Green cestrum (Cestrum parqui)

Green cestrum is large poisonous shrub. It is a garden escape that has naturalised in north and eastern NSW.

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How does this weed affect you?

Green cestrum is a vigorous plant that can out-compete other vegetation. Green cestrum is toxic to animals including cattle, sheep, horse, pigs, poultry and humans. 

Toxicity

Green cestrum frequently causes ‘sudden death’ in livestock and is highly toxic to humans, capable of causing serious illness or death.

Although cattle are the most commonly affected animals, deaths have also occurred in goats, sheep, horses, pigs and poultry.

Green cestrum poison known as carboxyparquin causes severe liver damage and as a consequence survivors of cestrum poisoning experience elevated blood ammonia levels which then cause brain damage. Signs of poisoning in livestock include diarrhoea, abdominal pain, depression, disorientation, walking with a stagger, irritability, weakness, going off their feed, lying on the ground, and finally a period of coma or terminal convulsions.

Animals that have eaten green cestrum may die within hours or may remain sick for several days before they die. Often animals that appeared healthy 24 hours beforehand will be found dead for no apparent reason.

All parts of the plant are poisonous but as palatability is low it is not often eaten. Livestock poisoning usually occurs when other feed is scarce and animals are forced to eat cestrum, but spasmodic episodes of poisoning have been known to occur at other times.

Bushes that have been cut down or killed with herbicide will retain poison in their leaves, branches and berries. In fact, recently sprayed wilting plants are more palatable then fresh healthy plants and potentially can cause more deaths.

Livestock should always be removed from any paddock where a cestrum control program is under way and not returned until the leaf material has disintegrated or been removed.

In humans, poisoning causes liver damage, and all parts of the plant, especially the green berries are highly toxic if ingested. 

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.
• If going to a hospital take a piece of the plant for identification.

Where is it found?

Green cestrum was originally introduced into Australia from South America as an ornamental shrub for gardens. Since that time, it has become naturalised in areas of south-eastern Queensland, eastern New South Wales (NSW) and parts of Victoria and South Australia. 

In NSW, green cestrum is found in the Hunter Valley, the outer metropolitan areas of Sydney, the North Coast and the north-west, central west and south-west of the State.

Distribution map

• NSW (image)

How does it spread?

Green cestrum originally spread from gardens where it was grown as an ornamental plant. It is spread most commonly in droppings from birds that have eaten the berries. Green cestrum seeds germinate mainly in autumn with young plants taking two or more years to flower and set seed. Mature plants will flower and seed each year. Green cestrum will sucker freely from its base if stumps are not treated after cutting. The plant will also grow from sections of the fleshy root which remain after a plant has been partly dug or pulled out.

Life cycle

Green cestrum seeds germinate mainly in autumn with young plants taking two or more years to flower and set seed. Mature plants will flower and seed each year. Seeds from these plants can remain dormant in the soil for many years. Established plants are semi-deciduous, losing most of their leaves during winter and producing rapid new growth in spring. Green cestrum will sucker freely from its base if stumps are not treated after cutting. The plant will also grow from sections of the fleshy root which remain after a plant has been partly dug or pulled out.

What does it look like?

Green cestrum is a medium-sized perennial shrub growing 2–3 m. It usually has many light-green, brittle stems.

Leaves

The shiny-green leaves are 20–30 mm wide and 80–100 mm long. They have smooth edges, are pointed at each end and are arranged alternately along the branch. The leaves produce a pungent, foul smell when crushed.

Flowers

Green cestrum flowers from late spring to autumn. The flowers are normally yellow but may have a green tinge. Flowers grow in clusters at the end of branches. The flowers produce an unpleasant perfume during the day but can smell quite sweet in the evening. Individual flowers are 20–25 mm long, and are trumpet-shaped – opening into five, six or seven small, triangular lobes.

Fruit

Clusters of shiny, black, egg-shaped berries 7–10 mm long are produced during summer and autumn. The berries each contain several wrinkled seeds which are about 3–5 mm long. The dark pulp of the berries will stain fingers a purple colour if they are squashed. Berries remaining on the bush during winter will shrivel and become dull black or grey.

What type of environment does it grow in?

Green cestrum is normally found along watercourses and in non-crop areas where it usually grows in small to medium-sized thickets.

References

Griffiths N and Bourke C (2008). Green cestrum. Primefact 718. NSW DPI, Orange.  

Technical reviewers: George Wisemantel, Greater Taree County Council and Bruce Watt, Central Tablelands RLPB.

References

• Croft, D and Holding, D. (2004) A community approach: Green Cestrum. Factsheet. Cooperative Research Centre for Australian Weed Management.

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Control

Total eradication of green cestrum requires a combination of control techniques and frequent follow up work. Once a single control event occurs green cestrum can have vigorous regrowth from stumps or roots not removed or from dormant seed in the ground. Monitor control areas for regrowth and if necessary retreat the area using another form of control. New infestations should be destroyed before they flower and produce berries.

Physical control

Green cestrum can be controlled by repeated cutting down, digging or pushing out by mechanical equipment. All the yellow roots must be removed and destroyed appropriately to prevent regrowth. The roots can be burnt.

Chemical control

Herbicides are often the most effective and economical way of controlling green cestrum. However, only a registered herbicide should be used to control green cestrum infestations.

Take care not to contaminate watercourses near clumps of green cestrum. Also, ensure that spray drift does not affect desirable plants in areas being treated and that operators follow the recommended safety precautions when handling and using herbicides.

Mulch

Mulch can be used to suppress seedling growth after chemical or physical control. Mulch also retains moisture in the soil and provides protection for native plants that can be sown to replace the green cestrum plants.

