Acacia: declared pest

Page last updated: Monday, 20 July 2020 - 2:47pm

Please note: This content may be out of date and is currently under review.

Several non-native acacias (Acacia species) are declared pests in Western Australia (WA). This article describes the nature of the plants with links to requirements land owners/occupiers must adhere to, pest control methods and how to search, detect and report it.

Includes: Bolivian wattle, white ball acacia (Acaciella angustissima formerly Acacia boliviana), camel thorn, giraffe thorn (Acacia erioloba), cutch tree (Acacia catechu), fever tree (Acacia xanthophloea), karroo thorn (Vachellia karroo formerly Acacia karroo), prickly acacia (Vachellia nilotica formerly Acacia nilotica), red thorn (Acacia gerrardii), soap nut (Acacia sinuata) and umbrella tree (Acacia tortilis).

Form: tree/shrub - perennial

Status: present in WA


Trees and shrubs sometimes spiny. One species, prickly acacia (Acacia nilotica) is a Weed of National Significance (WoNS).

Leaves: bipinnate, that is they are divided twice and give a feathery appearance.

Flowers: grouped into dense globular or cylindrical spikes, either in the axils of the leaves or at the end of branches.

Thorns: non-native acacia can be distinguished from native acacia by their large thorns.

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Agricultural and economic impact

Acacias can be very invasive. For example, karroo thorn acacia could potentially invade large areas of South West, Western Australia. It can form dense thorny thickets reducing agricultural productivity and loss of native habitat.

Declared pest category

The Western Australian Organism List (WAOL) contains information on the area(s) in which this pest is declared and the control and keeping categories to which it has been assigned in Western Australia (WA). Search for Acacia species in the WAOL using the scientific name Acacia. Each Acacia species in WAOL has a declaration and declaration map.

Requirements for land owners/occupiers and other persons

Requirements for land owners/occupiers and other persons if this pest is found can be sourced through the declared plant requirements link.

Search > detect > report

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Pest and Disease Information Service (PaDIS)
+61 (0)8 9368 3080

Detectability: medium difficulty to find. Karroo thorn is a tree with yellow flowers, similar to Australian wattles. Its most distinctive feature is large pale thorns growing along the younger stems in V-shaped pairs – these thorns can be up to 100 millimetres long. Karroo thorn could be confused with some thorny garden trees that are not declared, but these have red or brown thorns. Any other tree with long pale thorns in pairs is likely to be other exotic Vachellia or Acacia species. All exotic Vachellia and Acacia species should be reported.

Who should look for it: potentially anyone in the South West Land Division could find karroo thorn including biosecurity groups, local governments, general public, home gardeners, farmers, permaculturists, the nursery industry and any horticultural professionals.

When to find it: karroo thorn could be found at any time of year.

Where to find it: karroo thorn is most likely to be found in cultivation. Karroo thorn and similar species have previously been found in several Australian states in home gardens, botanic gardens and zoos.

Control method

Report the presence of any acacia with thorns before undertaking a control measure. Control methods for this declared plant can be found on DAFWA's acacia control web page.

Management calendarTable displays: Search Jan-Dec. Germination Nov-Feb. Actively growing Jan-Dec. Flowering Dec-Feb. Fruiting: Mar-Aug. Treatment Jan-Dec. Manual removal Jan-Dec.

Contact information

Pest and Disease Information Service (PaDIS)
+61 (0)8 9368 3080
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