Paterson's curse (Echium plantagineum)

Paterson’s curse is a winter annual herb. It is a major weed in winter pastures throughout southern Australia and can be a problem in areas of natural vegetation.

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How does this weed affect you?

Paterson’s curse is a winter annual herb that often becomes the dominant species in pastures. It is a prolific seeder that can produce more than 5000 seeds per plant per year. Large quantities of seeds may accumulate in the soil over several years. For example, a seedbank of up to 30 000 seeds per square metre has been reported. Seeds may remain dormant in the soil for up to five years.

Paterson’s curse is considered a weed because:

• It reduces pasture productivity and is toxic to livestock.
• It can degrade the natural environment, compromising habitat values by crowding out and suppressing native vegetation.
• Hay and grain infested with it fetch lower prices.
• It affects human health. Some people are allergic to the pollen and the rough hairy texture of the leaves and stems causes skin irritation in people having close contact with the plant.

Despite these problems, some farmers consider Paterson’s curse to be beneficial. In the drier regions of southern Australia, it is considered the salvation of grazing because it is often the only source of feed (despite being poisonous).

Pasture productivity

Paterson’s curse reduces pasture value as it out-competes the more nutritious and palatable pasture plants. The quick early growth of seedling roots allows it to out-compete pasture seedlings and better equips it to survive moisture stress, particularly after a false break. In autumn, seedlings may be so dense that they completely dominate other species. In winter, the large, broad rosette leaves shade and smother most other species. Where Paterson’s curse replaces legumes in a pasture, nitrogen fixation is reduced and soil fertility declines unless fertiliser is applied.

When Paterson’s curse flowers it is unattractive to grazing stock and after dying provides little useful fodder, resulting in lower stocking rates.

Effects on livestock

Paterson’s curse contains pyrrolizidine alkaloids. These alkaloids cause liver damage if livestock graze the weed for extended periods. Liver damage reduces livestock productivity, reduces their productive lifespan (increasing stock replacement rates) and may result in death. The damage is irreversible and cannot be treated.

It has been observed that the production of pyrrolizidine alkaloids in Paterson’s curse increases at the full flowering stage. This suggests that the weed is the most toxic to livestock if grazed while it is flowering. Further research is being conducted to confirm this trend.

Susceptibility to poisoning by Paterson’s curse varies with different livestock species. Pigs and horses are highly susceptible, cattle moderately susceptible and sheep and goats the least susceptible.Pigs and horses are non-ruminants and do not have the necessary micro-organisms in the stomach to break down the pyrrolizidine alkaloids.

Individual horses vary in their susceptibility, with some dying after a few weeks grazing Paterson’s curse. Others may graze the weed for successive seasons before signs of poisoning appear. There is usually a gradual loss of condition over four to six weeks followed by listlessness and poor appetite. Some horses show nervous signs such as head pressing, blindness and aimless walking. This is because toxins, normally removed by the liver, build up in the bloodstream and interfere with brain function. Most horses die once the illness is apparent, even after being removed from Paterson’s curse infested pasture. On post-mortem the liver appears small, firmer than normal, and fibrotic. Jaundice of the carcase and an excessive amount of yellow fluid in body cavities can also be expected.

Although pigs are highly susceptible to pyrrolizidine alkaloids, Paterson’s curse poisoning is rarely encountered in today’s intensive piggeries: it only occurs where pigs have grazing access to the weed or when they are fed grain contaminated with Paterson’s curse seed. Pigs are often found dead while others may be noticed sick for a few days before death. Signs of poisoning include loss of appetite, a swaying gait and arching of the back. Post-mortem examination shows jaundice of the carcase and an increase in yellow fluid throughout body cavities. The liver appears yellow and is firmer than normal.

Cattle are moderately susceptible to pyrrolizidine alkaloid poisoning because the rumen (first stomach) contains micro-organisms which can break down the alkaloids before they enter the liver and cause damage. However, if they are forced to graze large quantities of Paterson’s curse for long periods an ill-thrift condition due to liver damage may result. Cattle lose condition, may scour, waste away and die. On post-mortem, livers are characteristically hard, small and fibrotic.

Sheep and goats are relatively resistant to pyrrolizidine alkaloids because the rumen breaks down the alkaloids, and the alkaloids are metabolised in such a manner that products are produced that are less toxic. However, if sheep graze Paterson’s curse over several years some liver damage will occur and the damage will cause copper to accumulate in the liver. In sheep, under certain conditions, the copper is suddenly released into the bloodstream, resulting in death. This condition is called chronic copper poisoning.

