“Biological control is about supporting the eventual clearing operations” Dr Alan Wood.

Alien invasive plant species threaten biodiversity, reduce water run-off, and increase risk of fire in the Overberg. Flower Valley has been working to control the spread of alien invasive plants for the past 21 years. One of the successful methods is through the release of organisms that inhibit the production of seed stock, and reduce growth and spread of an alien invader. This is known as biological control mechanisms (biocontrol).

Flower Valley Conservation Trust coordinated a successful biological control workshop for interested landowners in the Overberg region on the 25th of November 2020. The workshop aimed at providing landowners with the knowledge and practical skills to release and monitor biological control agents on targeted alien plant species. Hearth and Soul Eco farm in Akkedisberg Conservancy hosted the venue, and biocontrol expert Dr Alan Wood generously shared his knowledge with the group.

This conservancy and neighboring areas have high infestation of Hakea species. Hakea originates from Australia and is well adapted to the South African Mediterranean climate and fire. Hakea is able to spread profusely in the absence of natural predators. Two species occur in the Overberg: Hakea gibbose (rock hakea) and Hakea sericea (silky hakea). Hakea often grows in dense, impenetrable forests, and spreads high into the mountains making it inaccessible to remove through conventional clearing.


Planned releases of biocontrol in 2021 will be coordinated by Flower Valley through the support from the Department of Environment, Forestry and Fisheries (DEFF), and the Drakenstein Trust.

Thank you to Dr. Alan Wood from the Agricultural Research Council’s Plant Protection Research Institute for leading the workshop. Special thanks to Sybille Nagel for providing the venue and snacks, and all the landowners who attended.



  • It is a long-term solution to the reduce the spread of alien species
  • It is one of the most cost-effective ways to control alien species
  • Biocontrol will never remove the species completely
  • When biocontrol is released, the organism has undergone extensive trials to make sure it does not damage other species.