Privet - broad-leaf (Ligustrum lucidum)

WEED ALERT: REGIONALLY PROHIBITED WEED
If you see this plant contact your council weeds officer, the NSW Invasive Plants & Animals Enquiry Line 1800 680 244 or email weeds@dpi.nsw.gov.au

Profile

Impact

Privets are considered to be serious environmental weeds throughout Australia. Infestations threaten biodiversity, including endangered plant and animal species and ecological communities. Dense stands of privet prevent other vegetation surviving or establishing. Broad-leaf privet invades ecosystems including subtropical and coastal rainforests, rainforest margins, warm-temperate and dry rainforest, wet and dry eucalypt forests, grassy woodlands, grasslands and riparian vegetation. 

It is reported that privet pollen causes allergic reactions and hay fever. It is unlikely that the pollen of privet is strongly allergenic; however, cross-reactivity can occur where people who are sensitive to grass pollen can become sensitive to privet, producing allergic reactions. It is thought that the perfume of privet flowers causes these reactions, not the pollen. Reactions occur commonly during spring and early summer when privets produce masses of flowers and pollen. These include allergy-like symptoms such as asthma and irritation of mucous membranes. In one extreme case, hospitalisation resulting in near death occurred after the patient was exposed to privet.

Privet berries and leaves have been reported by overseas sources to be mildly toxic to humans and livestock if ingested in large amounts; however, no known cases of poisoning have occurred in Australia. 

Privets invade native and plantation forest industries, orchards and pastures in Australia. Costs of control are high and yields are reduced by the presence of privet in these production systems.

Distribution

Broad-leaf privet originates from eastern Asia. It occurs as a widespread weed in coastal and tableland areas of New South Wales.

Spread

Privet seeds are commonly spread by fruit-eating birds. Birds such as pied currawongs, silver-eyes and rosellas can spread the seed widely into previously uninfested areas. Privet seedlings often germinate in clusters, as a result of birds regurgitating the seeds. Birds and rabbits assist germination by removal of the soft coating around the seed.

Privets are also spread through the sale of garden plants from nurseries and markets, the dumping of garden waste containing seeds and the sale of foliage in floral arrangements containing fruit and seeds. Seeds can also be spread in flowing water.

Description

Broad-leaf privet grows as an evergreen shrub or small tree to a height of 4–10 m. The brown bark is covered in small white lenticels (pores that allow gas exchange).

Pointed oval-shaped leaves occur in opposite pairs, and are 4–13 cm long and 3–6 cm wide. The upper leaf surface is dark green and glossy or shiny while the under-surface is paler with distinct veins. Leaves are hairless.

Cream or white tubular flowers with four petal-like lobes occur in branched clusters – each flower is 3.5–6.0 mm long. Flowers have a sickly sweet fragrance.

Berries are 9 mm long and 12 mm in diameter, and are green when young, turning red through to blue to glossy or purplish black as they ripen. Berries usually contain two oval-shaped ribbed seeds 5 mm long. Roots are woody, branching, thickened at the crown and mostly shallow.

Habitat

Broad-leaf privets prefer warm, humid environments with moderate to high soil moisture throughout the year. Creeks, gullies and drainage lines are favoured by both species, but seedlings are able to establish in drier areas if run-off water is temporarily available. Both species occur in areas with rainfall between 700–1600 mm. Its seedlings can tolerate very low light levels, allowing them to persist beneath dense canopies of vegetation. 

Privets have been found growing in a range of soil types, from pure sands through to friable loams, and almost pure clays. However, it is generally agreed that privets thrive on more fertile shale or clay-derived soils found in riparian areas.

Acknowledgements

Authors: Elissa van Oosterhout, J. Mowatt, Leon Smith, Stephen Johnson.

Technical reviewers: Stephen Johnson, Birgitte Verbeek.

References

Hardin, D. (1992), Ligustrum vulgare L. New South Wales Flora Online, Royal Botanic Gardens and Domain Trust, Sydney.

