(Striga species)

Image: Witchweed, © Marco Schmidt.

Status of witchweed in Tasmania

  • Witchweed is a declared weed in Tasmania under the Tasmanian Weed Management Act 1999. The importation, sale and distribution of witchweed are prohibited in Tasmania.
  • The legal responsibilities of landholders and other stakeholders in dealing with witchweed are laid out in the witchweed Statutory Weed Management Plan.

What does witchweed look like?

  • Witchweeds are yellowish-green annual herbs growing to 30 cm high. Witchweeds are parasitic plants that penetrate the roots of host plants and extract water and nutrients. The stiff branching stems are covered with coarse short hairs. The leaves are linear-shaped. Flowering is in summer/autumn. The flowers vary in colour from red to white, and the seeds are dust-like and long-lived. The roots of witchweed are a thick tuft, most of which is attached to the roots of the host plant.
  • Upon germination, witchweeds send out an infection peg that penetrates the root of a host plant. The host plant is severely weakened by the parasitic witchweed withdrawing water and nutrients.
  • Witchweeds produce enormous amounts of seed, with 400 to 500 seeds contained in a single seed capsule. Seed is spread during cultivation, on machinery, tools and people, and as contaminants of crop seed.

Impacts of witchweed

  • Witchweed is one of the world's most serious crop weeds, particularly in Africa, and can reduce yields by 95 to 100%.

Where does witchweed occur?

  • Witchweed are native to tropical Africa and Asia.
  • There are no naturalised populations of witchweed in Australia.

What you need to do

  • If you locate witchweed anywhere in Tasmania, or if you find a plant that you think could be witchweed, immediately contact Biosecurity Tasmania on 03 6165 3777 to report this weed.

See also
Witchweed Statutory Weed Management Plan
Weed Links and Resources

Other useful links
Pest Genie

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