Parkinsonia

Parkinsonia is a declared Class B and Class C weed and a Weed of National Significance.

Go to the Weeds of National Significance website for more information.

Another name for this plant is Parkinsonia aculeata.

Parkinsonia - infestation 

Identification

You should use this as a guide. There may be other plants or weeds that look similar.

If you are unsure, contact the Weed Management Branch.

Habit

These features describe the habit of this plant:

  • thorny, branched, spreading tree
  • up to 6m high.

Parkinsonia - habit 

Stems and branches

These features can identify the stems and branches:

  • bright green branchlets
  • thin zig zag pattern
  • sharp, woody spines along the stems.

Parkinsonia - stems and roots 

Leaves

These features can identify the leaves:

  • green
  • drooping compound leaves
  • numerous oval leaflets 1 to 3mm long.

Parkinsonia - leaves 

Flowers

These features can identify the flowers:

  • small and yellow
  • five petals
  • positioned along the stalk.

Parkinsonia - flowers 

Fruit and seeds

These features can identify the fruit and seeds:

  • pods are green to pale brown
  • 5 to 10cm long
  • small constrictions between hard, oval seeds.

Parkinsonia - fruit and seeds 

Similar looking plants

The following plant species look similar to parkinsonia:

Mimosa Bush 

Mimosa bush (Acacia farnesiana) is native to Central and South America. It is a rounded shrub or small tree that forms thorny thickets that hinder mustering and stock access to water. It is not a declared weed in the NT.

This table (85.5 kb) can help you to identify a prickle bush that might be mimosa.

Impact

Parkinsonia infests nearly one million hectares, and threatens the agricultural and environmental values of over three-quarters of the Australian mainland.

Parkinsonia can have all of the following impacts:

  • creates dense, impenetrable thickets that can be several kilometres across
  • restricts mustering
  • blocks access to water
  • displaces native plants and animals
  • changes stream flows and gives shelter to feral animals, particularly pigs
  • dams watercourses, causes erosion and lowers watertables in wetlands
  • takes over large areas of floodplain
  • threatens significant wetland areas, national parks and other regions of high aesthetic, Indigenous and tourism value.

Habitat and distribution

Parkinsonia is native to Central and South America, Mexico and southern USA. 

It may have been introduced to Australia in the late 19th century as a shade tree for planting around water bores, dams and homesteads.

It is now found in established thickets throughout semi-arid Australia with infestations in Western Australia, the Northern Territory, Queensland and northern New South Wales. 

Parkinsonia is well established on the Barkly Tableland, in the Victoria River district and Gulf regions and occurs in various densities across most of the NT.

It can grow in a wide range of climatic and soil conditions. Once plants are established, they can tolerate heat and drought.

Spread prevention

The seed pods can float and are often carried down drainage lines and rivers for long distances. The seeds have a thick and extremely hard coat and can stay viable in the soil for many years.

It can spread widely during flooding events and can be spread in mud sticking to machinery, animals and footwear. Animals will often not eat the seeds, but they have been known to eat and spread seeds when there are limited choices for food, especially during drought. Mass germination events may occur following flooding, enabling the establishment of dense thorny thickets if not controlled early.

You can prevent the spread of parkinsonia by doing all of the following:

  • map infestations to help develop a management plan
  • control minor infestations, isolated outbreaks or seedlings first
  • prioritise control along waterways, bore drains and dams to reduce spread
  • always control plants upstream first
  • increase community awareness to help find and control the species
  • designate wash down areas and actively work to prevent contamination of clean areas
  • monitor areas that you have treated and watch for re-infestations.

Parkinsonia - spread 

Control

Blade-ploughing, stick-raking, bulldozing and chaining can be effective if the root layer is removed from the soil. 

Cultivation of pasture or native vegetation after mechanical control will help to prevent re-sprouting and seedling establishment. 

Fire destroys seed in the soil surface and can be used as a follow-up to remove seedlings after other control efforts. 

Fire may also be used to manage mature trees. 

Hand grubbing for single plants or small outbreaks, ensure removal of the root system. Biocontrol options are available.

Chemical control

The best time to treat parkinsonia is from March to May. Below is a list of treatment methods that can be used.

Chemical and concentration Rate Situation, method and notes
Aminopyralid 8 g/L + Triclopyr 300 g/L + Picloram 100 g/L
Grazon® Extra

350ml / 100 L
3 L / ha
Seedling (individuals and infestation):
Foliar spray - avoid spraying if plants are stressed or bearing pods - Uptake Spraying Oil required
Foliar spray - plants up to 2m or two years old - Uptake Spraying Oil required
Triclopyr 240 g/L + Picloram 120 g/L
Access®
1 L / 60 L (diesel)
1 L / 60 L (diesel)
Seedling or adult (individuals or infestation):
Basal bark < 5cm stem diameter
Cut stump > 5cm stem diameter
Tebuthiuron 200 g/kg 1.5g / m2 Seedling or adult (individuals or infestation):
Granulated herbicide - ground applied
Do not use within 30m of desirable trees or apply to continuous area > 0.5 ha
Do not use if fire is eminent
Apply when there is soil moisture or prior to rain

Basal bark and cut stump treatment can be done at any time of the year.

Basal bark - This method involves spraying around the whole stem up to 30cm from the ground.

Cut stump - the plant is cut off low to the ground and chemicals are applied to the exposed surface of the stump.

Non-chemical control

Hand pulling and grubbing

Weeds, including their roots, are physically pulled out of the ground by hand or using hand tools. 

This is an effective method of control for individual weeds and recent outbreaks that haven’t released seeds yet, but it requires a lot of labour.

Blade ploughing

A blade plough is used to push over some woody shrubs and sever their roots underground. 

Bulldozing

Bulldozers, chopper rollers or graders are used to clear large weed infestations. This leaves large areas of soil exposed so follow up control or revegetation should be considered.

Stick raking

A large blade with teeth attached to a bulldozer is used to clear large weed infestations. This leaves large areas of soil exposed so follow up control or revegetation should be considered.

Chaining

A large heavy chain is dragged across the ground by heavy machinery to push over and pull out large weeds. This method is useful for removing roots and providing access for burning.

It works best at the end of the wet season when the ground is soft and roots are easier to pull from the soil, but has been successful in prickly acacia control where dense stands are dry or in drought.

Fire

Fire as a management technique is most effective when it is used together with other methods. It is useful for mass seedling control if there is a sufficient fuel load.

Revegetation

Re-planting native vegetation or desirable pasture or crop species creates competition for the weeds that are present and is especially useful when weeds have been removed as an established desirable plant will compete with the new weed seedlings as they emerge.

Biocontrol

The parkinsonia biological control program is a collaboration between CSIRO and the Northern Territory, Queensland and Western Australian governments.

See the How to manage weeds page for more information about the parkinsonia biocontrol program.

Last updated: 27 June 2017