Scotch broom (Cytisus scoparius subsp. scoparius)

Also known as: English broom

Scotch broom is an evergreen shrub. It competes with native plants and can alter the natural ecosystem or reduce stocking rates.

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How does this weed affect you?

Scotch broom will smother desirable vegetation which reduces pasture stocking rates. They form dense thickets which can block access by humans and stock but harbour feral animals such as rabbits, foxes and pigs.

Toxicity

Scotch broom is toxic to humans and some animals. It will cause discomfort and irritation, but is not life-threatening. The seeds and leaves are poisonous and can cause high blood pressure and nausea if ingested. If ingested in large amounts the toxins contained in scotch broom can weaken the heart. 

What to do if poisoning occurs:

• If the patient is unconscious, unresponsive or having difficulty breathing dial 000 or get to the emergency section of a hospital immediately.
• If the patient is conscious and responsive call the Poisons Information Centre on 13 11 26 or your doctor..

Where is it found?

Gorse and brooms are mostly confined to cool temperate areas of NSW, particularly the tablelands. Gorse is a problem in the south-eastern region of the state and the Blue Mountains. Some large populations of Scotch broom exist on the Barrington Tops and near Braidwood.

Maps and records

• Recorded presence of Scotch broom during property inspections (Map: Biosecurity Information System - Weeds, 2017-2024)
  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?

Originally, both gorse and brooms were planted as hedge or ornamental garden plants. Their main method of spread is now via seed by soil, water, machinery, footwear, stock and wildlife. The ability of the plants to shoot their seeds some metres away allows infestations to thicken quickly and to spread, particularly along water courses. Their pods burst open in hot weather during spring and summer, scattering seeds up to several metres from the plant. Seeds of these species have a hard coat that can delay germination for months or years, allowing large seed banks to develop. Seed can remain viable in the soil for many years.

Plants are normally at least two years of age before they are able to reproduce. Flowering mostly occurs from late winter to late spring. A second flowering may occur towards the end of summer and into autumn. Occasional flowers may be seen at other times.

Although germination and seedling establishment do occur annually, it is common for significant germination and survival events to occur in years following fire or soil disturbance.

What does it look like?

Scotch broom is an upright, evergreen shrub that grows to 4 m high but more commonly 1–2 m high. There are other species in this family that are similar in appearance and can be difficult to tell apart from the species covered here, such as flax-leaf broom (Genista linifolia) and Madeira broom (Genista stenopetala). Hybrids between the different species may also exist. Brooms are characterised by a long seed life, seedlings that take two or more years to grow to seed producing shrubs, and adult shrubs that may live for several decades. 

Its upper stems usually with five pronounced ridges and woody with numerous branches.

Leaves are shortly stalked, softly hairy with three leaflets per leaf. The middle leaflet is up to 20 mm long, other leaves are somewhat shorter. 

The flowers are yellow and pea-like. They are 2 – 2.5 cm long, occuring singly or in pairs, 

Brown to black pea-like pods have hairs that are confined to margins. Each pod is up to 7 cm long and 1.3 cm wide, it contains 5 - 22 seeds.

The seeds are yellowish-brown in colour to olive green. Oval shaped up to 4 mm long. They are smooth, rounded and slightly flattened.

What type of environment does it grow in?

Scotch brooms often become dense on river banks, forest margins, roadsides and other disturbed areas. They will also invade pastures and native vegetation. They are able to grow on a wide range of soil types and are able to flourish in areas with an annual rainfall over 500mm.

Acknowledgements

Authors: Michael Michelmore, Regional Weed Control Coordinator, Goulburn
Rachele Osmond, former Weeds Project Officer, Tamworth

The authors wish to thank the following people for their valuable input and comments. Annie Johnson; Stephen Johnson; John Hosking, NSW DPI and Jonah Gouldthorpe and Sandy Leighton Tasmania DPIW.

References

National Gorse Taskforce (2006) Gorse national best practice manual. Managing gorse (Ulex europaeus L.) in Australia. Department of Primary industries and Water, new Town, Tasmania.

