cubic metres of water per year and cost millions of rand to remove. Unfortunately a number of alien species can be found on Pidwa, originating from different countries having travelled here in different ways. Some, such as the Queen of the night cactus, was deliberately brought here by humans as an ornamental plant. Others, such as the common thorn apple, came accidentally in horse fodder many years ago.

Control of these plants varies from mechanical to biological and chemical removal methods. These aliens are causing decline in species diversity through local extinction of indigenous species. The resutling ecological imbalance could have catastrophic consequences such as increased flooding and this will all most definitely lead to decreased productivity of the land.

Project aims: To rid Pidwa of all alien plant species competing with the indigenous plant population. 

What’s being done? A variety of control methods are being used against the different species on Pidwa. The plants targeted and removal techniques can be seen in the volunteer section.

The role of volunteers: Volunteers carry out plant clearing sessions during which the following plant species are treated using the methods explained.

  • Lantana control – Lantana plants are mechanically cut down using pangas and saws and herbicide is applied to the cut stems to prevent re-growth. Theses plants can also be sprayed with herbicide and this is necessary to prevent coppicing from cut stems.
  • Common thorn apple control – These plants are simply pulled out the ground, root and all and left to the side to die.
  • Prickly pear control – This succulent cactus is injected with an herbicide called MSMA to kill it. Biological control is also effective against this species at certain times of year. Two insects in the form of a beetle and a mealy bug have been obtained from the government “Working for Water” scheme. These insects act as natural pests against the pear and can be artificially distributed between plants to kill them off.
  • Queen of the night control– These succulents are also injected by the MSMA herbicide. Generally these cacti are too large for treatment by the biological control used for Prickly pear.
  • Moon cactus control – This is another succulent and both the MSMA herbicide and biological control are effective in killing it.
  • Yellow oleander control – These plants are cut down and then burnt. Stems are treated with herbicide to prevent re-growth.


© Askari Wilderness Conservation Programme

1 Responses to Alien Plant Control – Read more here

  1. phenyo says:

    your inform is very helpful thanks

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