Weeds in South Australia

Weeds are plants that grow wild and have negative impacts on primary industries, native vegetation or human health. The cost of weeds to Australian agriculture is more than $4 billion each year.

Many weeds, particularly those that invade bushland, rivers and coasts are escaped garden plants. Weed risk assessment is now used to determine the weed potential of new plant introductions to Australia.

Declared plants

Declared plants are weeds that are regulated under the Natural Resources Management Act 2004 due to their threat to primary industry, the natural environment and public safety.

Plants are declared under the provisions of the Act relating to their movement, sale, notification and control.

Natural Resources Management boards oversee control programs for declared plants in each region.

Alert weeds

Some declared plants are also alert weeds because they are not yet established in South Australia and pose a serious threat.

Early detection is important so the plant can be destroyed before it becomes a serious problem.

Opuntioid Cacti

Opuntioid cacti are major weed threats to South Australia’s livestock industry, and environment. The Managing Opuntioid Cacti in Australia manual provides best practice information for managing these pests.

Silverleaf nightshade

Silverleaf nightshade is a deep-rooted perennial weed threatening crops and pastures in this State, and also a Weed of National Significance. A national best practice management manual has now been published.

Statewide management plans

Plans for specific weeds have been prepared to guide coordinated management programs:

Weeds of National Significance (WoNS)

WoNS are Australia’s most invasive plants. They have proven social, economic and environmental impacts that require national action to manage. There are national programs and strategies for each WoNS.

Wheel Cactus and African Boxthorn control and demo site

Wheel Cactus and African Boxthorn are classed as WoNS. A trial and demonstration site has been established in the Mid-North of South Australia to compare the effectiveness of aerial and mechanical control of African Boxthorn, and to demonstrate various ‘traditional’ chemical treatments for both species.

Read more about the Wheel Cactus and African Boxthorn trial and demonstration site.


For state policy advice

Biosecurity SA - Invasive Species Unit:

For regional control advice

  • Landscape South Australia: Landscape boards
  • National Pest Alert Hotline (Freecall): 1800 084 881
Page Last Reviewed: 29 Jun 2018
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