Johnson, S. (2009), Review of the declaration of Ligustrum (privet) species in NSW, NSW Department of Primary Industries, Orange.

Johnson, S. B. (2009), ‘Privet species – are we sitting on species time bombs?’, in Proceedings of the 15th Biennial NSW Weeds Conference, Narrabri, NSW Department of Primary Industries, Orange.

back to top

Control

The following are guiding principles for privet control and management.

  • Locate, map and monitor the extent of an infestation and any changes in weediness, as well as any cultivated plants in the locality of the infestation.
  • Identify key sites, assets or industries at risk from the infestation (natural ecosystems, human health, primary production, etc.).
  • Control infestations in close proximity to the identified key sites/assets/industries, aiming to reduce weed density.
  • Prevent spread from cultivated plants in the locality.
  • Continue to control growth and spread of the infestation.

Controlling spread

Wide dispersal of seed by birds cannot be controlled; therefore controlling the spread of privet requires the removal of seed trees and young seedlings before they produce seed.

Follow up control and revegetation

Many attempts to control or remove privet have failed because of its ability to regenerate vigorously from root and stem suckers. Follow-up control measures are critical for successful removal. The removal of large numbers of privet bushes from other vegetation can cause enough disturbance that reinfestation occurs. Revegetation with appropriate species, along with ongoing weed control, can assist with preventing reinfestation. Where privet is providing a replacement habitat and food source for fruit-eating birds, control efforts must ensure that removal is undertaken gradually in combination with revegetation with suitable species.

Manual removal

Manual removal techniques such as the original ‘Bradley method’ allow for good control of privet with minimal disturbance to the surrounding vegetation. These techniques involve hand-weeding of small and medium-sized privet plants, where the gaps left by weeding must be similar to those that occur naturally after the death of a native plant. Soil disturbance should also be minimised.

Broad-leaf privet is easy to pull up when it has a stem diameter of less than 2–3 cm, particularly after rain. Similar sized small-leaf privet is more difficult to remove as the stems are more likely to break from the root system when pulled, leaving viable root segments capable of regeneration. Small-leaf privets should be dug out and the plants placed upside-down to dry out the roots.

Control with herbicides

Foliar treatments can be made to flushes of seedlings and groups of plants up to 3 m high. Plants must be actively growing, not under heat or moisture stress, and complete coverage of the foliage is necessary to ensure successful control. Foliar treatments are appropriate where infestations contain dense stands of privet and little or no other valuable vegetation.

Basal bark applications are appropriate for treating larger individual plants in amongst other vegetation. Every trunk or stem arising from the ground must be treated.

Stem injection is also appropriate for treating larger individual plants in amongst other vegetation. Stem injection has been found to be the most cost-effective method of control in terms of volume of herbicide and labour costs. It is also most effective in terms of reducing off-target herbicide damage to other vegetation.

Where is it possible or desirable to completely remove whole plants, herbicide treatment of the cut stumps must be carried out in order to prevent regrowth from stumps. Cut-stump application of herbicides is very effective for controlling young plants, suckers or regrowth.

Mechanical removal

Earth-moving machinery may be suitable for removal of dense stands of privet if high levels of soil disturbance can be tolerated. Large areas of seedlings or regrowth can be slashed. These methods will reduce the seeding capacity of a large infestation, but will not eradicate it. Follow-up with herbicide control or manual removal may provide higher levels of control. These areas should also be revegetated with trees, shrubs, ground covers or pastures and repeatedly hand-weeded or slashed thereafter. Mechanical removal is not recommended in steep areas or near water courses.

