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Starburr (Acanthospermum hispidum)

Starburr is widely naturalised in northern and eastern Australia and can spread rapidly, competing with crops, pasture and native vegetation. Its sharp, prickly burrs contaminate wool and can injure people and stock.

Key facts

Type: Weed, herb.

Native to: Central America, parts of the Caribbean and tropical South America.

Established in: QLD, NSW, WA, NT.

Other names: Goat's Head, Bristly Starburr, Upright Starburr, Hispid Starbur.

Best time to act: Look for and treat plants before they set seed, with flowering and fruiting mainly in summer–autumn and fruiting often continuing into winter.

Identification

  • An upright, branched annual herb growing up to 1 m tall, with stiff white hairs that make it rough to touch.
  • Its dull to pale yellowish green leaves are usually opposite, stalkless and up to 12.5 cm long, with irregularly toothed or lobed edges.
  • Small green to yellow flower heads are about 4–6 mm wide when flowering and 10–18 mm wide in fruit.
  • The fruits form a star-like burr with hooked prickles and two longer, spreading spines at the tip.
  • Look-alike: Paraguayan Starburr (Acanthospermum australe) is a prostrate herb with shorter leaves; its burr lacks the two spreading spines at the tip.

Where it grows

In Australia it occurs from the Kimberley through much of the Northern Territory and Queensland to north-eastern New South Wales, in disturbed places, pastures, cultivation and some grassland and woodland.

Why it matters

  • It competes with crops and pasture for space, light, water and nutrients, reducing agricultural yields and the area available for grazing; it is not grazed by stock and can impede harvesting.
  • Burrs contaminate wool and may contaminate crop and pasture seed; their sharp spines can cause discomfort, penetrate stock hooves and cause skin lesions.
  • Plants may poison stock because of their nitrate levels, and can be toxic to animals such as mice and goats when consumed daily.
  • Dense infestations in native vegetation can out-compete desirable native species and affect pasture productivity and biodiversity.

How it spreads

  • Seeds are dispersed in spiny burrs that cling to animal fur, clothing, wool bales and other fibrous materials.
  • Seeds can also travel in contaminated hay, fodder, soil, plant waste and straw, and on vehicle tyres.
  • Burrs can float and disperse downstream or in floodwaters.

Control options

  • Remove isolated plants and small populations by hand or by digging, then burn or deeply bury the material; monitor and remove new seedlings.
  • Use registered herbicides as appropriate, following product directions and checking the Australian Pesticides and Veterinary Medicines Authority for chemical information.
  • Cultivate or slash before seed set; these activities can spread the weed if done after seed set. Where cultivation is practicable, plough to bury existing seeds at least 10 cm deep and sow a suitable perennial pasture that provides dense cover and shade.
  • Prevent seed production and follow up on seedlings in newly sown pasture, as preventing seeding can eventually eliminate this annual.

Hygiene and washdown

  • Check animals moved onto a property or from infested areas and remove burrs; use only hay that is free of the weed and its seed.
  • Avoid moving contaminated soil, plant waste, straw or fodder, and check vehicle tyres for burrs before entering clean areas.
  • Inspect and clean vehicles, plant and footwear before leaving an infested area, paying attention to tyres, radiators, belly plates, tracks and floor mats.
  • Wash down at a designated bay where runoff is contained and can be monitored for seedlings.
  • Record each washdown so the client has evidence of clean entry and exit.

Classification by state

  • Australia (national): No national listing. Managed under state and territory law.
  • Queensland: Not prohibited or restricted. Not listed as prohibited or restricted matter in Queensland. Everyone must also take all reasonable and practical steps to minimise its risks (the general biosecurity obligation).
  • New South Wales: Not a priority weed. Not a state or regional priority weed in NSW. The general biosecurity duty applies: anyone dealing with it must prevent, eliminate or minimise the risk it poses.
  • Victoria: Not declared. Not declared under the Catchment and Land Protection Act 1994. Other Victorian laws may still apply.
  • South Australia: Not declared. Not declared under the Landscape South Australia Act 2019. Other laws may still apply.
  • Western Australia: Permitted, not declared. Listed as a permitted organism in WA, so it can be brought in, but it is not a declared pest.
  • Tasmania: Not declared. Not a declared weed in Tasmania. Other laws may still apply.
  • Northern Territory: Declared weed, Class B. Class B: growth and spread must be controlled. All declared weeds are also Class C, so they must not be brought into the NT.
  • Australian Capital Territory: Not declared. Not declared under the Biosecurity Act 2023 (ACT). A general biosecurity duty still applies.

Legal obligations

Every state and territory places a duty on landholders and people working on land to prevent the spread of invasive species, such as the general biosecurity obligation in Queensland and the general biosecurity duty in New South Wales. Declarations and control requirements differ between states and local government areas, so check the current official list before work starts.

  • Queensland: Biosecurity Act 2014 (Qld), administered by Biosecurity Queensland (13 25 23)
  • New South Wales: Biosecurity Act 2015 (NSW), administered by NSW Department of Primary Industries and Regional Development
  • Western Australia: Biosecurity and Agriculture Management Act 2007 (WA), administered by the WA Department of Primary Industries and Regional Development
  • Northern Territory: Territory Parks and Wildlife Conservation Act 1976 (NT), administered by NT Department of Lands, Planning and Environment

Sources