Broomrapes (Orobanche species)

Broomrapes are parasitic plants that limit the growth of broadleaf plants. Some species pose a serious threat to Australia’s broadleaf grain and vegetable industries.

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How do these weeds affect you?

Branched broomrape (Orobanche ramosa) poses the greatest threat to Australian crops. Other Orobanche species of concern which are not yet in Australia include:

• Egyptian broomrape (O. aegyptiaca) 
• nodding broomrape (O. cernua var. cernua)
• crenate broomrape (O. crenata)
• sunflower broomrape (O. cumana).

 These weeds:

• attach to the roots of broadleaf plants and extract their nutrients and water 
• can reduce crop yields by up to 70%
• threaten export markets
• are extremely difficult to eradicate. 

Crops and native herbs are host plants for branched broomrape. Crop hosts include: canola, cabbage, broccoli, white mustard, tomato, potato, carrot, coriander, faba bean, lupins, chickpeas, lucerne, medics, clovers, lettuce, safflower and sunflowers. 

There are two species of broomrapes in NSW that are not prohibited matter and have not shown any serious impacts:

• Clover broomrape, also called common broomrape (Orobanche minor), which is an introduced species, common and widely spread across southern Australia.
• Australian broomrape (Orobanche cernua var. australiana), which is a native species found in western NSW.

What does it look like?

The following description is a general genus level description.

Broomrapes are parasitic plants that do not have any green parts. They attach to the roots of their host plant and are only visible when the flowering stem emerges from the ground for a short time.   They are up to 65 cm tall. Clover broomrapes are up to 40 cm tall and the native broomrapes are up to 45 cm tall. 

Stems are:

• brown or straw-yellow
• covered with soft woolly hairs
• may be sticky
• branched or with a single stem. 

Leaves are:

• very sparse 
• tiny (up to 8 mm long) and scale-like
• alternate and at the base of the stem.

Flowers are:

• pale-blue, pinkish, violet, cream or white
• (common broomrape flowers are pale blue to whitish and native broomrape flowers are purple)
• trumpet-shaped
• up to 2.2 cm long
• arranged in a spike up the stem usually 10-20 flowers
• present mostly in spring.

Fruit:

• are single-celled capsules containing hundreds of seeds
• 8-10 mm long
• dry and shatter in summer.

Seeds are:

• black, brown, or yellowish-brown
• about 0.3 mm long
• oval shaped
• rough.

Similar looking plants

Broomrapes look similar to the native potato orchid (Gastrodia sesamoides), which is taller (up to 75 cm) and its flowers are brownish on the outside.

Where is it found?

There are no known infestations of the prohibited matter species of  broomrapes in NSW. 

Worldwide there are approximately 140 species of broomrape. Branched broomrape is native to southern Europe, western Asia and northern Africa. Five other broomrape species are major crop weeds in Africa, the Middle East, Europe, Asia and America.

Maps and records

• Recorded presence of Broomrapes during property inspections (Map: Biosecurity Information System - Weeds, 2017-2023)
  These records are made by authorised officers during property inspections under the Biosecurity Act 2015. Officers record the presence of priority weeds in their council area and provide this to the NSW Department of Primary Industries. Records reflect the presence of the weed on the date of inspection.
  
  

How does it spread?

Broomrapes are annual plants that grow from seed and require a host plant to survive. After a broomrape seed germinates, the seedling’s roots attach to the roots of a host plant and the whole broomrape plant remains underground until its flowering stems emerge (about 6 weeks after germination). Flowering and seed set occurs within 2–3 weeks. One plant can produce thousands of seeds per year which can lay dormant in the soil for many years.

Most seed spread in Australia has been in contamintated soil that has been moved via farm machinery, vehicles, boots and the hooves of livestock. Seed can also spread by wind, floodwater and in contaminated grain and hay. Livestock can move seed via their gut if the seeds are in their feed or when it sticks to their hair or wool.

References

Faithfull I & McLaren D (2004) Branched broomrape – identification: State prohibited weed. Landcare Note LC0272. State of Victoria, Department of Sustainability and Environment

Hosking JR, Sainty GR, Jacobs SWL & Dellow LL (in prep) The Australian WeedBOOK

Mohamed, K. I., & Musselman, L. J. (2008). Taxonomy of agronomically important Striga and Orobanche species. Progress on farmer training in parasitic weed management, 41(3), 7-14.

Panetta, F. D., & Lawes, R. (2007). Evaluation of the Australian branched broomrape (Orobanche ramosa) eradication program. Weed Science, 55(6), 644-651.

Prider, J., Correll, R., & Warren, P. (2012). A model for risk-based assessment of Phelipanche mutelii (branched broomrape) eradication in fields. Weed Research, 52(6), 526-534.

Secomb, N. (2006, September). Defining the distribution of branched broomrape (Orobanche ramosa L.) by tracing the movement of potential vectors for the spread of seed. In Proceedings of the fifteenth Australian weeds conference (pp. 24-28).

Virtue, J. DeDear, C. Traeger, A. Anderson, F. & Broonell, B. (2002) Potential hosts of branched broomrape (Orobanche ramosa L.) in Australia. In Proceedings of the 13th Australian Weeds Conference. CAWS.

More information

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Control

Please do not attempt to treat or dispose of this weed yourself. Report this plant if you see it anywhere in NSW by calling the helpline listed at the top of this page immediately.

NSW DPI will lead an initial response for the treatment and disposal of the plant to stop it from spreading.

Herbicide options

See Using herbicides for more information.

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Glyphosate 360 g/L (Various products)
Rate: 10 mL per 1 L water
Comments: Spot spray
Withholding period: Nil.
Herbicide group: 9 (previously group M), Inhibition of 5-enolpyruvyl shikimate-3 phosphate synthase (EPSP inhibition)
Resistance risk: Moderate

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Biosecurity duty

The content provided here is for information purposes only and is taken from the Biosecurity Act 2015 and its subordinate legislation, and the Regional Strategic Weed Management Plans (published by each Local Land Services region in NSW). It describes the state and regional priorities for weeds in New South Wales, Australia.

Area	Duty
All of NSW	General Biosecurity Duty All pest plants are regulated with a general biosecurity duty to prevent, eliminate or minimise any biosecurity risk they may pose. Any person who deals with any plant, who knows (or ought to know) of any biosecurity risk, has a duty to ensure the risk is prevented, eliminated or minimised, so far as is reasonably practicable.
All of NSW	Prohibited Matter A person who deals with prohibited matter or a carrier of prohibited matter is guilty of an offence. A person who becomes aware of or suspects the presence of prohibited matter must immediately notify the Department of Primary Industries All species of Orobanche are Prohibited Matter in NSW, except Clover broomrape, Orobanche minor and Australian broomrape, Orobanche cernua var. australiana.

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Reviewed 2020