Fire

Burning is generally ineffective against privet. Privet thickets are of low flammability and bushfires do not readily move through privet-dominated vegetation. Even when fire is very intense, privets are able to regenerate rapidly by sprouting or suckering. There is evidence to suggest that both broad and small-leaf privets can recover after high intensity fires have killed the above-ground plant material (flowering has reoccurred within 3 years). Fire has been used as an initial control measure, followed up by treatment of regrowth with cut stump herbicide applications the following year. Persistent annual cool burns have been shown to eliminate small-leaf and European privet in southern USA, and it is thought that frequent fires probably assist with controlling seedling establishment of privet in infested eucalypt forests and woodlands in Australia.

Biological control

There are no introduced biological control agents available for privet control in Australia.

Reducing nutrient levels

Increased nutrient levels often contribute to the presence of privet infestations. Reducing or stopping the movement of nutrients in water from residential or industrial areas into riparian areas may help prevent establishment of large privet infestations.

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

See Using herbicides for more information.


Glyphosate 360 g/L (Roundup®)
Rate: Undiluted (1–2 mL per cut)
Comments: Stem injection technique, as per label.
Withholding period: Nil.
Herbicide group: M, Inhibitors of EPSP synthase
Resistance risk: Moderate


Metsulfuron-methyl 300 g/kg + Aminopyralid 375 g/kg (Stinger™)
Rate: 20 g per 100 L of water
Comments: Hand gun application.
Withholding period: 3 - 56 days (see label)
Herbicide group: B, Inhibitors of acetolactate synthase (ALS inhibitors) + I, Disruptors of plant cell growth (synthetic auxins)
Resistance risk: High/Moderate


Metsulfuron-methyl 600 g/kg (Brush-off®)
Rate: 10 g per 100 L of water
Comments: Apply to bushes up to 3 m high; complete coverage is essential.
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: B, Inhibitors of acetolactate synthase (ALS inhibitors)
Resistance risk: High


Metsulfuron-methyl 600 g/kg (Brush-off®)
Rate: 1 g/L + organosilicone penetrant
Comments: Gas gun / Splatter gun application. Apply only to bushes up to 3 m high when in full leaf and actively growing. Thorough coverage is essential.
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: B, Inhibitors of acetolactate synthase (ALS inhibitors)
Resistance risk: High


Picloram 44.7 g/kg + 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: I, Disruptors of plant cell growth (synthetic auxins)
Resistance risk: Moderate


Triclopyr 240 g/L + Picloram 120 g/L (Access™ )
Rate: 1.0 L per 30 L of diesel
Comments: Basal bark/cut stump application.
Withholding period: Nil
Herbicide group: I, Disruptors of plant cell growth (synthetic auxins)
Resistance risk: Moderate


Triclopyr 600 g/L (Garlon® 600)
Rate: 1.0 L per 12 L of diesel
Comments: Basal bark/cut stump application.
Withholding period: Nil.
Herbicide group: I, Disruptors of plant cell growth (synthetic auxins)
Resistance risk: Moderate


back to top

Legal requirements

The content provided here is for information purposes only and is taken from the Noxious Weeds (Weed Control) Order 2014 published in the NSW Government Gazette, detailing weeds declared noxious in New South Wales, Australia, under the Noxious Weeds Act 1993. The Order lists the weed names, the control class and the control requirements for each species declared in a Local Control Authority area.