Chronic copper poisoning occurs if copper levels in the liver are high and sheep are stressed, that is, by management practices such as mustering, shearing or lambing. Affected sheep usually separate from the flock, are reluctant to move, are jaundiced and show signs of respiratory distress. Death usually occurs within one to two days. If the animal lives as long as a week, recovery often occurs although the animal rarely thrives thereafter. Post-mortem examination shows jaundice of the carcase, black swollen kidneys, dark urine and an enlarged and fibrotic liver.

Increasing molybdenum in the diet appears to reduce the risk of chronic copper poisoning. Therefore the use of a molybdenum supplement may be advantageous.

Although sheep are relatively resistant to pyrrolizidine alkaloids there is a difference in breed susceptibility. Merino sheep are considered to be more resistant than British breeds and their Merino crosses. British breeds and their crosses tend to graze the plant more readily than Merinos, hence poisoning is more common in these breeds. Wethers are more resistant to poisoning than ewes; however there is wide variation between individual sheep.

Where is it found?

Paterson's curse is native to Mediterranean Europe and northern Africa. It was both accidentally and deliberately introduced to Australia in the 1850s and by 1890 it was showing potential as a major weed. Paterson’s curse now occurs in all States and Territories in Australia. However, the most serious infestations occur in pastoral regions of New South Wales, Victoria, South Australia and in the south-west region of Western Australia where a winter rainfall climate dominates.

Maps and records

• Recorded presence of Paterson's curse 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?

Paterson's curse reproduces by seed. It is commonly spread via contaminated hay and grain, livestock droppings and machinery. 

What does it look like?

Paterson’s curse is an erect herb commonly 60 cm high, but it can grow up to 150 cm.

Rosettes have green to light-green hairy, egg-shaped leaves that may grow to 30 cm long. The rosettes are stalked and have distinct, branched veins.

Stem leaves are also hairy, but are smaller and narrower than rosette leaves and are almost stem-clasping. Stems are branched, with multiple stems often arising from the plant base. All stems are covered with stiff hairs.

Flowers are mostly purple, but white, blue and pink flowering plants are sometimes found. The 2-3 cm long flowers are shaped like curved trumpets. Each flower has five stamens, two of which protrude past the end of the flower tube. Flowers generally appear from September to December.

Seeds are dark-brown to grey and have a roughened seed coat. Up to four seeds develop from each flower.

The plant has a stout taproot with numerous lateral roots.

What type of environment does it grow in?

Paterson’s curse is more common in winter-rainfall areas, however its wide tolerance of different climates and soils allows it to grow almost anywhere in Australia. In any locality the density of Paterson’s curse fluctuates widely from year to year. The plant is likely to be abundant during years when the autumn break is early. It is also likely to be abundant in paddocks that have not been cropped or grazed, or have only been lightly grazed, for several years.

Acknowledgements

Authors: Mikala Naughton former Project Officer (weeds), Orange Agricultural Institute
Jenene Kidston,  District Agronomist, Mudgee
Paul Sullivan, Coordinator, Biological Weed Control, Tamworth
Dr Chris Bourke, former Principal Research Scientist (poisonous plants), Orange Agricultural Institute

The authors would like to thank the following reviewers Royce Holtkamp, Entomologist, Tamworth and Sarah Robson, Veterinary Officer, Wagga Wagga for their comments and contributions.

More information

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Control

Prevention of spread

Preventing Paterson’s curse from spreading to uninfested areas should be given a high priority. Once it becomes established in an area it is extremely difficult to eradicate. Paterson’s curse spreads only through the movement of seeds; therefore methods which prevent seed moving to uninfested areas should be employed. Methods include:

• Feeding only hay or grain which is known to come from an uninfested source.
• If hay or grain is known to be contaminated with Paterson’s curse, only feeding it in infested areas or areas where Paterson’s curse will be easy to control when seeds germinate. Regularly check the feeding areas and treat any new infestations.
• Sowing certified seed.
• Avoiding moving stock from infested to uninfested areas.
• Quarantining stock. Paterson’s curse seeds are able to pass through stock without losing viability. Hold stock in a quarantine paddock for at least seven days if they are known to come from a Paterson’s curse-infested area or if their origin is unknown. Monitor the quarantine paddock for the weed and treat any new infestations. Remember, the roughened seedcoat of Paterson’s curse allows the seeds to be carried on the coats of stock.
• Cleaning machinery and vehicles before moving out of infested areas.
• Suppressing infestations on land adjacent to uninfested land.

