Bathurst bur
Asteraceae - Xanthium spinosum
BioSecurity

What does it look like?

Bathurst bur is a spiny plant that grows up to 1m tall; it has well-branched upright stems with triple spines grouped in opposite pairs. The leaves are three-pronged, narrow and pointed with a white midrib above and a whitish colour on the underside. Bathurst bur has inconspicuous flowers and the fruit are bur-like with hooked spines.

Bathurst bur can adapt to a wide range of climatic conditions, although it prefers moist soil, as it has a high water requirement. It is usually found on fertile, disturbed or bare ground, particularly in pasture and cultivated areas.

Why is it a problem?

Bathurst bur is a highly invasive weed and can quickly dominate large areas, out-competing crops, forage plants and native flora. It spreads entirely by seeds, which are within the spiny burs. Seed may lie dormant for many years before germinating, forming a very long-lived seed bank.

Control Methods

Site management:

  • Avoid soil disturbance and bare ground.
  • Maintain good pasture cover to prevent re-establishment.
  • Replant with native species where appropriate.

Recommended approaches:

  1. Grub out plants before flowering (March to April).
  2. Spray before plants set seed (1g metsulfuron + 20ml penetrant/10L or 120ml Tordon Max/10L or 25ml clopyralid/10L or 100ml glyphosate/10L).
    Do not use clopyralid in home gardens.

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