Area Class Legal requirements
Ashfield 4 Locally Controlled Weed
The growth of the plant must be managed in a manner that continuously inhibits the ability of the plant to spread
Auburn 4 Locally Controlled Weed
The growth of the plant must be managed in a manner that continuously inhibits the ability of the plant to spread
Bankstown 4 Locally Controlled Weed
The growth of the plant must be managed in a manner that continuously inhibits the ability of the plant to spread
Blue Mountains 4 Locally Controlled Weed
The growth of the plant must be managed in a manner that continuously inhibits the ability of the plant to spread
Botany 4 Locally Controlled Weed
The growth of the plant must be managed in a manner that continuously inhibits the ability of the plant to spread
Burwood 4 Locally Controlled Weed
The growth of the plant must be managed in a manner that continuously inhibits the ability of the plant to spread
Camden 4 Locally Controlled Weed
The growth of the plant must be managed in a manner that continuously inhibits the ability of the plant to spread
Campbelltown 4 Locally Controlled Weed
The growth of the plant must be managed in a manner that continuously inhibits the ability of the plant to spread
Canada Bay 4 Locally Controlled Weed
The growth of the plant must be managed in a manner that continuously inhibits the ability of the plant to spread
Canterbury 4 Locally Controlled Weed
The growth of the plant must be managed in a manner that continuously inhibits the ability of the plant to spread
Clarence Valley 4 Locally Controlled Weed
The growth of the plant must be managed in a manner that continuously inhibits the ability of the plant to spread
Coffs Harbour 4 Locally Controlled Weed
The growth of the plant must be managed in a manner that continuously inhibits the ability of the plant to spread
Fairfield 4 Locally Controlled Weed
The growth of the plant must be managed in a manner that continuously inhibits the ability of the plant to spread
Far North Coast County Council 4 Locally Controlled Weed
The growth of the plant must be managed in a manner that continuously inhibits the ability of the plant to spread
Glen Innes Severn 4 Locally Controlled Weed
The growth of the plant must be managed in a manner that continuously inhibits the ability of the plant to spread
Gloucester 4 Locally Controlled Weed
The growth of the plant must be managed in a manner that continuously inhibits the ability of the plant to spread
Great Lakes 4 Locally Controlled Weed
The growth of the plant must be managed in a manner that continuously inhibits the ability of the plant to spread
Greater Taree 4 Locally Controlled Weed
The growth of the plant must be managed in a manner that continuously inhibits the ability of the plant to spread
Gwydir 4 Locally Controlled Weed
The growth of the plant must be managed in a manner that continuously inhibits the ability of the plant to spread
Hawkesbury River County Council 4 Locally Controlled Weed
The growth of the plant must be managed in a manner that continuously inhibits the ability of the plant to spread
Holroyd 4 Locally Controlled Weed
The growth of the plant must be managed in a manner that continuously inhibits the ability of the plant to spread
Hornsby 4 Locally Controlled Weed
The growth of the plant must be managed in a manner that continuously inhibits the ability of the plant to spread
Hunters Hill 4 Locally Controlled Weed
The growth of the plant must be managed in a manner that continuously inhibits the ability of the plant to spread
Hurstville 4 Locally Controlled Weed
The growth of the plant must be managed in a manner that continuously inhibits the ability of the plant to spread
Inverell 4 Locally Controlled Weed
The growth of the plant must be managed in a manner that continuously inhibits the ability of the plant to spread
Kempsey 4 Locally Controlled Weed
The growth of the plant must be managed in a manner that continuously inhibits the ability of the plant to spread
Kogarah 4 Locally Controlled Weed
The growth of the plant must be managed in a manner that continuously inhibits the ability of the plant to spread
Ku-ring-gai 4 Locally Controlled Weed
The growth of the plant must be managed in a manner that continuously inhibits the ability of the plant to spread
Lane Cove 4 Locally Controlled Weed
The growth of the plant must be managed in a manner that continuously inhibits the ability of the plant to spread
Leichhardt 4 Locally Controlled Weed
The growth of the plant must be managed in a manner that continuously inhibits the ability of the plant to spread
Liverpool 4 Locally Controlled Weed
The growth of the plant must be managed in a manner that continuously inhibits the ability of the plant to spread
