Weedy in the wrong place
Location: nationwide Distinctive features: blue-grey foliage, bright yellow fluffy flowers from July to September, followed by straight, hairless seed pods (5-10cm long). Why is it weedy: produces many long-lived seed and suckers when roots are damaged. Grows rapidly, and tolerates hot to cold temperatures, poor soils (fixes own nitrogen), damp to dry conditions, and damage. Possibly allelopathic (able to produce toxins that poison the soil to discourage growth of other plants).
Silver wattle is a problem depending on where you are. DOC consider it a weed, but control is only recommended where wattle is a recent threat, of low incidence or poses a high ecological threat, eg to native bush.
It can be any size, from shrub to large tree. Its frond-like leaves (20-30cm long) are arranged alternately on stems and have bluish, narrow leaflets, hence the name. Big clusters of numerous fluffy yellow flowers appear from July to September, followed by straight, hairless seed pods.
It’s a problem when it forms large, dense, long-lived stands in disturbed habitats. Native forest species establish under wattle so long-term impacts are usually confined to open and low-growing vegetation types. Rotting matter affects water quality. Large stands increase water run-off in winter, less in summer, causing seasonal drought and flooding.
HOW TO CONTROL IT
1. Hand pull or dig seedlings (all year round). Ensure minimum soil disturbance. 2. Cut and squirt (all year round): make 1 cut every 100 mm around the trunk, apply triclopyr 600 EC (5ml) per cut.
3. Bore and fill (all year round): make 1 hole every 200 mm around the trunk, apply metsulfuron-methyl 600g/kg (3mg) or triclopyr 600 EC (10ml) per hole.
4. Cut down and paint stump (all year round): triclopyr 600 EC (100ml/l) or Yates Hydrocotyle Killer (500ml/l) or metsulfuron-methyl 600g/kg (5g/10l) or Vigilant gel. 5. Spray (spring-summer): triclopyr 600 EC (30ml/10l) or Yates Hydrocotyle Killer (15ml/l).
2 THINGS WATTLE DOES WELL
• Wattle provides good cover for tall-growing native species so these sites can be left to regenerate (20-40 years) if it’s in the right place (with a seedbed of tall natives). • It is a great firewood, growing fast in tough conditions (salty areas, drought) and can be coppiced.