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Geraldton carnation weed (Euphorbia terracina)

Geraldton carnation weed is an introduced plant that has become widespread in parts of southern Australia, including Western Australia. It can form dense stands that displace native plants and invade bushland, wetlands and other valued habitats.

Key facts

Type: Weed, herb.

Native to: Mediterranean region.

Established in: NSW, VIC, SA, WA.

Other names: false caper, false spurge.

Best time to act: Look for seedlings after autumn rain and treat plants before they flower and set seed, with flowering in south-west Western Australia mainly from August to November.

Identification

  • An erect or ascending, short-lived perennial herb that can grow to about 1 metre tall.
  • Stems are slender, green to reddish and release milky white sap when cut or damaged.
  • Leaves are bright green, narrow and alternate along the stems.
  • Small green to yellow-green flowers are held in cup-like structures, often in branched clusters; flowering in south-west Western Australia is mainly from August to November.
  • Fruits are smooth, three-lobed capsules that split explosively when ripe, releasing small, smooth seeds.
  • Look-alike: It can resemble common petty spurge (Euphorbia peplus), especially as a seedling or young plant.
  • Look-alike: It can also resemble sea spurge (Euphorbia paralias), particularly in coastal areas.

Where it grows

In Australia it grows on sandy, often calcareous soils in coastal areas, roadsides, disturbed ground and bushland, and can invade coastal heath, shrublands, wetlands and woodlands.

Why it matters

  • Dense stands can compete with native plants for space, light and nutrients, displacing them and hindering their recruitment.
  • It can invade intact bushland and threaten sites with significant biodiversity values, including wetlands and coastal plant communities.
  • Its toxic, caustic sap can irritate skin and cause painful inflammation if it contacts the eyes, nose or mouth.
  • The plant can be toxic to stock, although its unpalatable milky sap makes grazing less common.

How it spreads

  • Ripe capsules open explosively, scattering seed a few metres from the plant.
  • Longer-distance spread can occur in soil moved by vehicles and machinery, especially contaminated limestone or road-construction fill.
  • Seeds may also be moved by animals and by water along drains, streams and other drainage lines.

Control options

  • For small or scattered infestations, hand-remove plants with their roots before they set seed, wearing gloves, protective clothing and safety glasses to avoid the caustic sap.
  • Dispose of removed plants, especially flowering or fruiting material, so they cannot produce or spread seed; minimise soil disturbance.
  • Where hand removal is unsuitable, use only herbicides registered for the situation and apply them according to the product label, taking care to protect native vegetation.
  • Revisit treated sites to control resprouts and new seedlings, and report suspected outlying infestations to the relevant state biosecurity agency or local land manager.

Hygiene and washdown

  • Clean soil and plant material from vehicles, machinery, boots and equipment before leaving an infested site, and avoid moving contaminated soil or limestone.
  • Contain and dispose of seed-bearing plant material so it is not carried to uninfested 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: Declared plant. Depending on the declaration, it can be an offence to move it on public roads or sell it, and landowners may be required to control it on their land.
  • 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: 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
  • 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

Sources