Hudson pear (Cylindropuntia pallida)

Also known as: prickly pear, cactus, cacti

Hudson pear is an invasive cactus species of Mexican origin that has naturalised in a variety of habitats in north-western NSW.

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How does this weed affect you?

Hudson pear is an invasive cactus species of Mexican origin that has naturalised in a variety of habitats in north-western NSW. It seriously degrades invaded land and ecosystems and is continuing to spread.

Hudson pear was first detected in Australia in the Lightning Ridge area during the late 1960s. It is believed to have spread from a cactus nursery at Grawin. Some reports state that this process was aided by opal miners who deliberately used the plants to protect their diggings from nocturnal prowlers and thieves but these are unable to be verified.

If left unchecked, it has the potential to reduce the viability of agricultural enterprises and subsequent land values and impact adversely on native fauna and flora. Its presence on flood plains in north-western NSW is particularly worrying as a major flood event could result in a significant increase in its distribution including movement into the Darling River system.

The plant is named after a resident of the Lightning Ridge area, Mr Hudson, who first brought the problem to the attention of the then Prickly Pear Destruction Commission and the cactus is still referred to as Hudson pear.

Hudson pear has particularly vicious spines which are capable of penetrating footwear and even vehicle tyres.

Spines are encased in a detachable sheath which may remain embedded in a wound even after the body of the spine is removed. The spines are capable of causing serious injury to humans, livestock and working animals such as horses and dogs and may present a severe impediment to mustering operations.

Hudson pear also poses a threat to native fauna and has caused the deaths of native animals such as koalas. Infestations of Hudson pear can also displace native flora and may impact on biodiversity.

What does it look like?

Hudson pear is a branched cactus which grows to 1.5 m high and to 3 m wide, with a cylindrical trunk and rope-like segments. The segments are cylindrical with those above the trunk reaching 90 cm long and 4 cm wide.

Depressions on segments (areoles) contain small bristles (glochids) and clusters of 4–8 spines. The spines may reach up to 3.5 cm in length on the outer segments. The outer layer of the spines separates into a paper-like, detachable sheath during the first year of development, a characteristic that Hudson pear shares with other Cylindropuntia species.

Plants have pink flowers, about 5 cm wide, containing stamens with golden anthers and filaments that are pink towards the anthers and cream towards the base. The stigma is pale yellow. Fruit is wider towards the apex, never in chains and 2–4.5 cm long.

Older fruit have few spines and are much less spiny than younger fruit.

Cylindropuntia pallida is possibly a hybrid between Cylindropuntia tunicata, which it resembles, and another as yet undetermined species. These two species occur in the same area but are easily separated when in flower. Cylindropuntia pallida has pink flowers and white spines while C. tunicata has yellowish-pink flowers and straw-coloured spines.

Where is it found?

In NSW most plants are in north-western NSW especially around the opal mining areas of Lightning Ridge, Grawin and Glengarry and at Cumborah. Plants have also been found in the Central West, Hunter and Greater Sydney regions.

Estimates of the area of NSW infested range from 60,000 to 100,000 hectares. This species has also naturalised in South Africa.

Hudson pear occurs in a variety of habitats including eucalypt woodlands, alluvial floodplains, shrublands and rocky outcrops. It is currently mainly found on lighter soil types but will grow on most soil types.

Maps and records

• Recorded presence of Hudson pear during property inspections (Map: Biosecurity Information System - Weeds, 2017-2024)
  These records are made by authorised officers during property inspections under the Biosecurity Act 2015. Officers record the presence of priority weeds in their council area and provide this to the NSW Department of Primary Industries. Records reflect the presence of the weed on the date of inspection.
  
  

How does it spread?

Plants flower in late spring and summer. Hudson pear reproduces vegetatively and is believed to not produce viable seed. Like many other cactus species, Hudson pear spreads by movement of segments and fruit that root where they come in contact with the ground. The term ‘segments’ has been used here to cover both parts of the plant and fruit as they behave similarly.

Much of the spread of Hudson pear in the Lightning Ridge, Grawin and Glengarry areas appears to be associated with livestock, native and feral animals, vehicles, and water movement.

New plants are capable of growing from segments of all sizes.

Acknowledgements

Author: Royce Holtkamp

The following people kindly contributed to this publication: John Hosking, Stephen Johnson, Rachele Osmond, Alan Maguire, Andrew Storrie, Warwick Schofield (NSW DPI);
Maxine O’Brien (Lightning Ridge Miners Association);
Daryl Green (Western CMA);
Ian Kelly (Castlereagh Macquarie County Council);
Kerry Brougham (DEC).

