Green cestrum (Cestrum parqui)

Green cestrum is a large shrub with shiny leaves, clusters of yellow flowers and shiny, black berries. It is highly poisonous to cattle and can kill both animals and humans.

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How does this weed affect you?

Green cestrum:

• is toxic to animals and humans
• outcompetes other vegetation. 

Green cestrum contains a poison called ‘carboxyparquin’ that causes liver and brain damage. Bushes are still poisonous after they have been cut down or sprayed. 

Human poisoning

All parts of the plant, especially the berries, are very toxic if eaten. Eating green cestrum causes liver poisoning and can be fatal. Avoid touching the plant with bare skin.

What to do if a person is poisoned:

• 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.

Livestock poisoning

Green cestrum can cause ‘sudden death’ in livestock. Animals that appeared healthy 24 hours before will be found dead for no clear reason.  Animals that have eaten green cestrum might die in a few hours, or be sick for a few days before they die.

Signs of poisoning (before death occurs) include:

• severe stomach pain
• disorientation
• walking with a stagger
• irritability
• blood streaked manure
• diarrhoea
• weakness
• not eating
• lying on the ground
• a coma or convulsions, followed by death.

Cattle are most affected. Deaths have also occurred in goats, sheep, horses, pigs and poultry.

All parts of the plant are poisonous. Even though it is not very palatable animals may eat it when other feed is scarce. Recently sprayed, wilting plants are more palatable than healthy plants and can potentially cause more deaths.

Remove stock away from paddocks when controlling green cestrum. Do not return stock until the leaf material has disintegrated or been removed.

What does it look like?

Green cestrum is a shrub that grows 2–3 m high. It usually has many light-green, brittle stems. It sometimes grows into thickets. Established plants lose most of their leaves during winter and produce new growth in spring. 

Leaves are:

• shiny, green to dark green
• foul-smelling when crushed
• 20–30 mm wide
• 80–100 mm long
• with smooth edges
• pointed at both ends
• alternate along the branch. 

Flowers are:

• normally yellow but can be greenish
• trumpet-shaped
• with 5–7 small, triangular petals
• 20–25 mm long
• in clusters at the end of branches
• pungent smelling during the day
• sweet smelling in the evening 
• present from late spring to autumn.

Fruit are:

• shiny egg-shaped berries
• green when young
• black when ripe, though the dark pulp will stain fingers a purple colour if they are squashed
• shrivelled, dull black or grey if still on the bush in winter  
• 7–10 mm long 
• in clusters
• present during summer and autumn
• with several seeds.

Seeds are:

• wrinkled
• 3–5 mm long.

Stems are:

• light green
• brittle.

Where is it found?

Green cestrum has naturalised in eastern NSW. It grows across the eastern half of NSW, from the Victorian to the QLD borders. The worst infestations are around Sydney, Dubbo, Newcastle, Tamworth and Moree.

It was introduced from South America as an ornamental garden plant. It has become a weed in Queensland, New South Wales, Victoria and South Australia. 

What type of environment does it grow in?

Green cestrum is often found along watercourses and in gardens. It also grows on fencelines, in woodlands, grasslands and along forest edges.

It is frost tolerant and grows in a wide range of soil types and rainfall. 

Maps and records

• Recorded presence of Green cestrum during property inspections (Map: Biosecurity Information System - Weeds, 2017-2020)
  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.
  
  
• Estimated distribution of Green cestrum in NSW (Map: NSW Noxious Weed Local Control Authorities, 2010)
  Map shows weed distribution and density estimated by local council weeds officers in 2010.

How does it spread?

By seed

Birds eat the berries and spread the seed. 

By plant parts

Green cestrum will sucker if stumps are not treated after cutting. The plant will also grow from root sections which remain after a plant has been partly dug or pulled out.

More information

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Control

Successful weed control requires follow up after the initial efforts. This means looking for and killing regrowth or new seedlings. Using a combination of control methods is usually more successful.

All parts of this green cestrum are poisonous. Wear gloves and other protective clothing when handling the plant.

To tackle green cestrum:

• treat mature plants in early spring, before they flower
• control regrowth from treated plants
• look for and kill new seedlings in autumn
• be aware that control attempts can encourage seed germination
• use mulches and revegetate to suppress seedlings
• keep checking for new seedlings for many years because seeds can lie dormant. 

Early detection

Destroy new infestations before they flower and produce berries.

Competition

Planting appropriate pasture or native species can suppress seedlings and regrowth. 

Physical removal

When: Year-round. It’s easier to get the roots out of the soil after rain when the soil is moist.

Follow-up: When regrowth appears and in autumn when new seedlings appear.

Repeated cutting down, digging or pushing out by mechanical equipment will control green cestrum. Remove and destroy all the yellow roots to prevent regrowth. The roots can be burnt. In urban areas contact your local council for advice on disposal. 

Keep stock away from dead plant material as it remains poisonous. 

Chemical control

When: Early spring for mature plants, autumn for new seedlings.

Follow-up: When regrowth appears and each autumn when new seedlings appear.

Herbicides are often the most effective way to control green cestrum. Mature plants are likely to need repeated treatments.

Keep stock away from treated plants until the leaf material has disintegrated. The plants are still poisonous and the treatment makes the plant more palatable so stock are more likely to eat it. 

 

Herbicide options

See Using herbicides for more information.

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PERMIT 9907 Expires 31/03/2025
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 31/03/2025
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 30/06/2024
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 2019