Integrated weed management

Farmers battling Paterson’s curse will need to rely on an integrated approach to prevent seed set and reduce the populations in the long term. Integrated weed management involves using a combination of control methods. It has economical and environmental benefits by reducing the reliance on herbicides, reducing the risk of herbicide resistance and allowing weed management in most environments.

Integrated weed management of Paterson’s curse includes the use of several of the following control methods at the appropriate time:

• competitive crops and pastures
• grazing management
• a range of herbicide groups
• spray grazing
• biological control
• slashing
• hand weeding.

Competitive crops and pastures

Paterson’s curse is often one of the first plants to colonise bare ground. The key to preventing seedling establishment is to aim for full ground cover by using competitive crops or pastures.

Things you can do to achieve competitive crops and pastures:

• Choose crop and pasture varieties that are best suited to your climate and soil type.
• Ensure good agronomic practice such as appropriate sowing time and depth, adequate fertility and moisture at sowing.
• Apply high sowing rates for crops and pastures to achieve full ground cover quickly.
• Introduce narrow row spaces which will provide full ground cover much quicker than wide row spaces.
• Direct drill to minimise disturbance.
• Band nitrogen in crops. It is more directly available to the crop than broadcasting or undersowing.
• Include a high proportion of perennial species in your pasture mix.
• Allow pasture to set seed in the establishment year.
• Prepare paddocks for at least two years prior to sowing pasture to reduce the weed seed burden.
• Be prepared to spray weeds in a newly sown pasture.

Grazing management

Grazing can be used to manage Paterson’s curse quite effectively; it can weaken plants and prevent prolific seeding. When grazing the weed it is essential to maintain the competitive nature of the pasture. Pastures should be maintained with enough green leaf to promote good growth. This is particularly critical during autumn as high amounts of green leaf and full ground cover will reduce the establishment of Paterson’s curse seedlings.

When grazing Paterson’s curse it is essential to consider the following issues:

• Grazing should be concentrated when plants are young and continued at regular intervals during the year while the plants remain in the rosette stage.
• Grazing should be stopped once Paterson’s curse begins to flower to minimise stock poisoning.
• Pyrrolizidine alkaloids are present in Paterson’s curse during the rosette stage, albeit at lower levels. Therefore, only use sheep for a maximum of two years in a grazing management program.
• Avoid long periods of continuous heavy grazing.
• Fence off severe infestations to allow intensive management while protecting areas of productive pasture.
• Crash graze areas dominated by the weed with large numbers of stock for short periods.
• Non-pregnant, non-lactating adult Merino sheep should be used to graze Paterson’s curse.
• Do not allow horses, pigs, or cattle to graze Paterson’s curse.
• Grazing management will need to be maintained as dormant seed will allow re-establishment of Paterson’s curse.

Biological control

Seven insects that attack all stages of Paterson’s curse have been released in Australia and are established in the field except for the root hair flea beetle (Longitarsus aeneus) which was released but did not establish.

The leaf-mining moth (Dialectica scalariella) is widespread and common on Paterson’s curse and viper’s bugloss. Larvae of this moth feed within the leaves to form mines (mainly on the lower side). These mines turn to blisters as the larvae increase in size. Leaves are attacked from spring to autumn and this may reduce the competitiveness of Paterson’s curse when moths are present in high numbers. Native wasps sometimes parasitise these moths but do not appear to reduce the size of moth populations.

The second agent released was the crown weevil (Mogulones larvatus). Adult weevils emerge in spring and feed on leaves, producing circular-to-oval shaped holes before entering a summer inactive period. This inactive period is broken by decreasing number of daylight hours in late summer to early autumn. Feeding, mating and egg-laying soon commence and continue until spring. Young larvae initially feed inside leaf stalks, moving down into the root crown. Most damage is caused by larvae feeding in the crown during autumn, winter and spring. Plants under heavy attack may die before seeds can be produced. Crown weevils are established at hundreds of sites in NSW.

The root weevil (Mogulones geographicus) attacks Paterson’s curse in a similar way to the crown weevil except that root weevil larvae feed more in the tap root than the root crown. It has a similar life cycle to the crown weevil.  Root weevils are established at more than 30 sites in NSW.

Two flea beetle species have also been released. Adult Longitarsus aeneus feed on rosette leaves and larvae feed on root hairs. L. aeneus was released directly into the field but did not establish.

