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Fierce thornapple (Datura ferox)

Fierce thornapple is an agricultural weed that competes strongly with crops and can invade native ecosystems, especially along watercourses. The whole plant is toxic to stock and people, with the seeds being the most poisonous part.

Key facts

Type: Weed, herb.

Native to: Central America, principally Mexico, and the southern United States.

Established in: QLD, NSW, ACT, VIC, TAS, SA, WA, NT.

Other names: Longspine thornapple.

Best time to act: Look for germination mainly in spring and summer and treat plants while small; flowering and fruiting occur through summer and autumn.

Identification

  • A robust, much-branched, bushy annual herb that can grow to 1 m high.
  • Its bright green leaves are broadly oval to almost triangular, with a few short lobes and blunt teeth along each margin.
  • White, trumpet-shaped flowers are borne singly in branch forks and are 40–60 mm long.
  • Its erect, egg-shaped capsules are 25–40 mm long and have 40–60 stout, thorn-like prickles, with the upper prickles generally longer.
  • The capsules open into four segments and shed numerous D-shaped, usually black seeds that are 4–4.8 mm long.
  • Look-alike: Common thornapple (Datura stramonium) also has erect capsules that split into four valves, but it has larger flowers, smaller and more numerous capsule prickles, and smaller seeds.
  • Look-alike: Other Datura species found in Australia have capsules that nod or hang down when ripe and open unevenly.

Where it grows

In Australia it occurs in disturbed, often fertile sites including crops, alluvial flats, stream banks, urban wasteland, roadsides and rail reserves, and is recorded in NSW, NT, QLD, SA, TAS, VIC and WA.

Why it matters

  • It competes strongly with many crops and may invade native ecosystems, especially along watercourses.
  • The plant is poisonous to stock because it contains toxic alkaloids, and seeds are the most poisonous part.
  • Stock are usually affected after eating contaminated hay, chaff or silage.
  • Children have been seriously poisoned, rarely fatally, after eating parts of the plant.

How it spreads

  • Seeds are often carried as contaminants of crop seed and may be transported thousands of kilometres by road or rail.
  • Seeds float and can be dispersed by water.
  • Seeds can also spread in mud attached to vehicles or machinery.

Control options

  • For small infestations, mechanically remove the plants.
  • On cropping land, large stands should be removed by ploughing or tilling the soil.
  • Follow up to remove seedlings that germinate in subsequent seasons.
  • Small plants are susceptible to herbicide, but treatment may be ineffective on mature plants; check the Australian Pesticides and Veterinary Medicines Authority for registered herbicides and chemical information.

Hygiene and washdown

  • Check vehicles and machinery for attached mud, which can carry seeds, and avoid moving contaminated mud between sites.
  • Be aware that crop seed can be contaminated with thornapple seed, and contaminated hay, chaff and silage can poison stock.
  • 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: Regionally controlled / restricted weed (varies by region). Where it is regionally controlled, landowners must take all reasonable steps to prevent its growth and spread on their land. Where it is a restricted weed, trade in it (including the plant, its seed or contaminated material) is prohibited.
  • 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: Declared weed. Property managers are required by law to control declared weeds, and their import and sale are prohibited.
  • Northern Territory: Declared weed, Class A. Class A: to be eradicated. 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
  • Australian Capital Territory: Biosecurity Act 2023 (ACT), administered by ACT Biosecurity
  • Victoria: Catchment and Land Protection Act 1994 (Vic), administered by Agriculture Victoria
  • Tasmania: Biosecurity Act 2019 (Tas), administered by Biosecurity Tasmania
  • South Australia: Landscape South Australia Act 2019 (SA), administered by the regional landscape board
  • 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