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Control

Controlling Hudson pear using traditional methods, such as chemical application, is made more difficult by the types of terrain and vegetation in which infestations are located. As the plant occurs over an extremely large area, there is no possibility of successfully locating and destroying all cactus segments.

However, there is a place for traditional control techniques in an integrated approach to Hudson pear management. Core infestations would be best dealt with using biological control agents whilst targeting outlying areas with chemical applications or other conventional techniques such as physical removal.

Biological control agents, once established, would form self perpetuating populations that will gradually spread throughout the distribution of Hudson pear.

This Integrated Weed Management approach has the advantage of diverting limited resources to areas with the greatest potential impact as it is usually from these outlying infestations that a weed species spreads.

Mechanical / physical removal

Physical removal, while successful on isolated plants, is not recommended because of the danger of serious injury occurring during the process of removal. Once uprooted, plants need to be disposed of correctly to avoid new infestations arising from this material. Correct disposal methods include burying and burning. Adequate depth for burying has not been determined although some opal miners dispose of plant material down disused mine shafts. Burnt material requires checking for any regeneration. On larger infestations, physical removal is not viable because any missed plants or plant parts have the capacity to form new infestations if they come into contact with the ground and form roots.

Biological control

A cochineal bug, Dactylopius tomentosus ‘Californica var. parkeri’ lineage provides good control of Hudson pear. There are several species of Dactylopius that look similar but they each control different species of cactus. There is even a different subspecies of cochineal required for brown-spined Hudson pear. It is important to use the correct type of cochineal for each species of cactus. Contact your local weeds officer for information about using cochineal to control Hudson pear.

Preventing spread

It is extremely important that the spread of Hudson pear be limited. Vigilance is the key to preventing spread. Hudson pear segments of all sizes should be removed as these are capable of forming new plants/infestations if they come into contact with the ground and form roots.

When travelling in Hudson pear infested areas, take care not to leave designated roads. If you do need to travel off road, check vehicle tyres and undercarriage for any sign of Hudson pear and remove before leaving the area.

If you have been outside the vehicle, remember to check clothing, footwear, any other equipment which may have come into contact with the ground and even the inside of the vehicle for Hudson pear segments. Any animals or stock should also be checked.

Herbicides

When spraying herbicides, care needs to be taken to ensure total coverage of plants as any missed plants or segments have the capacity to form new infestations if they come into contact with the ground and form roots. This is easily achieved by the addition of a marker dye to the spray mix which makes sprayed plants highly visible. Thorough spraying of Hudson pear with herbicide mixtures that incorporate a spray oil are effective at any time of the year if the plants are actively growing and not stressed. Plants sprayed during cooler months may take longer to die than those treated during warmer months. In areas that regularly flood, avoid spraying when flooding is likely.

Spraying with herbicides may not be 100% successful, therefore the site should be monitored for regrowth and an appropriate follow-up treatment carried out if required.

Herbicide options

See Using herbicides for more information.

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Picloram 100 g/L + Triclopyr 300 g/L + Aminopyralid 8 g/L (Grazon Extra®)
Rate: 500 mL per 100 L of water.
Comments: Follow the label instructions as per Prickly pear (common), smooth tree pear. Spray actively growing plants. Thoroughly cover all of the plant with herbicide mix to the point of runoff. Regrowth may occur, so a follow-up application may be necessary. To improve uptake add a paraffinic oil at the rate of 500 mL per 100 L of water.
Withholding period: Where product is used to control woody weeds in pastures there is a restriction of 12 weeks for use of treated pastures for making hay and silage; using hay or other plant material for compost, mulch or mushroom substrate; or using animal waste from animals grazing on treated pastures for compost, mulching, or spreading on pasture/crops.
Herbicide group: 4 (previously group I), Disruptors of plant cell growth (Auxin mimics)
Resistance risk: Moderate

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Triclopyr 300 g/L + Picloram 100 g/L (Various products)
Rate: 500 mL per 100 L of water.
Comments: Follow the label instructions as per prickly pear common. To improve uptake of add a paraffinic oil at the rate of 500 mL per 100 L of water.
Withholding period: Nil.
Herbicide group: 4 (previously group I), Disruptors of plant cell growth (Auxin mimics)
Resistance risk: Moderate

