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Common heliotrope (Heliotropium europaeum)

Common heliotrope is a drought-hardy weed of southern Australia’s dry-land cropping regions. It is poisonous to livestock if eaten in large quantities and can reduce resources available to crops by tying up nitrogen and using soil water.

Key facts

Type: Weed, herb.

Native to: Southern and central Europe, western Asia and northern Africa.

Established in: NSW, ACT, VIC, SA, WA.

Other names: Potato Weed, Barooga Weed, Caterpillar Weed, Bishop's Beard.

Best time to act: Look for seedlings after late-spring and summer germination when moisture is sufficient and competition is low; flowering can start three to four weeks after emergence and continue through summer.

Identification

  • It is an upright annual herb that grows up to 40 cm high, with stems covered in short grey hairs.
  • Its elliptic or egg-shaped leaves are 1.5–7 cm long and 1–3 cm wide.
  • Small, trumpet-shaped flowers, up to 5 mm long, are white with a yellow throat and have five petals.
  • The fruit is a group of four brown nutlets, each containing one seed; the seeds are brownish, wrinkled or warty, and up to 2 mm long.

Where it grows

In Australia it occurs mainly in disturbed sites in the dry-land cropping areas of southern Australia, including roadsides, waste places, creek beds and poor pastures, and is absent from Tasmania.

Why it matters

  • It is poisonous to livestock, and its toxic alkaloids can cause fatalities if ingested.
  • It is one of the most abundant and common weeds of southern Australia’s grain-growing regions.
  • It ties up nitrogen and uses soil water that could otherwise be available to crops.
  • In 1985, it was estimated to infest 10 million hectares of agricultural land in Australia.

How it spreads

  • Seeds spread by water, particularly from riparian sites and steep ground where erosion and run-off occur.
  • Contaminated soil, fodder, vehicles, cultivation equipment and agricultural produce can carry seed to new sites.
  • Seeds can be picked up on the wool and hair of cattle and sheep, and spread along roadsides during maintenance work.

Control options

  • Cultivation controls seedlings, but needs to be repeated to manage successive germinations.
  • Sow competitive crop and pasture species at a suitable time to suppress regrowth; permanent pastures with good summer cover can gradually eliminate the weed.
  • Registered herbicides may be an alternative to cultivation on sites prone to soil erosion; repeated applications in pastures can make chemical control uneconomical.
  • No biological control agent is established: a trialled rust fungus had no measurable impact, and a flea beetle failed to establish.

Hygiene and washdown

  • Avoid moving potentially contaminated soil, fodder, agricultural produce or cultivation equipment between sites, as these can carry seed.
  • Check livestock wool and hair and vehicles or equipment for seeds, which can also be spread during roadside maintenance.
  • 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: Declared weed. Property managers are required by law to control declared weeds, and their import and sale are prohibited.
  • 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
  • Australian Capital Territory: Biosecurity Act 2023 (ACT), administered by ACT Biosecurity
  • 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