Red witchweed

Alert

Be on the lookout for red witchweed and report any sightings immediately.

Reporting options

Red witchweed flowers

Red witchweed flowers

© Queensland Government

Red witchweed plant form

Red witchweed plant form

© Queensland Government

Red witchweed roots

Red witchweed roots

© Queensland Government

Red witchweed

Red witchweed

© Queensland Government

Native to tropical and semi-arid Africa, Arabia and Asia, red witchweed is a parasitic plant that grows attached to the roots of certain grasses. Its hosts include commercially important grasses and summer cereals such as sorghum, corn (maize), rice and sugar cane. It can also be found growing on a wide range of tropical grasses common on headlands and in pastures.

Red witchweed causes an estimated $7 billion of damage to grain crops in Africa each year. It is a prohibited invasive plant under the Biosecurity Act 2014.

Scientific name

Striga asiatica (syn. S. Lutea , S. hirsuta)

Similar species

Description

  • This parasitic plant attaches to roots of its host and grows 10–40cm above the ground.
  • Leaves are 6–40mm long and 1–4mm wide with tapered, pointed tips. They are arranged in opposite pairs along the stem.
  • Flowers are 5–20mm long and usually red but sometimes white, yellow or pink.
  • Seeds are very small.

3D model

  • View the 3D model to help you identify this plant. You can magnify the image and manipulate the view to inspect the plant from every angle.

Habitat

  • Prefers semi-arid savannas and grasslands, generally in tropics and subtropics, but can persist in warm temperate areas where suitable hosts exist.

Distribution

  • Occurs in 1 population in Queensland near Mackay.

Life cycle

  • Seeds only germinate when in close proximity to roots of a suitable host.
  • Seeds remain viable in soil for up to 15 years.

Impacts

Economic

  • Red witchweed affects corn (maize), millet, rice, sugar cane and sorghum.
  • It has the potential to become a serious pest.
  • The United States has spent more than $250 million on eradication from the Carolinas.
  • In Africa, heavy infestations can reduce grain crop yields by up to 70%.

How it is spread

  • Seeds spread primarily within soil (which can adhere to machinery, vehicles or contaminated produce such as mulch or seeds).
  • Seeds can also spread via imports such as contaminated grain, pasture seeds or organic fertiliser, and soil that has adhered to imported machinery.

Prevention

Control

Legal requirements

  • Red witchweed is a prohibited invasive plants under the Biosecurity Act 2014. You must not:
    • keep it
    • move it
    • give it away
    • sell it
    • release it into the environment.

    • If you do any of these, penalties may apply.

  • You must not take any action that is reasonably likely to exacerbate the biosecurity threat posed by red witchweed.
  • You must take any action that is reasonably likely to minimise the biosecurity threat posed by red witchweed.
  • You must report any sightings immediately using 1 of these methods:

Further information