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Branched broomrape (Orobanche ramosa)

Branched broomrape is a serious threat to Australia’s broadleaf grain and vegetable industries, and can reduce crop yields by up to 70%. It is prohibited matter in NSW, where no infestations of prohibited broomrape species are known.

Key facts

Type: Weed, herb.

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

Established in: SA.

Other names: Broomrape.

Best time to act: Look for the briefly visible flowering stems mostly in spring, emerging about six weeks after germination.

Identification

  • It is a parasitic plant with no green parts, and remains underground until its flowering stem emerges from the soil.
  • The flowering stem can grow up to 65 cm tall and may be branched or single, with brown or straw-yellow colour and soft woolly hairs.
  • Leaves are sparse, tiny, scale-like and alternate near the base of the stem.
  • Trumpet-shaped flowers are arranged in a spike, usually with 10 to 20 flowers, and are mostly present in spring.
  • Its single-celled capsules contain hundreds of small, rough, oval seeds and dry and shatter in summer.
  • Look-alike: The native potato orchid (Gastrodia sesamoides) looks similar but grows up to 75 cm tall and has flowers that are brownish on the outside.

Where it grows

In Australia, branched broomrape attaches to the roots of broadleaf crops and native herbs; no known infestations of prohibited broomrape species are recorded in NSW.

Why it matters

  • It attaches to host roots and extracts their nutrients and water.
  • It can reduce crop yields by up to 70% and threatens export markets.
  • Crop hosts include canola, cabbage, broccoli, white mustard, tomato, potato, carrot, coriander, faba bean, lupins, chickpeas, lucerne, medics, clovers, lettuce, safflower and sunflowers.
  • It is extremely difficult to eradicate.

How it spreads

  • It grows from seed and needs a host plant to survive; one plant can produce thousands of seeds per year, which can remain dormant in soil for many years.
  • Seeds can spread in contaminated soil moved by farm machinery, vehicles, boots and livestock hooves, and can also spread by wind, floodwater, contaminated grain and hay.
  • Livestock can spread seeds in their gut or when seeds stick to their hair or wool.

Control options

  • Do not attempt to treat or dispose of the plant yourself.
  • If you see it anywhere in NSW, report it immediately to the NSW Biosecurity Helpline on 1800 680 244.
  • NSW DPIRD, Agriculture and Biosecurity, leads the initial response for treatment and disposal.
  • Contact your local council weeds officer for technical advice and identification assistance.

Hygiene and washdown

  • Avoid moving potentially contaminated soil on machinery, vehicles, boots or livestock, as these can spread seed.
  • Prevent the movement of potentially contaminated grain and hay, which can also carry seed.
  • 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: State prohibited weed. State prohibited weeds are the highest priority: the Victorian Government is responsible for eradicating them, so report any sighting to Agriculture Victoria.
  • 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: Declared pest (C1), prohibited. C1 Exclusion: to be kept out of WA, or out of the parts of WA where it is not established. Report any sighting to DPIRD. It must not be brought into WA (prohibited organism).
  • 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.

  • South Australia: Landscape South Australia Act 2019 (SA), administered by the regional landscape board

Sources