Bathurst burr

Native to South America, Bathurst burr is a small shrub with yellow-spined burrs. It was introduced to Australia in the early 1800s in contaminated grain or livestock imports.

Bathurst burr is a common weed in many parts of the world, including Australia, where it is widespread. Bathurst burr can contaminate wool, poison stock, and compete with crops.

Bathurst burr is not a prohibited or restricted invasive plant under the Biosecurity Act 2014.

Scientific name

Xanthium spinosum

Description

  • Annual herb growing into erect, multi-branched plant up to 1m tall (usually 30-60cm).
  • Leaves are dark green on upper surface, paler green underneath, up to 7cm long, usually 3-lobed, with cream mid-vein.
  • Stems are branched, with one or two 3-pronged yellow spines at base of each leaf stalk.
  • Flowers are creamy green, small, developing into straw-coloured burrs.
  • Burrs are 1-1.5cm long, with numerous yellow-hooked spines.
  • Each burr contains 2 seeds.

Habitat

  • Prefers drier areas such as well-drained contour banks and lighter soils.
  • Occurs along roadsides, old cultivation paddocks and irrigated pastures or watercourses.

Distribution

  • Occurs in southern, western and central Queensland but seldom in tropics.

Life cycle

  • Germinates late spring to early summer.
  • Produces burrs in February and dies in early winter.
  • Seeds can germinate out of season.

Affected animals

  • Sheep
  • livestock

Impacts

Economic

  • Contaminates wool, increasing processing costs.
  • Competes with summer crops.
  • Hosts fungal diseases that can poison stock.
  • Seeds are poisonous to domestic stock animals.

How it is spread

  • Burrs attach to animals, clothing, shoes etc, easily dispersing seed.
  • Burrs float and can spread along watercourses.

Control

Physical control

  • Cultivation is effective in seedling stage.

Herbicide control

  • Spraying with herbicides is effective, especially on young plants before burrs form.

See the Bathurst burr fact sheet (PDF, 515KB) for herbicide control and application rates.

Biological control

  • Bathurst burr seed-fly (Euaresta bullans) and rust Puccinia xanthii may have limited effectiveness.

Legal requirements

  • Bathurst burr is not a prohibited or restricted invasive plant under the Biosecurity Act 2014. However, by law, everyone has a general biosecurity obligation (GBO) to take reasonable and practical steps to minimise the risks associated with invasive plants and animals under their control.
  • Local governments must have a biosecurity plan that covers invasive plants and animals in their area. This plan may include actions to be taken on certain species. Some of these actions may be required under local laws. Contact your local government for more information.

Further information