Honey locust (Gleditsia triacanthos)

Honey locust is a deciduous tree up to 20 m tall with sharp spines on the trunk and branches. It grows in dense stands that outcompete native plants and pastures.

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How does this weed affect you?

Honey locust:

• outcompetes native plants
• reduces habitat for native animals
• competes with pasture plants, reducing productivity
• has long sharp spines that can injure animals and people, damage machinery and puncture tyres
• forms dense stands, particularly along waterways, preventing livestock access to water
• harbours pest animals such as foxes, cats and rabbits.

What does it look like?

Honey locust is a long-lived, spreading, deciduous tree up to 20 m tall. The spines on the trunk and stems are distinctive and may be simple or branched. They are up to 10 cm long. 

Ornamental cultivars may have bright coloured foliage such as yellow leaves.

Leaves are:

• present from spring to autumn
• up to 20 cm long, on stalks 3–5 cm long
• made up of many leaflets which may be grouped together in different arrangements:
  • divided into 5–15 pairs of leaflets
  • or they may be divided twice, firstly into 2–7 branches each with up to 30 pairs of leaflets.

The leaflets are:

• oval-shaped and finely toothed
• 10–35 mm long and 5–12 mm wide
• soft to touch.

Flowers are:

• creamy yellow or greenish with small petals (up to 6 mm long)
• grouped together in dangling clusters 5–10 cm long
• present from late spring to early summer.

Flowers may be bisexual or male and female flowers may occur on separate plants.

Seedpods are:

• brown
• 15–40 cm long, containing up to 25 seeds
• slightly crescent-shaped and flattened
• leathery
• filled with a sweet pulp around the seeds
• produced in large numbers every 1–2 years.

Seeds are:

• about 1 cm long
• oval shaped.

Stems are:

• shiny and brown when young
• grey when old with thick bark
• covered in spines which are sometimes branched.

Similar looking plants

Honey locust looks similar to mysore thorn (Caesalpinia decapetala), which has shorter pods (up to 10 cm) and more prominent larger white or yellow flowers.

Where is it found?

In NSW, plants have been found in all regions except the Western region. Most infestations are north of Sydney. 

Honey locust is native to eastern North America. It was introduced to Australia in the 1900s for cattle fodder, as a shade and ornamental tree.  

What type of environment does it grow in?

Honey locust trees grow best in subtropical and warm temperate climates, though they can tolerate cold temperatures. They prefer full sun and growth is slow in shaded areas. Honey Locust can grow in most soil types but grows best in alluvial flood plains along river systems. It is extremely drought tolerant.      

Maps and records

• Recorded presence of Honey locust 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?

By seed

Honey locust trees start producing seeds when they are 3 to 5 years old They can produce over 10,000 seeds per year and the seeds can remain viable for up to 20 years.

Seeds are spread by:

• water (the pods float)
• animals, especially cattle and horses that eat the pods and spread the seeds in their manure.

By plant parts

Honey locust also reproduces by root suckers, which means that trees can spread to form dense thickets.

References

Csurhes, S. Markula, A. (2016) Invasive plant risk assessment : Honey locust Gleditsia triacanthos. Queensland Biosecurity Department of Agriculture and Fisheries.

Identic Pty Ltd and Lucid. (2016). Weeds of Australia Factsheet: Gleditsia triacanthos L. Retrieved 26 September 2024 from: https://keyserver.lucidcentral.org/weeds/data/media/Html/gleditsia_triacanthos.htm

PlantNET (The NSW Plant Information Network System). Royal Botanic Gardens and Domain Trust, Sydney. Retrieved 26 September 2024 from: https://plantnet.rbgsyd.nsw.gov.au/cgi-bin/NSWfl.pl?page=nswfl&lvl=sp&name=Gleditsia~triacanthos

Richardson, F. J., Richardson, R. G., & Shepherd, R. C. H. (2011). Weeds of the south-east: an identification guide for Australia (No. Ed. 3). CSIRO.

More information

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Control

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

Clearing any vegetation along waterways may require consent before any work begins. Contact NSW Local Land Services for advice on the required approvals for your site.

Mechanical removal

If bulldozers are used to break honey locust trees at or above ground level the plants will regrow from stumps and roots. Deep ploughing or spot spraying is needed to treat regrowth.

Fire

For dense infestations burning may be successful if followed up by herbicide control. Burning allows access to treat the regrowth.

Chemical control

Spot spraying

Spraying is effective for seedlings and small trees up to 2 m tall. Spray actively growing plants, . covering all of the foliage evenly.

Basal barking

Measure the diameter of the stem to determine the herbicide rate. Spray or paint the herbicide mixture around the base of each stem from ground level up to 45 cm from the ground. Wet the bark to the point of runoff. Rough bark will require more herbicide than smooth or young thin bark. Do not apply to wet stems as this can repel the diesel or kerosine. 

Cut stump method

Cut trunks or stems and apply herbicide to the stump within 15 seconds of cutting.

Herbicide options

See Using herbicides for more information.

