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Lesser broomrape (Orobanche minor)

Lesser broomrape is an introduced, leafless parasitic plant that takes water and nutrients from the roots of other plants, particularly clovers and other legumes. It can weaken host plants and reduce pasture or crop production, and its tiny seeds can make infestations difficult to contain.

Key facts

Type: Weed, herb.

Native to: Europe, North Africa and western Asia.

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

Other names: Broomrape, Small broomrape.

Best time to act: Survey in spring and summer when the flower spikes are visible, and remove plants before seed capsules mature.

Identification

  • Look for an upright, usually unbranched flower spike emerging from the ground near a host plant.
  • The stem is yellowish to brown and has small scale-like leaves rather than green foliage.
  • The flowers are tubular, usually pale cream or yellowish, and may have purple or reddish markings.
  • The plant has no green leaves and is attached underground to the roots of a host plant.
  • Look-alike: Other broomrape species can look similar; flower details may be needed to distinguish them.

Where it grows

It grows where suitable host plants occur, including grassland, pasture and disturbed ground; records in the Canberra and Southern Tablelands region include bushland and reserves such as Black Mountain, Mulligans Flat and Namadgi National Park.

Why it matters

  • It parasitises host roots and draws on the host plant's water and nutrients.
  • Infested clovers and other legumes can be weakened, with reduced growth and pasture or crop productivity.
  • Heavy infestations may seriously damage or kill host plants.

How it spreads

  • The minute seeds can be moved in contaminated soil, crop seed or fodder.
  • Vehicles, machinery, footwear and other equipment can carry seed between sites in attached soil or plant material.
  • Preventing seed production is important because seeds can persist in the soil.

Control options

  • Before seed capsules form, carefully remove the flowering parasite and, where practicable, its attachment and the affected host roots; contain and dispose of material so it cannot spread seed.
  • Use only herbicides registered for the particular site and purpose, following the label and local advice; treatment can also harm host plants.
  • Avoid or manage susceptible host plants where appropriate, and prevent surviving plants from setting seed.
  • Recheck infested and nearby areas over subsequent seasons, and contact the relevant state or territory biosecurity agency about suspected new infestations or reporting requirements.

Hygiene and washdown

  • Remove soil and plant material from boots, vehicles and machinery before leaving an infested site, and dispose of it where it cannot spread seed.
  • Avoid moving soil, seed or fodder from infested areas unless it has been appropriately checked or managed.
  • 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: Prohibited matter. It is an offence to deal with it, and you must notify NSW DPIRD as soon as you become aware of it.
  • 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: Declared weed. Property managers are required by law to control declared weeds, and their import and sale are prohibited.
  • Northern Territory: Declared weed. Weeds Australia lists it as a declared weed in the NT under the Weeds Management Act 2001. Check the NT declared weeds list for its class and what it requires.
  • 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

Sources