June 2011 Broomrape Orobanche spp. (O. ramosa, O. cernua var. cernua, O. aegyptiaca, O. minor)
WHAT IS IT? Broomrapes are short-lived leafless parasitic plants that grow from seed and require a host plant to survive Most are native to Europe and Asia Broomrape species of concern in South Australia are branched broomrape, Egyptian broomrape, nodding broomrape, sunflower broomrape, and clover broomrape
Note: Orobanche ramosa and O. ramosa ssp. mutelii are listed as Orobanche mutelii in the Australian Plant Census
WHY IS IT A PROBLEM? Broomrapes are amongst the world’s worst crop weeds They threaten broadleaf grain crops and vegetable industries in Australia, by reducing yields so that crops are no longer economically viable The presence of broomrape can threaten export markets
Image 18: O. aegyptiaca parasitising a carrot root. Broomrape on carrot. Dr. Reuven Jacobsohn, Agricultural Research Organisation, Bugwood.org
What are State Alert Weeds? These are invasive weeds that are not known to be in South Australia, or if present, occur in low numbers in a restricted area, and are still capable of being eradicated. An Alert Weed would pose a serious threat to the State’s primary industries, natural environments or human health if it became established here. All Alert Weeds are declared under the Natural Resources Management Act 2004: their transport and sale are prohibited (Sect. 175 and 177), plants must be destroyed (Sect. 182), and if found on your land their presence must be notified to NRM authorities (Sect. 180) – refer overleaf.
DESCRIPTION A characteristic of all broomrapes is that they have no green parts, with only the leafless flowering stem visible above ground. They are short-lived parasitic plants growing on the roots of broadleaf host plants to obtain their nutrients and water. Seeds germinate in response to host root exudates and the seedling must have contact with a host root immediately after germination to ensure its survival. Broomrape flowers. Dr. Reuven Jacobsohn, Agricultural Research Organisation, Bugwood.org HOW IT SPREADS A single plant can produce thousands of seeds per year. Seeds are released when capsules dry out and break open. Seeds, which can lay dormant in the soil for 20 years or more, are spread by flood water, vehicles, machinery, livestock, contaminated fodder and soil.
HABITAT Broomrapes thrive on poor soils in temperate and subtropical zones; Africa, Asia, Australia, New Zealand, Colombia, United States of America.
ORIGIN Broomrapes are native to Europe and Asia.
DISTRIBUTION IN AUSTRALIA O. ramosa. Photo by USDA PHIS PPQ Archive, USDA APHIS PPQ, Bugwood.org Current: Invasive broomrapes are naturalised in Western Australia, South Australia, Queensland, New South Wales, Northern Territory, Australian Orobanche spp. Capital Territory, Victoria and Tasmania.
Potential: Broomrapes can grow wherever suitable host plants are grown in temperate and subtropical climates. The regions at risk in South Australia are the irrigated areas along the Murray, and broadleaf crops in the south of the State.
HOW IT GOT HERE It is not known how broomrapes actually entered Australia. They were possibly introduced as a contaminant of imported nursery/ horticultural plants.
O. ramosa WHAT CAN YOU DO? Be on the alert for this plant using this Fact Sheet as a guide. If you see a suspicious plant that may be this State Alert Weed, please report it to your local Natural Resources Management (NRM) Board (contact details at www.nrm.sa.gov.au). For more information on weeds, including Alerts, contact your local NRM Board or visit either www.pir.sa.gov.au/biosecurity DISTRIBUTION (phone 08 8303 9620) or www.weeds.org.au.
Current distribution based on herbarium records
Potential distribution based on climate modelling
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