CRC for australian Weed Management (2004) Weed Management Guide: Gorse (Ulex eurpaeus).

CRC for australian Weed Management (2004) Weed Management Guide: White Spanish broom (Cytisus multiflorus).

CRC for australian Weed Management (2004) Weed Management Guide: White weeping broom (Retama raetam).

Hosking, JR, Smith, JMB and Sheppard, AW (1998) Cytisus scoparius (L) Link ssp. scoparius. in, The Biology of Australian Weeds, volume 2. eds FD Panetta, RH Groves and RCH Shepherd. RG and FJ Richardson, Melbourne. pp. 77-88.

Richardson, RG and Hill, RL (1998) Ulex europaeus L. in The Biology of Australian Weeds, volume 2. eds FD Panetta, RH Groves and RCH Shepherd. RG and FJ richardson: Melbourne. Pp. 269–290.

Parsons, WT and Cuthbertson EG (2001) Noxious Weeds of Australia. Inkata Press. pp. 467-484.

More information

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Control

The control and management for gorse and brooms are similar. Management needs to address:

• Movement of seed so that new patches do not establish.
• The protection of humans and animals from damage from gorse prickles.
• The removal of sticks and stumps to allow area to be trafficable.
• Regrowth so that the plants do not re-establish.
• Seedlings so that gorse and brooms do not re-establish over time.
• Long term landuse to prevent reinfestation.

Techniques for control include fire, mechanical removal, grazing, herbicides, property hygiene and biological control. The cost of control is typically high. 

New infestations should be treated prior to plants flowering. Once plants begin to seed they are much more difficult to control and spread into other areas is more likely. While isolated patches may not seem a priority for some, they are more cost effective to control than larger patches. Any infestations left uncontrolled can lead to a rapid spread and increase in the problem. Tackle small, outlying infestations first and coordinate control with neighbours. Once established, these weeds are very difficult to eradicate. Control programs need a minimum of five years commitment, including yearly inspections to check for regeneration and regrowth, and follow-up treatment.

Integrated management

Integrated management programs are essential for long-term control. This involves using a combination of control methods to get the best possible results. Repeated removal of above-ground growth, by slashing, grazing or fire, will suppress plants but will not destroy them. Treatments that shatter the roots or herbicides that move though the plant and roots are required to kill these weeds.

Fire

Adult plants are typically not killed by burning. Fire kills above ground parts of the plant but plants regrow from the root stump. Also, fire does not kill the numerous seeds buried in the soil profile. Fire stimulates seed germination. Therefore any treatment using fire should be followed up with other treatments such as herbicide for at least five years.

These shrubs, particularly gorse, produce intense heat and flames when burnt, even in winter. There are large risks associated with the use of fire, including injury to people, property, and desirable plants and fauna. Fire can only be considered if these risks have been fully managed.

Mechanical

Hand grubbing

Plants should be removed well below the soil surface. This means of control is only appropriate for small scattered plants and seedlings and only when the ground is soft.

Mechanical slashing and grubbing

The stems of these shrubs are tough. Specialist equipment is generally used to break stems, to allow further access, and to avoid puncturing tyres. Mechanical treatments that go into the ground to shatter roots are considerably more successful than top removal treatments. The extra costs to get the job done properly are worth it. Mulchers are available that break sticks to fragments and shatter roots. Since slashers and choppers do not shatter roots, plants treated by these means will almost certainly need follow-up treatment. For long-term control, mechanical clearing should be used in combination with pasture establishment to provide competition, grazing, and herbicide treatments.

Grazing

Both sheep and goats will eat gorse and broom seedlings. Sheep will generally suppress the regrowth of gorse and broom but will have little impact on adult plants. Large numbers of goats can be used to reduce the regrowth of adult gorse and brooms. Grazing is also done in combination with burning, however sheep fleece may continue to be contaminated by charcoal for years after fire.

Property hygiene

Property hygiene is important to reduce the spread of weeds. As gorse and broom seed is easily transported in mud, thoroughly check equipment, footwear, vehicles and animals for seed and wash down before leaving infested areas. Vehicles, bush walkers and horse riders should stay on tracks to reduce the amount of seed picked up on tyres, footwear and hooves.

