Bathurst Burr

Xanthium spinosum

Bathurst Burr

Image credit: Dragos Moise

Bathurst Burr is an annual summer-growing weed that produces spiny burrs.

It is a pest plant in pastures and degrades wool quality. 

It is a declared weed under the Natural Resources Management Act 2004 (NRM Act).

Description

  • an erect, branching herb that grows to 30 to 60 cm high
  • plants mainly germinate in late spring following rain
  • under irrigation plants will germinate throughout spring and summer, if the weather is warm
  • stems are greenish-yellow and hairy
  • the base of each leaf stalk is armed with 3-pronged yellow spines, up to 2.5 cm long
  • leaves are dark green and shiny above and pale and downy underneath
  • plants flower throughout the year, but mostly in summer and autumn. Most plants die in early winter
  • burrs are usually produced in late summer and autumn. They are covered with slender yellow hooked spines and contain two seeds
  • seeds remain dormant in the soil for at least three years.

Impacts

  • impacts on grazing, mainly in perennial pastures
  • can also affect rotational pasture/arable land use
  • the burrs are a contaminant of fleeces, especially when summer rainfall is high
  • burrs irritate the hands of shearers and can break the combs of shearing machines
  • can infest irrigated horticulture crops, such as grapes and tomatoes, where the burrs are a nuisance to pickers.

Distribution

  • Bathurst Burr is a native of South America but has now spread to most temperate areas of the world
  • has been considered a noxious weed in South Australia since 1862
  • the plant is mainly an annual and benefits from high soil moisture over summer
  • major areas of infestation are dams, drains and the flood-out areas of creeks and rivers
  • a poor competitor with established pasture and establishes best in trampled or overgrazed areas
  • burrs attach to the fur and wool of animals and are readily transported by stock
  • common infestation areas include stockyards, camps, roadside drains and overflow areas around troughs.

Hygiene practices

  • the best control measure for Bathurst Burr is to prevent spread
  • good hygiene practices for the movement of stock, hay, seed, produce and machinery greatly reduce the possibility of new infestations
  • maintaining good pasture cover is effective in suppressing Bathurst Burr.

How to control this weed

  • Bathurst Burr is highly visible when growing and control in pasture is readily achieved with common selective herbicides or spot spraying with non-selective herbicides
  • for advice on chemical control techniques contact your nearest Natural Resources Centre
  • refer to the 'Weed control handbook for declared plants in South Australia' for advice on chemical control. You can find it on the Biosecurity SA website.

Declarations

The following sections of the NRM Act apply to Bathurst Burr in the Adelaide and Mount Lofty Ranges region:

  • 175 (2) Cannot transport the plant, or any material or equipment containing that plant, on a public road
  • 177 (1) Cannot sell the plant
  • 177 (2) Cannot sell any produce / goods carrying the plant
  • 182 (2) Landowner must control the plant on their land
  • 185 (1) NRM authority may recover costs for control of weeds on roadsides from adjoining landowners

More information

For more detailed information download the fact sheet.

Please contact us for advice and assistance with controlling Bathurst Burr.

Natural Resources Adelaide and Mount Lofty Ranges