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Wild teasel (Dipsacus fullonum)

Wild Teasel has become an agricultural and environmental weed in south-eastern Australia. It competes with pasture plants, discourages livestock from grazing and can invade native vegetation along streams.

Key facts

Type: Weed, herb.

Native to: Europe and western Asia.

Established in: NSW, VIC, TAS.

Other names: Wild Teazel, Fuller's Teasel, Card Thistle, Venus' Basin.

Best time to act: Look for rosettes before stems develop in spring and treat at the leaf-rosette stage; plough before seed is set.

Identification

  • It is an erect, thistle-like herb that can grow to about 2 m high.
  • Young plants form a large basal rosette, with leaves up to 40–50 cm long and 9–10 cm wide.
  • Mature plants have ridged stems with small prickles and opposite stem leaves with finely toothed edges and prickles along the underside of the midrib.
  • Oval flower-heads, 2–8 cm long and 2–4 cm wide, have densely packed flowers above stiff, narrow, spiny bracts that turn upwards.
  • Look-alike: Before flowering, it may resemble other weedy herbs with large basal rosettes; prickles along the leaf midribs help identify it.
  • Look-alike: Its prickly stems may look similar to some thistles.

Where it grows

In Australia it occurs in areas receiving more than 750 mm annual rainfall, especially disturbed or neglected pastures, roadsides, and stream and lake margins, with records in New South Wales, Tasmania and Victoria and a collection in south-eastern South Australia.

Why it matters

  • Deep roots and large rosettes compete with pasture plants for moisture, nutrients and light.
  • Spines on the leaves and stems discourage livestock from grazing.
  • It can threaten native vegetation along streams and in wetlands, and dense patches may reduce food available to fauna.
  • The large basal rosette can shade nearby ground-dwelling plants.

How it spreads

  • Most seeds fall close to the parent plant, while bracts can catch on passing animals and flick seeds from bending stems.
  • Seeds can be carried as contaminants on agricultural produce, machinery and vehicles, and the spiny heads can become caught in wool.
  • Seeds float on water, allowing dispersal along streams.

Control options

  • Use registered herbicides at the leaf-rosette stage.
  • Plough before plants set seed.
  • Follow up with ploughing to kill plants resprouting from remaining roots and remove new seedlings.
  • There is currently no biological control agent for Wild Teasel available in Australia.

Hygiene and washdown

  • Seeds can be spread as contaminants on agricultural produce, machinery and vehicles, so check these for Wild Teasel seeds before moving them.
  • Check wool and other materials that may catch the spiny flower-heads.
  • 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: Not listed. Not found in the Western Australian Organism List. Check with DPIRD before moving or keeping it.
  • Tasmania: Not declared. Not a declared weed in Tasmania. Other laws may still apply.
  • Northern Territory: Not declared. Not on the NT A to Z weed list, and Weeds Australia does not list it as declared in the NT. Check the NT declared weeds list before moving or planting it.
  • 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.

  • New South Wales: Biosecurity Act 2015 (NSW), administered by NSW Department of Primary Industries and Regional Development
  • Victoria: Catchment and Land Protection Act 1994 (Vic), administered by Agriculture Victoria
  • Tasmania: Biosecurity Act 2019 (Tas), administered by Biosecurity Tasmania

Sources