Also known as
Where is it originally from?
What does it look like?
Sharply spiny shrub (<2-3 m tall) with woody erect or spreading stems which are many-branched in younger plants but become bare at the base as the plant gets older. Leaves are reduced to spines, new leaves less so. Spines are deeply furrowed. Pea-like yellow flowers (13-20 mm long, May-Nov, sometimes all year) are followed by hairy seed pods (13-25 mm long) which turn black when mature and explode to release seeds.
Why is it weedy?
Produces massive numbers of long-lived seeds, matures and grows rapidly, and is versatile about habitat. Tolerates hot to cold temperatures, high to low rainfall, wind, salt, damage and grazing, and all soil types.
How does it spread?
Explosion of seed pods spreads seed up to 5 m from the parent plant, and seed is also spread by soil movement and road graders, contaminated machinery, animals, boots, stock food and lime. Hedges, roadsides, waste land, farms, quarries, forest tracks, metal dumps, fire breaks, exotic forests, skid sites, and riverbeds are all common seed sources.
What damage does it do?
Forms pure associations temporarily in many habitats, inhibiting the establishment of native plant seedlings. Increased nitrogen in poor soil types (eg. gumland, sand dunes) may change the types of species present and nature of habitats to the detriment of specialised plants, eg herbs, orchids, low ferns. Can have positive impacts on bared ex-forest sites as it acts as a nursery crop for native species, adds nitrogen, humus, windbreak and shade, and opens up when older and disappears when overtopped. Succession to native species may be less likely on dry sites.
Which habitats is it likely to invade?
River systems, shrublands, forest margins, coastline, tussockland, fernland, wetland, consolidated sand dunes, gumlands, cliffs, disturbed forest, exotic plantations, poor pasture, and bare land.
What can I do to get rid of it?
1. Introduce biocontrol agents wherever possible - check with your regional council for more information on this.
2. Stump swab: glyphosate (250ml/L) or metsulfuron-methyl 600g/kg (2g/L) or triclopyr 600 EC (250ml/L) or a product containing 100g picloram+300g triclopyr/L (100ml/L) or picloram gel.
3. Spray (spring-summer): triclopyr 600 EC (20ml/10L) or triclopyr 300 EC (40ml/10L).
4. Spray (autumn-winter): metsulfuron-methyl 600g/kg (5g/10L+ penetrant - knapsack) or (20g/100L + penetrant - spraygun) or a product containing 100g picloram+300g triclopyr/L (250ml/100L spraygun).
5. Frilling: With a sharp chisel or axe, make a deep cut into the sapwood at regular intervals around the base of the tree, taking care not to ring-bark the plant. Immediately saturate each cut with undiluted a product containing 100g picloram+300g triclopyr/L .
6. Injection method: As each hole is drilled saturate it with undiluted a product containing 100g picloram+300g triclopyr/L using a sheep drench pack with a spraygun.
What can I do to stop it coming back?
Stumps resprout quickly. Reseeds profusely, especially after fire, disturbance or non-selective spraying. Do not burn or graze. Only use glyphosate spray when all vegetation on site is to be bared for replanting (generally not recommended). Maintain humus layer. Sites with appropriate tall forest species present can usually be left to be overtopped, can speed by selective slashing, stump swabbing or planting. Maintain roadsides, cuttings and other vectors, check road gravel and fill.