White weeping broom (Retama raetam)
White weeping broom is a sprawling shrub, introduced as an ornamental plant. It is now an aggressive invader of grazing lands and native vegetation in southern and western Australia, with each plant producing a large number of seeds.
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How does this weed affect you?
White weeping broom was brought to Australia as an ornamental shrub. It was first recorded in South Australia in 1841. Like many of the broom plants, it invades nutrient-poor to fertile, well-drained soils where it can fix nitrogen and form a scrub layer that can outcompete and shade out native plants. This species is possibly the most drought tolerant of the exotic brooms in Australia, making it a particular threat in dry regions and during drought years. It may infest grazing land and prevent access to stock. It is also probably the least palatable to stock of the exotic brooms.
Where is it found?
White weeping broom is native to northern Africa and western Sahara, Sicily and the Middle East. In Australia white weeping broom has become naturalised in South Australia and is growing around Perth, WA.
How does it spread?
White weeping broom reproduces from seed. Each plant produces hundreds of seed pods and up to thousands of seeds on larger plants. The seeds drop when the seed pods split open, and can be further spread by water. A hard seed coat renders most seeds dormant initially, but as the seed coat wears away germination can take place. Seeds remain viable in the soil for several years.
What does it look like?
White weeping broom is a Mediterranean shrub that grows to about 3 m tall and may reach 6 m across. Plants are grey-green with slender, drooping branches. Young plants are wispy with a single stem and strong taproot.
The leaves, which are very small (about 5 mm long) and narrow (only 1 mm wide), are quickly dropped and the plant remains leafless for most of the year.
Flowers are 8–10 mm long, white and pea-like, appearing close to the stems in clusters of 3–15. Each flower tube contains ten stamens, the pollen bearing stalks that are the male reproductive parts of the flower.
The hairless grape-shaped seed pod (10–15 mm diameter) contains one or two kidney-shaped seeds, which are about 6.5 mm long and may be yellow, green, brown or black in colour.
Stems of young plants are covered with long soft hairs but become hairless with age. An extremely similar looking and closely related species, Retama monosperma, is a popular garden plant in Australia and also a potential weed.
What type of environment does it grow in?
In its native range, white weeping broom grows in grasslands in the Mediterranean region and is a common feature of deserts and grasslands in the Sahara. White weeping broom has several adaptations, including its lack of leaves, that reduce water loss and make it ideally suited to the warm dry conditions of its native range.
Acknowledgements
CRC for Australian Weed Management: Andy Sheppard (CSIRO/Weeds CRC), John Virtue (SA DWLBC/Weeds CRC), Jason Emms (University of Adelaide/Weeds CRC), Sandy Lloyd (Agriculture WA/Weeds CRC) and John Thorp (National Weeds Management Facilitator).
More information
Control
Because there are relatively few white weeping broom infestations, and it can potentially be eradicated before it becomes established, any new outbreaks should be reported immediately to your local council weed officer. Do not try to control white weeping broom without their expert assistance. Control effort that is poorly performed or not followed up can actually help spread the weed and worsen the problem.
White weeping broom is known in Australia only from several small populations and a preferred method of control has not yet been developed. However, experience in controlling broom (Cytisus scoparius), which is a major weed in southern Australia, can be applied to this species. Any control of white weeping broom should be undertaken cooperatively with your local council.
Using herbicides
No herbicides are registered for control of white weeping broom. In the case of Cytisus scoparius, chemical control is effective in the short term but is expensive and needs to be followed up for many years until the seedbank has been depleted. There is also a risk of damage to non-target species.
Physical control
Physical removal is an option for isolated plants, especially if they have not seeded, although seedlings are hard to hand pull. Monitor the area in summer and remove any young plants that may have germinated.
Mechanical control
Bulldozing infestations into heaps and burning the resulting weed mounds has been a common method used to control broom but it only provides a temporary solution. Bulldozing causes massive soil disturbance and physical movement of plants, not only burying seeds but also spreading them beyond the original infestation. In at least one place this practice and a lack of follow-up treatments has exacerbated the Cytisus scoparius problem. Cutting stems off near the ground with saws will stress the plant but cut plants resprout vigorously, so cutting alone will not kill them. Because white weeping broom has a more continuous growth than some of the other broom species, it can be treated throughout the year whenever it is growing actively. It should be killed before it sets seed. Permits to mechanically clear vegetation may be required if native species are likely to be affected.
Fire
Fire effectively kills plants and can help to break seed dormancy. Experience using fire to control other species of broom indicates that it kills a large proportion of seeds but lightly scorched plants may resprout. Follow-up chemical treatment after fire will probably be needed for many years until the seedbank is depleted. Usually though, fire is not recommended to control broom in Australia due to the risk of out-of-control fires and because it leaves the land initially unusable, with many burnt stems remaining in the ground. Permits may be required to light fires.
Follow-up
Once an area of white weeping broom has been treated, it will be necessary to monitor the treated area for many years and destroy new plants.
