Pencil cactus (Cylindropuntia leptocaulis)

Also known as: Pencil pear, Christmas cactus, Pencil cholla

Pencil cactus is a shrub with very thin stems, pale yellow flowers and yellow to red fruit. It competes with native plants and pastures. Some plants have spines that can injure people and animals.

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How does this weed affect you?

Pencil cactus is a spreading shrub that:

• competes with native plants
• competes with pasture plants, reducing productivity
• has bristles and sometimes sharp spines, which can injure people and animals.

What does it look like?

Pencil cactus is a shrub up to 1.8 m tall with many spreading branches. Large plants have woody trunks. 

Stems (pads or cladodes) are:

• green, green grey or purplish
• cylindrical with rounded ends
• 2-8 cm long and 0.3-0.5 cm in diameter  
• often spineless but sometimes spiny
• easily detached. 

The stems have small, evenly spaced areas called areoles. Barbed bristles (glochids), spines, leaves, flowers, fruit, roots and new shoots all grow out of the areoles.

Areoles:

• are 3.5 mm long
• have up to 3 spines or may be spineless
• contain tufts of yellow or reddish brown bristles usually 1-3 mm long but may be up to 5 mm long
• contain white, grey or yellow woolly hairs. 

Spines are:

• straight or arching up or downwards
• reddish brown with yellow tips, aging to red brown
• covered with a greyish or creamish sheath 
• up to 4.5 cm long
• often absent.

Flowers are:

• pale to greenish yellow, sometimes tipped red
• up to 2 cm wide 
• mostly present from spring to early summer.

Fruit are:

• yellow to red when ripe (rarely green), sometimes tinged purple
• egg-shaped
• up to 2.7 cm long and 1.2 cm wide
• singular or in chains 
• fleshy, smooth and spineless
• sometimes on a stalk.

Seeds are:

• pale yellow
• round to squarish, toothed and warped
• up to 4.5 mm in diameter.

Similar looking plants

Pencil cactus looks similar to Klien's cactus (Cylindropuntia kleiniae), which has longer stems (up to 26 cm) and pink to red flowers.

Where is it found?

In NSW, most plants have been found in the North West.

Pencil cactus is native to north western Mexico and the deserts of USA. 

What type of environment does it grow in

Pencil cactus grows in arid regions in its native range. Plants tolerate high temperatures and droughts. 

In NSW it has been found growing:

• in Eucalyptus woodlands.
• along roadsides
• in pastures.

Maps and records

• Recorded presence of Pencil cactus during property inspections (Map: Biosecurity Information System - Weeds, 2017-2026)
  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 have been spread by people planting pencil cactus in gardens.

By seed

Seed viability in Australia is not known. In its native range most spread is by plant parts rather than seed. Seed can be spread by animals that eat the fruit and spread the seed in their droppings.

By plant parts

The stem segments break off very easily and new plants grow from the stems when they come in contact with the soil. If the stems have spines, they are easily spread by attaching to vehicles or animal skin, feathers or fur.  Stems can also be spread by people dumping garden waste.

References

The Australian Virtual Herbarium. Occurrence records for Cylindropuntia leptocaulis. Retrieved 25 September 2024 from: https://avh.ala.org.au/occurrences/search?q=taxa%3A%22Cylindropuntia+leptocaulis%22#tab_mapView

Flores-Torres, A., & Montaña, C. (2012). Recruiting mechanisms of Cylindropuntia leptocaulis (Cactaceae) in the southern Chihuahuan desert. Journal of Arid Environments, 84, 63-70.

Harvey, K.J., McConnachie, A.J. Sullivan, P. Holtkamp, R. & Officer, D. (2021). Biological control of weeds: a practitioner's guide for south east Australia. New South Wales Department of Primary Industries, Orange.

PlantNET (The NSW Plant Information Network System). Royal Botanic Gardens and Domain Trust, Sydney. Retrieved 24 September 2024 from: https://plantnet.rbgsyd.nsw.gov.au/cgi-bin/NSWfl.pl?page=nswfl&lvl=sp&name=Cylindropuntia~leptocaulis.

Sheehan, M. R., & Potter, S. (2017). Managing Opuntioid Cacti in Australia: Best Practice Control Manual for Austrocylindropuntia, Cylindropuntia and Opuntia Species. Department of Primary Industries and Regional Development.

VicFlora (2024). Flora of Victoria, Royal Botanic Gardens Victoria.  Retrieved 25 September 2024 from: VicFlora: https://vicflora.rbg.vic.gov.au/flora/taxon/f1364a35-360b-4200-921c-d4202b3d8768 

More information

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Control

Successful weed control relies on follow up after the initial efforts. This means looking for and killing regrowth or new plants. Using a combination of control methods is usually more successful.

Prevention

To prevent the spread of pencil cactus do not grow it in gardens or pots. Do not take cuttings of unknown cactus plants to grow out or share with others.

Stop the spread of cactus into new areas by checking clothing, vehicles and equipment for plant parts before leaving an area that has any cactus plants.

By hand

Dig up small plants in isolated infestations. Wear appropriate protective clothing and gloves to protect against injuries from spines if present.

By machine

Dense infestations or large plants may be controlled by machinery if the site is not environmentally sensitive. Dig out all of the roots. Dispose of all plant parts to avoid regrowth. Clean plant fragments from the machinery before leaving the site.

Disposal

Dispose of pencil cactus by burying all parts of the plant at least one metre deep or by burning in a hot fire. Contact your local council for information about other disposal options. 

Biological control

The cochineal bug, (Dactylopius tomentosus 'cylindropuntia' lineage) provides control of pencil cactus and is approved for redistribution. There are several species of Dactylopius that look similar but they each control different species of cactus. 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 pencil cactus.

Chemical control

Spray actively growing plants and cover all parts of the plant with herbicide. Check treated plants and control new growth.

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: Not required when used as directed. If use is off-label check permit.
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: Not required when used as directed. If use is off-label check permit.
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 NSW 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. All species in the Cylindropuntia genus have this requirement
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. All species in the Cylindropuntia genus have this requirement except Rope pear Cylindropuntia imbricata.
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.
	*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