Competition

After the removal of green cestrum plants, a vigorous pasture or appropriate native species should be established to compete with any green cestrum seedlings and regrowth.

Consult your local agronomist or council weeds officer for advice on suitable species and establishment methods for the situation.

 

Herbicide options

See Using herbicides for more information.

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PERMIT 9907 Expires 31/03/2020
Glyphosate 360 g/L (Roundup®)
Rate: 1 part glyphosate to 1.5 parts water
Comments: Cut, scrape and paint.
Withholding period: Nil.
Herbicide group: M, Inhibitors of EPSP synthase
Resistance risk: Moderate

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PERMIT 9907 Expires 31/03/2020
Glyphosate 360 g/L (Roundup®)
Rate: 1 part glyphosate to 50 parts water
Comments: Spot spray.
Withholding period: Nil.
Herbicide group: M, Inhibitors of EPSP synthase
Resistance risk: Moderate

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PERMIT 11427 Expires 30/06/2019
Triclopyr 600 g/L (Garlon® 600)
Rate: 1.0 L per 30 L of diesel
Comments: Basal bark application. DO NOT over treat as excessive run-off might affect adjacent trees and shrubs through root absorption.
Withholding period: Nil.
Herbicide group: I, Disruptors of plant cell growth (synthetic auxins)
Resistance risk: Moderate

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2,4-D 300 g/L + Picloram 75 g/L (Tordon® 75-D)
Rate: 650 mL per 100 L of water
Comments: Handgun application on actively growing bushes in full leaf.
Withholding period: 1-8 weeks (see label).
Herbicide group: I, Disruptors of plant cell growth (synthetic auxins)
Resistance risk: Moderate

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Amitrole 250 g/L + Ammonium thiocyanate 220 g/L (Various products)
Rate: 1.1 L per 100 L of water
Comments: Handgun application on active growth, before flowering.
Withholding period: Nil
Herbicide group: Q, Bleachers: Inhibitors of carotenoid biosynthesis unknown target
Resistance risk: Moderate

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Picloram 100 g/L + Triclopyr 300 g/L + Aminopyralid 8 g/L (Grazon Extra®)
Rate: 500 mL in 100 L of water
Comments: Apply from late spring to early autumn. Any regrowth and seedlings must be resprayed when 1 m high.
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: I, Disruptors of plant cell growth (synthetic auxins)
Resistance risk: Moderate

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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

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Triclopyr 240 g/L + Picloram 120 g/L (Access™ )
Rate: 1.0 L per 60 L of diesel
Comments: Basal bark application.
Withholding period: Nil
Herbicide group: I, Disruptors of plant cell growth (synthetic auxins)
Resistance risk: Moderate

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Triclopyr 300 g/L + Picloram 100 g/L (Grazon® DS)
Rate: 500 mL per 100 L of water
Comments: Apply from late spring to early autumn. Any regrowth and seedlings must be resprayed when 1 m high.
Withholding period: Nil.
Herbicide group: I, Disruptors of plant cell growth (synthetic auxins)
Resistance risk: Moderate

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Triclopyr 600 g/L (Garlon® 600)
Rate: 170 mL per 100 L of water
Comments: Retreat regrowth the next season.
Withholding period: Nil.
Herbicide group: I, Disruptors of plant cell growth (synthetic auxins)
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 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.
Central Tablelands	Regional Recommended Measure* Land managers should mitigate the risk of new weeds being introduced to their land. Land managers should mitigate spread from their land. The plant should not be bought, sold, grown, carried or released into the environment. Contain within riparian areas to protect grazing land that is free of green cestrum
Greater Sydney	Regional Recommended Measure* Land managers should mitigate the risk of new weeds being introduced to land used for grazing livestock. Land managers should mitigate spread from their land. Plant should not be bought, sold, grown, carried or released into the environment.
Hunter	Regional Recommended Measure* Land managers should mitigate the risk of new weeds being introduced to their land. Land managers should mitigate spread from their land. The plant should not be bought, sold, grown, carried or released into the environment. Land managers reduce impacts from the plant on priority assets.
Murray	Regional Recommended Measure* Land managers should mitigate the risk of new weeds being introduced to their land. Plant should not be bought, sold, grown, carried or released into the environment. Notify local control authority if found.
North Coast Exclusion zone: whole region excluding the core infestation area of Bellingen Shire Council, Richmond Valley Council, Ballina Shire Council, Lismore Council, Kyogle Council, Byron Shire Council and Tweed Shire Council	Regional Recommended Measure* Whole region: The plant or parts of the plant should not be traded, carried, grown or released into the environment. Exclusion zone: The plant should be eradicated from the land and the land kept free of the plant. Land managers should mitigate the risk of the plant being introduced to their land. Core infestation area: Land managers should reduce impacts from the plant on priority assets.
North West An exclusion zone is established for all lands in the region, except the core infestation area comprising the Gunnedah Shire council, Gwydir Shire council, Narrabri Shire council and Tamworth Regional council	Regional Recommended Measure* Whole of region: The plant should not be bought, sold, grown, carried or released into the environment. Exclusion zone: Land managers should mitigate the risk of new weeds being introduced to their land; land managers should mitigate spread from their land; the plant should be eradicated from the land and the land kept free of the plant. Core infestation: Land managers reduce impacts from the plant on priority assets
Northern Tablelands	Regional Recommended Measure* Land managers should mitigate the risk of new weeds being introduced to their land. Land managers should mitigate spread from their land. The plant should not be bought, sold, grown, carried or released into the environment.
	*To see the Regional Strategic Weeds Management Plans containing demonstrated outcomes that fulfill the general biosecurity duty for this weed click here

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Reviewed 2018