Adults of the other flea beetle (Longitarsus echii) emerge in winter. Adults feed on rosette leaves and larvae feed inside the main root. Flea beetles are established at more than 20 sites in NSW. Stem beetles (Phytoecia coerulescens) emerge in late spring and lay eggs that hatch a week later. Larvae feed inside larger stems and move to lower plant parts where they remain until the following spring. These beetles are cannibalistic with usually only one survivor emerging from each plant. Stem beetles have established at several sites in southern NSW.

The pollen beetle (Meligethes planiusculus) was the last of the insects to be released into the field. Eggs are laid in the terminal flower buds in spring. Larvae quickly emerge and feed on flower buds, flowers and developing seeds. After flowering finishes, the adult flower beetle remains fairly inactive through the remainder of summer, autumn and spring. Pollen beetles have established at several sites in southern NSW.

Slashing

Slashing does not kill Paterson’s curse outright but can delay and suppress flowering. Slashing forces the plant to regrow, using up reserves stored in the root system and weakening the plant.Paterson’s curse needs to be slashed regularly (fortnightly or monthly) during flowering as curse plants regrow quickly from the crown after slashing. Slashing should only be considered as a short-term control tool and should be used in combination with other control measures.

Hand weeding

Hand weeding, either by pulling Paterson’s curse plants out by hand or digging plants out using a hoe or shovel, is very effective on single plants, small patches or other situations where labour is not limiting. Paterson’s curse does not regenerate from small root segments left in the ground.

The best time to pull or hoe plants is before they begin to flower. If removal occurs after flowering has commenced, it is important that plants are removed from the site prior to the seeds dropping to the ground and that the plants are burnt so that developing seed does not replenish the soil seed bank. Viable seed is capable of developing on Paterson’s curse after plants have been pulled.

Burning

Burning will kill many Paterson’s curse seeds and stimulate others to germinate. However, follow-up treatment with cultivation or herbicides may be required. Burning is generally only a suitable control method when it can be incorporated as part of seedbed preparation for pasture or crop establishment. In established pastures, burning has a more detrimental effect on the pasture than on the weed.

Spraying Paterson’s curse

Today there is a wide range of selective herbicides available for controlling Paterson’s curse. Non-selective herbicides can also be used to spraytop the weed. Spraytopping uses low rates of non-selective herbicide to sterilise flowers and minimise seed set. It is essential to consider the following issues when deciding to use herbicides:

• The chemical sensitivities of your crop or pasture species and surrounding crops, pastures and environment. Be aware that the sensitivity of some crops and pastures may change with plant growth stage.
• The residual nature of the chemical, particularly on different soil types.
• The volatility of the chosen product.
• The weather and forecasts for the next few days.
• The keeping of all necessary records.
• Communication with your neighbours.
• The need to spray when plants are actively growing. Stresses such as drought, waterlogging, and extremely hot or cold weather can all reduce the effectiveness of spraying.
• The need to spray small, vigorously growing plants in the rosette stage. These are easiest to kill, require less chemical and avoid major competition with crops and pastures.
• The need to ensure that correct rates are applied and equipment is accurately calibrated.
• The need to read and understand the label instructions including safety precautions, chemical compatibilities, withholding periods and safe spraying conditions.

Spray-grazing

Spray-grazing is a method which combines the application of an appropriate herbicide at a reduced rate followed by a short period of intensive grazing.

Spray-grazing works because the low dose of herbicide, which by itself does not kill the weeds, causes Paterson’s curse to become more palatable to stock. Palatability increases because the sugar levels in the plants rise for a short period following spraying. The combination of spraying and grazing provides a severe stress which kills the plant. If Paterson’s curse is not heavily grazed, most plants will recover from the low dose of herbicide applied within three weeks. Additional benefits include minimal effect on clovers and grasses by the use of a selective herbicide, reduced herbicide cost and improved pasture productivity.

Spray-grazing is most successful in light to medium infestations where pasture has the potential to compete with and replace Paterson’s curse. Actively growing Paterson’s curse plants are sprayed six to eight weeks after germination. When the grazing withholding period has elapsed stock are introduced at five to 10 times the normal stocking rate. Non-pregnant, non-lactating adult Merino sheep should be used. Individual sheep should only be used for a maximum of two years in a spray-graze management program. Heavy grazing should continue until the Paterson’s curse has been satisfactorily reduced, but before pasture survival is threatened. Remove stock and allow the pasture to recover. Normal grazing can then resume. The spray-grazing program will need to be repeated each year until the dormant weed seed bank is exhausted.