Careful disposal
Hand-pulled plants can be placed into large plastic bags and left in the sun. Seeds present on pulled plants should be cut from plants, collected in bags and placed in the household rubbish. Take care not to spread seeds beyond the current infestation. If removed weed material cannot be accommodated on the site, (e.g. mulched or dried in the sun), it should be bagged and removed to tip facilities. Seeds should not be included in vegetation to be used for the production of garden compost. If the plant is being removed from gardens, dispose of waste by carefully bagging all material and putting it in the household rubbish. As seeds are difficult to destroy, it is advisable to dispose of plants when they are carrying seeds. Never give plants to other people or dump plants on vacant land, over back fences or in bushland areas. Contact your local council for specific advice before attempting to dispose of white weeping broom.
Herbicide options
WARNING - ALWAYS READ THE LABEL
Users of agricultural or veterinary chemical products must always read the label and any permit, before using the product, and strictly comply with the directions on the label and the conditions of any permit. Users are not absolved from compliance with the directions on the label or the conditions of the permit by reason of any statement made or not made in this information. To view permits or product labels go to the Australian Pesticides and Veterinary Medicines Authority website www.apvma.gov.au
Users of agricultural or veterinary chemical products must always read the label and any permit, before using the product, and strictly comply with the directions on the label and the conditions of any permit. Users are not absolved from compliance with the directions on the label or the conditions of the permit by reason of any statement made or not made in this information. To view permits or product labels go to the Australian Pesticides and Veterinary Medicines Authority website www.apvma.gov.au
See Using herbicides for more information.
PERMIT 9907 Expires 31/03/2025
Fluroxypyr 200 g/L
(Various products)
Rate: 500 mL to 1 L per 100 L water
Comments: Spot spray
Withholding period: Do not graze failed crops and treated pastures or cut for stock feed for 7 days after application. See label for further information.
Herbicide group: 4 (previously group I), Disruptors of plant cell growth (Auxin mimics)
Resistance risk: Moderate
PERMIT 9907 Expires 31/03/2025
Fluroxypyr 200 g/L
(Various products)
Rate: 35 mL per L diesel/kerosene
Comments: Basal bark
Withholding period: Do not graze failed crops and treated pastures or cut for stock feed for 7 days after application. See label for further information.
Herbicide group: 4 (previously group I), Disruptors of plant cell growth (Auxin mimics)
Resistance risk: Moderate
PERMIT 9907 Expires 31/03/2025
Fluroxypyr 333 g/L
(Starane™ Advanced)
Rate: 300 to 600 mL per 100 L water
Comments: Spot spray
Withholding period: Do not graze failed crops and treated pastures or cut for stock food for 7 days after application. See label for more information.
Herbicide group: 4 (previously group I), Disruptors of plant cell growth (Auxin mimics)
Resistance risk: Moderate
PERMIT 9907 Expires 31/03/2025
Fluroxypyr 333 g/L
(Starane™ Advanced)
Rate: 21 mL per L diesel/kerosene
Comments: Basal bark
Withholding period: Do not graze failed crops and treated pastures or cut for stock food for 7 days after application. See label for more information.
Herbicide group: 4 (previously group I), Disruptors of plant cell growth (Auxin mimics)
Resistance risk: Moderate
PERMIT 9907 Expires 31/03/2025
Glyphosate 360 g/L
(Various products)
Rate: One part product to 50 parts 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
PERMIT 9907 Expires 31/03/2025
Glyphosate 360 g/L
(Various products)
Rate: One part product to 9 parts water
Comments: Splatter gun
Withholding period: Nil.
Herbicide group: 9 (previously group M), Inhibition of 5-enolpyruvyl shikimate-3 phosphate synthase (EPSP inhibition)
Resistance risk: Moderate
PERMIT 9907 Expires 31/03/2025
Glyphosate 360 g/L
(Various products)
Rate: One part product to 20 parts water
Comments: Wipe onto leaves
Withholding period: Nil.
Herbicide group: 9 (previously group M), Inhibition of 5-enolpyruvyl shikimate-3 phosphate synthase (EPSP inhibition)
Resistance risk: Moderate
PERMIT 9907 Expires 31/03/2025
Metsulfuron-methyl 600 g/kg
(Various products)
Rate: 10 - 20 g per 100 L water plus surfactant
Comments: Spot spray
Withholding period: Nil (recommended not to graze for 7 days before treatment and for 7 days after treatment to allow adequate chemical uptake in target weeds).
Herbicide group: 2 (previously group B), Inhibition of acetolactate and/or acetohydroxyacid synthase (ALS, AHAS inhibitors)
Resistance risk: High
PERMIT 9907 Expires 31/03/2025
Metsulfuron-methyl 600 g/kg
(Various products)
Rate: 10 g per 1 L of water plus surfactant
Comments: Wipe onto leaves
Withholding period: Nil (recommended not to graze for 7 days before treatment and for 7 days after treatment to allow adequate chemical uptake in target weeds).
Herbicide group: 2 (previously group B), Inhibition of acetolactate and/or acetohydroxyacid synthase (ALS, AHAS inhibitors)
Resistance risk: High
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. |
For technical advice and assistance with identification please contact your local council weeds officer.
Reviewed 2018