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Fluroxypyr 333 g/L (Starane™ Advanced)
Rate: 300 mL per 100L of water
Comments: Foliar application, up to 2 m in height.
Withholding period: Do not graze failed crops and treated pastures or cut for stock food for 7 days after application. See label for more information.
Herbicide group: 4 (previously group I), Disruptors of plant cell growth (Auxin mimics)
Resistance risk: Moderate

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Fluroxypyr 333 g/L (Starane™ Advanced)
Rate: 900 mL per 100 L of diesel
Comments: Basal bark application. Plants up to 10 cm basal diameter.
Withholding period: Do not graze failed crops and treated pastures or cut for stock food for 7 days after application. See label for more information.
Herbicide group: 4 (previously group I), Disruptors of plant cell growth (Auxin mimics)
Resistance risk: Moderate

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Fluroxypyr 333 g/L (Starane™ Advanced)
Rate: 1.8 L per 100 L of diesel
Comments: Basal bark application. Plants 10–20 cm basal diameter.
Withholding period: Do not graze failed crops and treated pastures or cut for stock food for 7 days after application. See label for more information.
Herbicide group: 4 (previously group I), Disruptors of plant cell growth (Auxin mimics)
Resistance risk: Moderate

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Fluroxypyr 333 g/L (Starane™ Advanced)
Rate: 3 L per 100 L of diesel
Comments: Basal bark application. Plants above 20 cm basal diameter.
Withholding period: Do not graze failed crops and treated pastures or cut for stock food for 7 days after application. See label for more information.
Herbicide group: 4 (previously group I), Disruptors of plant cell growth (Auxin mimics)
Resistance risk: Moderate

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Fluroxypyr 333 g/L (Starane™ Advanced)
Rate: 3 L per 100 L of diesel
Comments: Cut stump application.
Withholding period: Do not graze failed crops and treated pastures or cut for stock food for 7 days after application. See label for more information.
Herbicide group: 4 (previously group I), Disruptors of plant cell growth (Auxin mimics)
Resistance risk: Moderate

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Picloram 44.7 g/L + Aminopyralid 4.47 g/L (Vigilant II ®)
Rate: Undiluted
Comments: Cut the stem close to the ground (10 cm or less). Apply a 3–5 mm layer of gel onto stems less than 2 cm diameter. Apply 5 mm layer on stems above 2 cm diameter.
Withholding period: Nil.
Herbicide group: 4 (previously group I), Disruptors of plant cell growth (Auxin mimics)
Resistance risk: Moderate

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Triclopyr 240 g/L + Picloram 120 g/L (Access™ )
Rate: 1 L per 60 L of diesel (or biodiesel such as Biosafe).
Comments: Basal bark application for plants with stems less than 5 cm diameter at the base. Spray the bark around the stem from ground level to 30 cm high, wetting thoroughly to the point of runoff. Cut stump application for plants with stems over 5 cm in diameter.
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 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.
Central Tablelands Contain recorded populations across the Central Tablelands region.	Regional Recommended Measure* (for Regional Priority - Containment) Whole of region: 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. Garden varieties derived from Gleditsia triacanthos var. inermis cultivars are not included in this listing. However, if the grafted top dies then the root stock wildings should be controlled.
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 An exclusion zone is established for all land in the region, except the core infestation which includes: Lake Macquarie Local Government Area, Newcastle Local Government Area.	Regional Recommended Measure* (for Regional Priority - Containment) Entire Hunter Local Land Services region: Land managers should mitigate the risk of the plant being introduced to their land. Exclusion zone: 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. Core infestation: 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.
North Coast Exclusion (eradication) zone: Bellingen Shire LGA, Clarence Valley LGA (except Mann catchment), Coffs Harbour City LGA, Kempsey Shire LGA, Lord Howe Island, Nambucca Valley LGA, Port Macquarie-Hastings LGA. Core infestation (containment) zone: Ballina Shire LGA, Byron Shire LGA, Clarence Valley LGA (Mann catchment only), Kyogle Shire LGA, Lismore City LGA, Richmond Valley LGA, Tweed Shire LGA.	Regional Recommended Measure* (for Regional Priority - Containment) Whole of region: Land managers should mitigate the risk of the plant being introduced to their land. A person should not buy, sell, move, carry or release the plant into the environment. Exclusion zone: Notify local control authority if found. Land managers should eradicate the plant from the land and keep the land free of the plant. Core infestation: Land managers should mitigate spread of the plant from their land. Land managers should reduce the impact of the plant on assets of high economic, environmental and/or social value.
North West An exclusion zone is established for all lands in the region, except the core infestation area comprising the Gunnedah Shire council; Narrabri Shire council and Tamworth Regional council.	Regional Recommended Measure* (for Regional Priority - Containment) Whole of region: Land managers mitigate the risk of new weeds being introduced to their land. Within exclusion zone: 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. Within core infestation: 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 An exclusion zone is established for all the lands in the region, except the core infestation area comprising lands within the: • Inverell Shire Council, riparian areas of the Macintyre River, Severn River and Frazer’s Creek. • Uralla Shire Council riparian area of the Gwydir River. • Glen Innes Severn Council in the riparian area of the Mann River.	Regional Recommended Measure* (for Regional Priority - Containment) Whole of region: Land managers mitigate the risk of new weeds being introduced to their land. Within exclusion zone: 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. Within core infestation: 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.
	*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 2025