Herbicide options

See Using herbicides for more information.

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2,4-D 300 g/L + Picloram 75 g/L (Tordon® 75-D)
Rate: 150 mL in 100 L of water
Comments: Spot spray. Rosettes to pre-flowering.
Withholding period: Do not graze or cut crops (except sugar cane 8 weeks) or pastures for stock food for 7 days after application.
Herbicide group: 4 (previously group I), Disruptors of plant cell growth (Auxin mimics)
Resistance risk: Moderate

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2,4-D amine 625 g/L (Various products)
Rate: 170–220 mL in 150 L of water
Comments: Spot spray. Young rosettes.
Withholding period: 7 days withholding for grazing
Herbicide group: 4 (previously group I), Disruptors of plant cell growth (Auxin mimics)
Resistance risk: Moderate

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2,4-D amine 625 g/L (Various products)
Rate: 1.7–2.2 L/ha
Comments: Boom spray.
Withholding period: 7 days withholding for grazing
Herbicide group: 4 (previously group I), Disruptors of plant cell growth (Auxin mimics)
Resistance risk: Moderate

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Dicamba 750 g/L (Kamba® 750)
Rate: 185 mL/100L of water. Add an activator.
Comments: Spot spray before flowering. For non crop areas.
Withholding period: Do not harvest, graze or cut for stock food for 7 days after application.
Herbicide group: 4 (previously group I), Disruptors of plant cell growth (Auxin mimics)
Resistance risk: Moderate

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Dicamba 750 g/L (Kamba® 750)
Rate: 2.7 L/ha Use a minimum of 1500 L/ha water carrier. Add an activator.
Comments: Boom spray for non-crop situations. Spray prior to flowering.
Withholding period: Do not harvest, graze or cut for stock food for 7 days after application.
Herbicide group: 4 (previously group I), Disruptors of plant cell growth (Auxin mimics)
Resistance risk: Moderate

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Glyphosate 360 g/L (Various products)
Rate: 500–700 mL /100 L of water
Comments: Spot spray actively growing plants. Use the lower rate on weeds up to 15cm tall; increase to the higher rate where weeds are over 15cm tall
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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Glyphosate 360 g/L (Various products)
Rate: 2.0–3.0 L/ha. Use 75-200 L of solution/ha
Comments: Boom application when plants are actively growing. Use the lower rate on weeds up to 15cm tall; increase to the higher rate where weeds are over 15cm tall.
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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MCPA 500 g/L (Various products)
Rate: 1.0–1.5 L/ha
Comments: Apply at early rosette stage
Withholding period: Do not graze or cut for stock food for 7 days after application.
Herbicide group: 4 (previously group I), Disruptors of plant cell growth (Auxin mimics)
Resistance risk: Moderate

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Metsulfuron-methyl 300 g/kg + Aminopyralid 375 g/kg (Various products)
Rate: 10 g per 100 L of water (always add a Wetter 100 mL/100L)
Comments: Spray with a hand gun. Adjuvant: Wetter 1000g/L non-ionic alcohol alkoxylate (TITAN WETTER 1000 or BS1000 or equivalent).
Withholding period: Pastures - Grazing for meat production or cutting for animal feed: Do not graze for 56 days after application. See label for further details
Herbicide group: 2 (previously group B), Inhibition of acetolactate and/or acetohydroxyacid synthase (ALS, AHAS inhibitors) + 4 (previously group I), Disruptors of plant cell growth (Auxin mimics)
Resistance risk: High/Moderate

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Metsulfuron-methyl 600 g/kg (Various products)
Rate: 5 g in 100 L of water
Comments: Apply to rosettes after full leaf expansion but before head emergence. Do not spray after emergence of first flowers, as seed set has occurred.
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

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Metsulfuron-methyl 600 g/kg (Various products)
Rate: 15 g/ha
Comments: Boom spray. Apply to rosettes after full leaf expansion but before head emergence. Do not spray after emergence of first flowers, as seed set has occurred.
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

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Picloram 100 g/L + Triclopyr 300 g/L + Aminopyralid 8 g/L (Grazon Extra®)
Rate: 250 mL in 100 L of water
Comments: Spot spray from rosette to flowering plants
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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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.
Hunter An exclusion zone is established for all land in the region, except the core infestation which includes parts of: Dungog Local Government Area, Maitland Local Government Area, Muswellbrook Local Government Area, Singleton 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.
	*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