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Triclopyr 600 g/L (Garlon® 600)
Rate: 1 L per 75 L of diesel
Comments: Follow the label instructions as per common prickly pear (Opuntia spp.). Spray actively growing plants. Thoroughly cover all of the plant.
Withholding period: Nil.
Herbicide group: 4 (previously group I), Disruptors of plant cell growth (Auxin mimics)
Resistance risk: Moderate

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Triclopyr 600 g/L (Garlon® 600)
Rate: 3 L per 100 L of water.
Comments: Follow the label instructions as per common prickly pear (Opuntia spp.). Spray actively growing plants. Thoroughly cover all of the plant to the point of runoff. To improve uptake, add a paraffinic oil at the rate of 500 mL per 100 L of water.
Withholding period: Nil.
Herbicide group: 4 (previously group I), Disruptors of plant cell growth (Auxin mimics)
Resistance risk: Moderate

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Biosecurity duty

The content provided here is for information purposes only and is taken from the Biosecurity Act 2015 and its subordinate legislation, and the Regional Strategic Weed Management Plans (published by each Local Land Services region in NSW). It describes the state and regional priorities for weeds in New South Wales, Australia.

Area	Duty
All of NSW	General Biosecurity Duty All pest plants are regulated with a general biosecurity duty to prevent, eliminate or minimise any biosecurity risk they may pose. Any person who deals with any plant, who knows (or ought to know) of any biosecurity risk, has a duty to ensure the risk is prevented, eliminated or minimised, so far as is reasonably practicable.
All of NSW	Prohibition on certain dealings Must not be imported into the state, sold, bartered, exchanged or offered for sale.
Central Tablelands	Regional Recommended Measure* (for Regional Priority - Prevention) Land managers should mitigate the risk of the plant being introduced to their land. Land managers should eradicate the plant from the land and keep the land free of the plant. A person should not deal with the plant, where dealings include but are not limited to buying, selling, growing, moving, carrying or releasing the plant. Notify local control authority if found.
Central West	Regional Recommended Measure* (for Regional Priority - Eradication) Land managers should mitigate the risk of the plant being introduced to their land. Land managers should eradicate the plant from the land and keep the land free of the plant. A person should not deal with the plant, where dealings include but are not limited to buying, selling, growing, moving, carrying or releasing the plant. Notify local control authority if found.
Hunter	Regional Recommended Measure* (for Regional Priority - Eradication) Notify local control authority if found. Land managers should eradicate the plant from the land and keep the land free of the plant. A person should not deal with the plant, where dealings include but are not limited to buying, selling, growing, moving, carrying or releasing the plant.
Murray	Regional Recommended Measure* (for Regional Priority - Prevention) Land managers should mitigate the risk of the plant being introduced to their land. Land managers should eradicate the plant from the land and keep the land free of the plant. A person should not deal with the plant, where dealings include but are not limited to buying, selling, growing, moving, carrying or releasing the plant. Notify local control authority if found.
North West Whole of Region, excluding Core infestations within Walgett shire	Regional Recommended Measure* (for Regional Priority - Eradication) Within exclusion zone: Land managers should mitigate the risk of the plant being introduced to their land. Land managers should eradicate the plant from the land and keep the land free of the plant. A person should not deal with the plant, where dealings include but are not limited to buying, selling, growing, keeping, moving, carrying or releasing the plant. Notify local control authority if found. Within core infestation: Land managers should mitigate the risk of the plant being introduced to their land. Land managers should mitigate spread of the plant from their land. A person should not buy, sell, move, carry or release the plant into the environment. Land managers should reduce the impact of the plant on assets of high economic, environmental and/or social value.
Northern Tablelands	Regional Recommended Measure* (for Regional Priority - Prevention) Land managers should mitigate the risk of the plant being introduced to their land. Land managers should eradicate the plant from the land and keep the land free of the plant. A person should not deal with the plant, where dealings include but are not limited to buying, selling, growing, moving, carrying or releasing the plant. Notify local control authority if found.
Western	Regional Recommended Measure* (for Regional Priority - Eradication) Land managers should mitigate the risk of the plant being introduced to their land. Land managers should eradicate the plant from the land and keep the land free of the plant. A person should not deal with the plant, where dealings include but are not limited to buying, selling, growing, moving, carrying or releasing the plant. Notify local control authority if found.
	*To see the Regional Strategic Weeds Management Plans containing demonstrated outcomes that fulfil the general biosecurity duty for this weed click here

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Reviewed 2024