Opuntioid cacti - prickly pear

Opuntioid cacti are declared Class A and Class C weeds across all of the Northern Territory (NT).

All opuntioid cacti species in the genera Austrocylindropuntia, Cylindropuntia and Opuntia are weeds of national significance except for the Indian fig (Opuntia ficus-indica) which is a crop plant. The Indian fig is included in the NT Class A and Class C declarations in the NT.

Get the cacti fact sheet (3.1 mb) and find out where to get a free cacti wheelie bin sticker (1.5 mb).

For more information go to the Weeds of National Significance website.

Opuntioid cacti - 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:

  • appearance can vary significantly between species
  • range from low growing shrubs to erect trees up to 8m tall
  • generally branched shrubs
  • usually around 2m tall
  • most are covered with spines.

Opuntioid cacti - habit 

Stems and branches

These features can identify the stems and branches:

  • all have small to large flattened stem fragments commonly referred to as pads
  • most are covered with spines between 1cm and 5cm long.

Opuntioid cacti - stems and branches 

Leaves

These features can identify the leaves:

  • leaves are shed early
  • the flat stem segments are often misidentified as leaves.

Opuntioid cacti - leaves 

Flowers

These features can identify the flowers:

  • appearance can vary significantly between species
  • more commonly yellow, red and orange in colour
  • generally present in spring and summer.

Opuntioid cacti - flowers 

Fruit and seeds

These features can identify the fruit and seeds:

  • most reproduce vegetatively but some produce viable seed
  • some produce bright, large fruit that are attractive to birds.

Opuntioid cacti - fruit and seeds 

Impact

Opuntioid cacti can have all of the following impacts:

  • spines can cause serious injury to humans, stock and native animals
  • can form large stands that harbour feral animals
  • limits access for mustering and recreational activities
  • spines can contaminate wool and hides
  • infestations can reduce or prevent grazing activities, reducing productivity.

Habitat and distribution

Native to the Americas, opuntioid cacti can grow throughout a wide climatic range. 

Species are found throughout all Australian states and territories, growing across varied soil types in areas that receive above 150mm of rainfall annually. The majority are drought-resistant and hardy.  Many species were deliberately introduced as food, fodder, ornamentals and for the former cochineal industry.

Some species have since proven to be highly invasive, others flourish in disturbed areas such as dumps and disused mine sites.

The common prickly pear (Opuntia stricta) is found throughout the NT. Indian fig (Opuntia ficus-India) and riverina pear (Opuntia elata) are also common.   There are no known specimens or infestations of Austrocylindropuntia spp. in the NT.

Spread prevention

Opuntioid cacti mostly spread via plant segments which break off and are distributed by animals, water, machinery, vehicles and people. Some species also produce viable seeds within large, bright coloured fruit that are spread by birds and other animals.

You can prevent the spread of opuntioid cacti by doing all of the following:

  • map infestations to help develop a management plan
  • control minor infestations, isolated outbreaks or seedlings first
  • designate wash down areas and actively work to prevent contamination of clean areas
  • remove all segments and fruit from an area as they can regrow even under harsh conditions
  • monitor areas that you have treated and watch for re-infestations.

Opuntioid cacti - spread 

Control

Chemical control

Below is a list of treatment methods that can be used.

Chemical and concentration Rate Situation, method and notes
Triclopyr 600 g/L
Garlon™ 600
800ml / 60 L (diesel) Seedlings, juvenile, adults (individuals or infestations):
Foliar spray entire plant surface, ensuring all plant surfaces are completely covered with spray-mix to the point of runoff. Avoid spraying plants that appear stressed.
Triclopyr 240 g/L + Picloram 120 g/L
Access™
1 L / 60 L (diesel) Seedlings, juvenile, adults (individuals or infestations):
Foliar spray entire plant surface, ensuring all plant surfaces are completely covered with spray-mix to the point of runoff. Avoid spraying plants that appear stressed.

Non-chemical control

Any form or physical removal must remove all parts of the plant as they can regenerate from small fragments. For this reason large scale removal such as bulldozing is not effective and in fact will cause opuntioid cacti to spread further.

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.

Alice Springs and Tennant Creek residents are encouraged to Bin it Don’t Spread It by getting cacti out of your garden before summer sets in. You can now dig out your declared cactus and put it into your wheelie bin for collection and removal to the waste management facility.

Biocontrol

In the past control of the prickly pear with the agent cactoblastis has been highly successful, however biological control with insects requires a heavier density of plants than is present in the NT.

Last updated: 08 August 2017