Buffalo burr (Solanum rostratum)

Buffalo burr is an annual herb with bright yellow flowers and lots of hairs and prickles. It is poisonous to humans and animals and can contaminate cereal crops and wool.

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How does this weed affect you?

Buffalo burr:

• has sharp prickles that can injure people and animals
• contaminates and causes fault in wool
• competes with crops and hosts crop insect pests
• is poisonous to people and animals but is rarely eaten because of the prickles.

Human poisoning 

Buffalo burr is poisonous and there have been fatalities in children after eating the fruit.

What to do if a person is poisoned:

• If the patient is unconscious, unresponsive or having difficulty breathing dial 000 or get to the emergency section of a hospital immediately.
• If the patient is conscious and responsive call the Poisons Information Centre on 13 11 26 or your doctor.

Livestock health

Livestock losses are rare because of the prickles. There are records of pig deaths after eating the fruit. The prickles have caused injuries to livestock including to the mouth and nose.

What does it look like?

Buffalo burr is an annual herb up to 1 m tall. It is hairy and most parts are covered in prickles.

Leaves are:

• green to greyish green
• up to 10 cm long and 8 cm wide
• deeply divided with irregular rounded lobes
• hairy
• prickly along the leaf stalks and veins
• on stalks up to 5 cm long
• alternate along the stem.

Flowers are:

• bright yellow
• 3–4 cm across
• made up of 5 fused petals
• in clusters of up to 10 on short stalks
• mostly present in summer.

Fruit are:

• berries containing up to 120 seeds
• blackish when ripe
• 1 cm wide
• round or oval shaped
• enclosed in prickly, papery calyx.

 Seeds are:

• black or dark brown
• 2–3 mm wide
• wrinkled and pitted.

Stems are:

• branched
• woody when mature
• hairy
• covered in yellow prickles up to 15 mm long.

Roots

Plants have a single vertical taproot up to 1 m deep and lateral roots close to the soil surface.

Similar looking plants

Buffalo burr looks like many other Solanum plants, however apart from tomatoes (Solanum lycopersicum), it is the only yellow flowered solanum that has naturalised in Australia.

Where is it found?

In NSW, most plants have been found in the, Central Tablelands, Central West, Hunter, Northern Tablelands, North West, Riverina and Murray regions of NSW.

Buffalo burr is native to Mexico and the United States of America. It was first recorded as a weed in Australia in 1904.

What type of environment does it grow in?

Buffalo burr usually grows in semi-arid and warm temperate climates. It can grow in a wide variety of soil types. Most plants are found in cropping areas or flood plains in arid areas. It is occasionally found in pastures and along roadsides.

How does it spread?

By seed

Plants can start producing seeds as soon as 6 weeks after germinating. Each plant can produce over 1000 fruit and some plants produce over 78,000 seeds. Seed is spread:

• as a contaminant of grain crops
• by wind (sometimes parts of the plant break off and are blown like tumbleweed, spreading seeds as they move)
• in water, as the fruit can float
• by the prickly fruit sticking to clothing, animal fur or wool.

References

Lin, Y. & Tan, D.Y. (2007) The potential and exotic invasive plant: Solanum rostratum. Acta Phytotaxonomiea Sinica 45: 675-685.

PlantNET (The NSW Plant Information Network System) (2023). Solanum rostratum Dunal NSW Flora Online. Royal Botanic Gardens and Domain Trust, Sydney. Retrieved 26 January 2023 from: https://plantnet.rbgsyd.nsw.gov.au/cgi-bin/NSWfl.pl?page=nswfl&lvl=sp&name=Solanum~rostratum

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

Zhao, J., Solís-Montero, L., Lou, A. & Vallejo-Marín, M. (2013). Population structure and genetic diversity of native and invasive populations of Solanum rostratum (Solanaceae). PLoS One, 8(11), e79807.

More information

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Control

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

To manage buffalo burr control plants before flowering to prevent seeding. Check for new plants regularly as they can start producing seeds in under two months.

Wear appropriate clothing to prevent injuries from the prickles.

Physical control

Individual small plants can be dug out. 

Cultivation before fruiting can destroy the plants.

Disposal

Contact your local council for advice on how to dispose of buffalo burr.

Chemical control

Spray actively growing plants.

Herbicide options

See Using herbicides for more information.

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PERMIT 9907 Expires 31/03/2030
Glyphosate 360 g/L (Various products)
Rate: 200 mL per 10 L of water
Comments: Spot spray. Seedlings only. See permit for situations and critical comments.
Withholding period: Nil.
Herbicide group: 9 (previously group M), Inhibition of 5-enolpyruvyl shikimate-3 phosphate synthase (EPSP inhibition)
Resistance risk: Moderate

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PERMIT 12942 Expires 31/12/2030
Picloram 100 g/L + Triclopyr 300 g/L + Aminopyralid 8 g/L (Grazon® Extra)
Rate: 500 mL per 100 L of water
Comments: Spot spray. Only for urban bushland situations. See permit for critical comments.
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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2,4-D LV ester 680g/L (Estercide® Xtra)
Rate: 800 mL - 1.15 L / Ha
Comments: Use in grass pastures only. Seedling to pre-flowering. Use higher rate as plants mature.
Withholding period: Do not graze or cut for stock food for 7 days after application.
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.

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Reviewed 2025