Biological

Biological controls are best for large infestations that will not be disturbed.

Several biocontrols have been released in NSW including:

• Scotch broom gall mite (Aceria genistae), which is currently the best biological control agent for Scotch broom. Under favourable conditions shrubs may die due to the gall mites’ impact. The effects can be limited by cooler climates.
• Twig mining moth (Leucoptera spartifoliella), which has minimal impact on Scotch broom, possibly due to parasitism.
• Scotch broom psyllid (Arytainilla spartiophila),which did not establish well and has not been seen since 2010.
• Seed beetle or bruchid beetle (Bruchidis villosus). Its impacts in Australia are not yet known but in New Zealand, it was destroying large numbers of seeds.

The Scotch broom gall mite is suitable for redistributing. Contact your local council weeds officer for information on using this biocontrol agent.

Herbicide

Herbicides are useful for both initial treatment and for treatment following other control methods. When using herbicides, it is important to follow the label recommendations. Herbicide control of gorse and broom frequently requires more than one treatment to be effective. The most appropriate applications are either foliar spray or cut stump methods. When applying foliar sprays ensure that the mixture is applied to the point of run-off over the whole plant, and use a penetrant or surfactant as directed on the herbicide label.

Herbicide options

See Using herbicides for more information.

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Glyphosate 360 g/L (Various products)
Rate: 100–130 mL per 10 L of water
Comments: Foliar spot spray application.
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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Picloram 100 g/L + Triclopyr 300 g/L + Aminopyralid 8 g/L (Grazon Extra®)
Rate: 250 or 350 mL in 100 L of water
Comments: Lower rate when actively growing mid-summer to pod formation. Higher rate for autumn-winter treatment.
Withholding period: Where product is used to control woody weeds in pastures there is a restriction of 12 weeks for use of treated pastures for making hay and silage; using hay or other plant material for compost, mulch or mushroom substrate; or using animal waste from animals grazing on treated pastures for compost, mulching, or spreading on pasture/crops.
Herbicide group: 4 (previously group I), Disruptors of plant cell growth (Auxin mimics)
Resistance risk: Moderate

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Picloram 44.7 g/L + Aminopyralid 4.47 g/L (Vigilant II ®)
Rate: Undiluted
Comments: Cut stump/stem injection application. Apply a 3–5 mm layer of gel for stems less than 20 mm. Apply 5 mm layer on stems above 20 mm .
Withholding period: Nil.
Herbicide group: 4 (previously group I), Disruptors of plant cell growth (Auxin mimics)
Resistance risk: Moderate

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Triclopyr 300 g/L + Picloram 100 g/L (Various products)
Rate: 250 or 350 mL per 100 L of water
Comments: Lower rate when actively growing mid-summer to pod formation. Higher rate for autumn-winter treatment.
Withholding period: Nil.
Herbicide group: 4 (previously group I), Disruptors of plant cell growth (Auxin mimics)
Resistance risk: Moderate

