Acacia mearnsii

Black wattle

Family: Fabaceae

Origin: Australia

A black wattle bush with a cluster of yellow white fussy flowers in the centre and hundreds of tiny leaves branching out from the centre.
Flowers are pale yellow or cream-coloured followed by black to reddish brown seed pods.
Photo credit: Forest and Kim Starr

Regional Pest Management Plan (RPMP) status

  • Whole region — Sustained control
  • Hauraki Gulf Controlled Area Notice pest

View more about the RPMP statuses

General description

Tree. Leaves are dark green and bi-pinnate. Flowerheads are globose, cream, and borne in racemes July – September. Seed pods are < 90 x 7 mm and are straight or slightly curved.

What you need to know

To help protect our environment, from 1 September 2021, you:

  • will not be allowed to breed, distribute, release or sell black wattle within the Auckland region.
  • will not be allowed to plant black wattle within the Auckland region, unless you are transferring an existing plant on your land to another location within the boundaries of the same property.
  • must destroy any black wattle on land that you occupy if it has been planted in breach of the above rules and you are directed to do so by an authorised person.

Habitats

Shrubland, scrub, coastal areas, cliffs, riparian margins, roadsides, wasteland, grassland, plantation margins.

Dispersal

Seeds dispersed by gravity.

Impact on environment

Forms dense stands, competing with other plant species in scrubland, coastal areas and riparian margins. Nitrogen fixer. Alters soil chemistry, moisture content and microbial function.

Control

Site Management

Follow up treated areas 3 times per year. Encourage natural regeneration of native plants or replant treated areas where possible after 2-3 treatments to establish dense ground cover and minimise reinvasion.

Follow up treated areas 3 times per year. Crown lift to allow understory plants to establish or to underplant prior to controlling large trees.

Recommended approaches

Physical control

Method: Dig out.

Plant parts requiring disposal: Seeds.

Disposal options: Trees can be chipped and used as mulch, preferably when not in seed.

Biocontrol

Biocontrol is currently not available for this species.

Community agrichemical control recommendations

No qualifications: Cut stump and paste freshly cut base of stems with double strength glyphosate gel or ringbark and paste cut with double strength glyphosate gel.

Basic Growsafe certified: Foliar spray seedlings with 200ml glyphosate green per 10L of water. Ringbark and spray cut with 750ml glyphosate green per 1 L of water.

Certified Handler/Experienced agrichemical user: Drill and inject trees with 750ml glyphosate green and 10ml penetrant per 1L of water, if safe to do so. Drill 18mm holes (tangentially angled downwards) in a spiral up the trunk.

For 50mm stems drill one hole. For 100mm stems drill two holes. For larger stems drill holes 150mm apart. Foliar spray seedlings with 200ml glyphosate green per 10L of water and 20ml penetrant.

Safety notes

Large trees must not be drilled or ringbarked that are closer than 1.5 times the height of the tree from paths, walkways and property. Trees over 4 metres in height should be removed by a qualified arborist.

Caution: When using any herbicide or pesticide please read the label thoroughly to ensure that all instructions and safety requirements are followed.

A black wattle bush with a cluster of yellow white fussy flowers in the centre and hundreds of tiny leaves branching out from the centre.
Flowers are pale yellow or cream-coloured followed by black to reddish brown seed pods.
Photo credit: Forest and Kim Starr
A sprawling black wattle bush with clusters of flowers in the centre.
Black wattle have feathery, bifurcated leaves.
Photo credit: Forest and Kim Starr