Lockhart 4 Locally Controlled Weed
The growth of the plant must be managed in a manner that continuously inhibits the ability of the plant to spread
Lord Howe Island 2 Regionally Prohibited Weed
The plant must be eradicated from the land and that land must be kept free of the plant
Manly 4 Locally Controlled Weed
The growth of the plant must be managed in a manner that continuously inhibits the ability of the plant to spread
Marrickville 4 Locally Controlled Weed
The growth of the plant must be managed in a manner that continuously inhibits the ability of the plant to spread
Mid-Western Regional 4 Locally Controlled Weed
The growth of the plant must be managed in a manner that continuously inhibits the ability of the plant to spread
Mosman 4 Locally Controlled Weed
The growth of the plant must be managed in a manner that continuously inhibits the ability of the plant to spread
Nambucca 4 Locally Controlled Weed
The growth of the plant must be managed in a manner that continuously inhibits the ability of the plant to spread
New England Tablelands County Council 4 Locally Controlled Weed
The growth of the plant must be managed in a manner that continuously inhibits the ability of the plant to spread
North Sydney 4 Locally Controlled Weed
The growth of the plant must be managed in a manner that continuously inhibits the ability of the plant to spread
Orange 4 Locally Controlled Weed
The growth of the plant must be managed in a manner that continuously inhibits the ability of the plant to spread
Parramatta 4 Locally Controlled Weed
The growth of the plant must be managed in a manner that continuously inhibits the ability of the plant to spread
Pittwater 4 Locally Controlled Weed
The growth of the plant must be managed in a manner that continuously inhibits the ability of the plant to spread
Port Macquarie-Hastings 4 Locally Controlled Weed
The growth of the plant must be managed in a manner that continuously inhibits the ability of the plant to spread
Randwick 4 Locally Controlled Weed
The growth of the plant must be managed in a manner that continuously inhibits the ability of the plant to spread
Rockdale 4 Locally Controlled Weed
The growth of the plant must be managed in a manner that continuously inhibits the ability of the plant to spread
Ryde 4 Locally Controlled Weed
The growth of the plant must be managed in a manner that continuously inhibits the ability of the plant to spread
Shoalhaven 4 Locally Controlled Weed
The growth of the plant must be managed in a manner that continuously inhibits the ability of the plant to spread
Strathfield 4 Locally Controlled Weed
The growth of the plant must be managed in a manner that continuously inhibits the ability of the plant to spread
Sutherland 4 Locally Controlled Weed
The growth of the plant must be managed in a manner that continuously inhibits the ability of the plant to spread
Sydney 4 Locally Controlled Weed
The growth of the plant must be managed in a manner that continuously inhibits the ability of the plant to spread
Tenterfield 4 Locally Controlled Weed
The growth of the plant must be managed in a manner that continuously inhibits the ability of the plant to spread
Upper Macquarie County Council 4 Locally Controlled Weed
The growth of the plant must be managed in a manner that continuously inhibits the ability of the plant to spread
Warringah 4 Locally Controlled Weed
The growth of the plant must be managed in a manner that continuously inhibits the ability of the plant to spread
Waverley 4 Locally Controlled Weed
The growth of the plant must be managed in a manner that continuously inhibits the ability of the plant to spread
Willoughby 4 Locally Controlled Weed
The growth of the plant must be managed in a manner that continuously inhibits the ability of the plant to spread
Woollahra 4 Locally Controlled Weed
The growth of the plant must be managed in a manner that continuously inhibits the ability of the plant to spread

back to top


Broad-leaf privet
Broad-leaf privet (Photo: Elissa van Oosterhout)

Broad-leaf privet infestation.
Broad-leaf privet infestation. (Photo: Elissa van Oosterhout)

Broad-leaf privet fruit.
Broad-leaf privet fruit. (Photo: John Hosking.)

Broad-leaf privet leaves.
Broad-leaf privet leaves. (Photo: Ann Loughran.)

Broad-leaf privet flowers.
Broad-leaf privet flowers. (Photo: Elissa van Oosterhout.)

Broadleaf privet can produce many seeds which can be spread by birds.
Broadleaf privet can produce many seeds which can be spread by birds. (Photo: John Hosking.)

All privets have characteristic pore-like lenticels.
All privets have characteristic pore-like lenticels. (Photo: Birgitte Verbeek)