Horsetails (Equisetum species)

Horsetails are upright perennial plants with small cones at the top of the stems. They can outcompete other plants, reducing crop yields and are toxic to livestock.

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How does this weed affect you?

Horsetails are invasive weeds that:

• are toxic to animals, including livestock
• have rhizomes which form a thick mat underground that outcompete other plants 
• release chemicals that suppress the growth of other plants
• can reduce crop and orchard yields
• accumulate silica and heavy metals
• alters the water table
• are toxic to livestock.

Livestock poisoning

Horsetails are poisonous, they contain thiaminase which destroys vitamin B1 (Thiamine) in the guts of animals that eat large quantities. Horses, cattle and sheep can die within a few hours of eating substantial amounts of horsetails. Cattle and sheep are more likely to be poisoned by eating green horsetails. Horses are more likely to be poisoned if fed hay contaminated with horsetail. Symptoms include:

• weakness in the back legs
• excitable and or trembling
• rapid heartbeat
• convulsions and coma.

What does it look like?

Horsetails are perennial upright plants that do not flower but produce cones that release spores. The stems are rough and break easily at the joints. There are about 30 species of horsetail around the world. Two species are present in NSW: common horsetail and scouring horse rush.

Common horsetail

(Equisetum arvense) grows up to 80 cm tall and has many branches.

Stems:

Common horsetail has two types of stems:

• green, grooved (4–14 grooves) stems up to 80 cm tall and 1–5 mm in diameter with whorls of branches, each 5–40 cm long
• shorter (less than 30 cm and 1–3 mm in diameter) stems are unbranched, brown or whitish with fertile cones.

Leaves:

Leaves are tiny, scale-like and fused together in a whorl to form a cylindrical or cup-shaped sheath around the stem.

The leaf sheathes on branched stems are:

• made up of 6–18 green leaves
• 5–8 mm long with brown teeth 2–3 mm long.

The leaf sheaths on unbranched stems are:

• pale green or brown with darker teeth
• 9–22 mm long.

Cones are:

• green
• 1-4 cm long and up to 1 cm in diameter
• on top of the stem with pale greenish to yellow spores.

Roots are:

•  wiry, branched and extensive
• attached to hairy, dark brown or black rhizomes which can grow several metres deep and have many short, rounded tubers. 

 

Scouring rush horsetail

(Equisetum hyemale) grows up to 2 m tall and looks like miniature bamboo.

Stems are:

• green, slender and upright
• up to 1-2 m tall and up to 1.5 cm in diameter
• hollow with two rows of ridges and 22-45 grooves
• rarely branched.

Leaves:

Leaves are tiny, scale-like and fused together in a whorl to form a cylindrical sheath around the stem.

Leaf sheathes are:

• pale green or white with black teeth and sometimes have a black band at the base
• 11-22 mm long.

Cones:

• are up to 1.6 cm long and 8 mm in diameter
• grow at the top of the stems
• have a small abrupt point on the end.

Where is it found?

In NSW, most horsetails grow in the Greater Sydney region. Horsetails have also been found in the Central Tablelands, North Coast and North West regions.

Horsetails are native to Europe, Northern America and Asia. They have naturalised in New Zealand, Madagascar and parts of South America.

What type of environment does it grow in? 

Common horsetails are frost tolerant and grow in temperate climates with annual rainfall from 100 to 2000 mm. They grow best in free draining, sandy soils or silty loams, however they can grow in a wide range of soil types including low nutrient and acidic soils.

Scouring rush horsetail has infested areas below 620 m with 1100–1500 mm of rain per year.

Horsetails mostly grow in moist conditions:

• along stream banks, riverbanks and the edges of swamps and lakes
• in open woodlands
• in pastures
• along roadsides
• in urban areas.

Maps and records

• Recorded presence of Horsetails 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?

In the past, horsetails were grown and sold as ornamental plants in Australia and spread by gardeners.

By plant parts

Horsetails can grow from rhizome fragments and tubers. These can be spread by earth moving equipment, movement of contaminated soil and people dumping garden waste.

By spores

Horsetails produce spores that need prolonged periods of moist conditions to germinate. Most spores die from moisture stress.

References

Breitwieser I., Heenan P.J.; Nelson W.A., Wilton A.D. eds. (2010-2025). Flora of New Zealand Online – Weed Profiles. Retrieved 18 September 2025 from: http://www.nzflora.info.

Cody, W. J., & Wagner, V. (1981). THE BIOLOGY OF CANADIAN WEEDS.: 49. Equisetum arvense L. Canadian Journal of Plant Science, 61(1), 123-133.

CRC (2003). Weed Management Guide, Horsetails (Equisetum species). Cooperative Research Centre for Australian Weed Management and the Commonwealth Department of the Environment and Heritage.

James, T. K., & Rahman, A. (2010). Chemical control of field horsetail (Equisetum arvense). New Zealand Plant Protection, 63, 102-107.

Parsons, W.T., & Cuthbertson, E. G. (2001). Noxious weeds of Australia. 2nd edition. CSIRO publishing.

PlantNET (The NSW Plant Information Network System). Royal Botanic Gardens and Domain Trust, Sydney. Retrieved 18 September 2025 from: https://plantnet.rbgsyd.nsw.gov.au/cgi-bin/NSWfl.pl?page=nswfl&lvl=gn&name=Equisetum

More information

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Control

The plant’s extensive deep rhizomes and tubers make some control methods ineffective. Plants can regrow quickly after slashing or burning. Mechanical controls such as slashing, mowing and shallow excavating are likely to leave rhizomes in the soil, which can regrow.

By hand

This is only suitable for very small infestations. Dig out the plants and remove all plant material, including the underground rhizomes. This is easier when the soil is moist.

Excavation and burial

Deep excavation and burial of the contaminated soil is effective but is expensive and can disturb the adjacent vegetation.

Chemical control

The high silica content means that many herbicides do not penetrate the stems very well. A permit is available to use herbicides, but it is restricted to people who are employed or contracted to Local Control Authorities or the NSW government.

Contact your local council weeds officer for advice if you think you have found horsetails.

Herbicide options

See Using herbicides for more information.

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PERMIT 13917 Expires 31/05/2030
Dichlobenil 67.5 g/kg (Casoron G®)
Rate: 18 g /m2
Comments: For use by persons employed or contracted by local control authorities or NSW DPIE. Spread granules evenly over the soil of area to be treated and immediately water in after application. See permit for further critical use comments and restraints.
Withholding period: Not required when used as directed.
Herbicide group: 29 (previously group O), Inhibition of cellulose biosynthesis
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	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.
Greater Sydney The Northern Beaches Council area is classified as the core infestation area. An exclusion zone is established for the rest of the 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. 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 area: 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.
Hunter	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. This Regional Recommended Measure applies to Equisetum arvense
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 Coast	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	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.
Riverina	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. Your local biosecurity weeds officer can help to identify, advise on control, and how to remove this weed.
South East	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 2025