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Triclopyr 600 g/L (Garlon® 600)
Rate: 170 mL per 100 L of water
Comments: Late spring to early autumn. Actively growing bushes.
Withholding period: Nil.
Herbicide group: 4 (previously group I), Disruptors of plant cell growth (Auxin mimics)
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	Prohibition on certain dealings Must not be imported into the state, sold, bartered, exchanged or offered for sale.
Central Tablelands An exclusion zone is established for Cowra Shire Council and Mid-Western Regional Council areas. A core infestation area is established for Upper Macquarie County Council (Bathurst Regional Council, Blayney Council, Lithgow Council and Oberon Council), Orange City Council and Cabonne Council areas.	Regional Recommended Measure* (for Regional Priority - Containment) Within exclusion zone: Land managers should mitigate the risk of the plant being introduced to their land. Land managers should eradicate the plant from the land and keep the land free of the plant. A person should not deal with the plant, where dealings include but are not limited to buying, selling, growing, moving, carrying or releasing the plant. Notify local control authority if found. Within core infestation area: Land managers should mitigate the risk of the plant being introduced to their land. Land managers should mitigate spread of the plant from their land. A person should not buy, sell, move, carry or release the plant into the environment. Land managers should reduce the impact of the plant on assets of high economic, environmental and/or social value.
Greater Sydney	Regional Recommended Measure* (for Regional Priority - Asset Protection) Land managers should mitigate the risk of the plant being introduced to their land. Land managers should mitigate spread of the plant from their land. A person should not buy, sell, move, carry or release the plant into the environment.
Hunter An exclusion zone is established for all land in the region, except the core infestation which includes parts of: MidCoast Local Government Area, Upper Hunter Local Government Area.	Regional Recommended Measure* (for Regional Priority - Containment) Entire Hunter Local Land Services region: Land managers should mitigate the risk of the plant being introduced to their land. Exclusion zone: Notify local control authority if found. Land managers should eradicate the plant from the land and keep the land free of the plant. A person should not deal with the plant, where dealings include but are not limited to buying, selling, growing, moving, carrying or releasing the plant. Core infestation: Land managers should mitigate spread of the plant from their land. A person should not buy, sell, move, carry or release the plant into the environment. Land managers should reduce the impact of the plant on assets of high economic, environmental and/or social value.
Murray Core infestation: Berrigan Shire Council, Greater Hume Council, Murray River Council, Federation Council, Snowy Valleys Council. Exclusion zone: Albury City Council, Edward River Council, Murrumbidgee Council.	Regional Recommended Measure* (for Regional Priority - Containment) Within exclusion zone: Land managers should mitigate the risk of the plant being introduced to their land. Land managers should eradicate the plant from the land and keep the land free of the plant. A person should not deal with the plant, where dealings include but are not limited to buying, selling, growing, moving, carrying or releasing the plant. Notify local control authority if found. Within core infestation area: Land managers should mitigate the risk of the plant being introduced to their land. Land managers should mitigate spread of the plant from their land. A person should not buy, sell, move, carry or release the plant into the environment. Land managers should reduce the impact of the plant on assets of high economic, environmental and/or social value.
North Coast	Regional Recommended Measure* (for Regional Priority - Eradication) Land managers should mitigate the risk of the plant being introduced to their land. Land managers should eradicate the plant from the land and keep the land free of the plant. A person should not deal with the plant, where dealings include but are not limited to buying, selling, growing, moving, carrying or releasing the plant. Notify local control authority if found.
North West	Regional Recommended Measure* (for Regional Priority - Eradication) Land managers should mitigate the risk of the plant being introduced to their land. Land managers should eradicate the plant from the land and keep the land free of the plant. A person should not deal with the plant, where dealings include but are not limited to buying, selling, growing, moving, carrying or releasing the plant. Notify local control authority if found.
Northern Tablelands	Regional Recommended Measure* (for Regional Priority - Eradication) Land managers should mitigate the risk of the plant being introduced to their land. Land managers should eradicate the plant from the land and keep the land free of the plant. A person should not deal with the plant, where dealings include but are not limited to buying, selling, growing, moving, carrying or releasing the plant. Notify local control authority if found.
Riverina Core infestation areas: Snowy Valleys Council. Exclusion zone: All of Riverina except identified core infestation areas.	Regional Recommended Measure* (for Regional Priority - Containment) Within exclusion zone: Land managers should mitigate the risk of the plant being introduced to their land. Land managers should eradicate the plant from the land and keep the land free of the plant. A person should not deal with the plant, where dealings include but are not limited to buying, selling, growing, moving, carrying or releasing the plant. Notify local control authority if found. Within core infestation area: Land managers should mitigate the risk of the plant being introduced to their land. Land managers should mitigate spread of the plant from their land. A person should not buy, sell, move, carry or release the plant into the environment. Land managers should reduce the impact of the plant on assets of high economic, environmental and/or social value.
	*To see the Regional Strategic Weeds Management Plans containing demonstrated outcomes that fulfil the general biosecurity duty for this weed click here

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Reviewed 2023