Bracken fern (Pteridium esculentum)

Also known as: bracken

Bracken fern is a native fern that can grow up to 2 m tall. It competes with pastures and is poisonous to livestock.

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How does this weed affect you?

Bracken fern is a native plant, but it is a weed in grazing land and pine forests. It:

• forms dense stands and competes with pastures
• is poisonous to people and livestock
• accumulates mulch from dead fronds that prevent other plants germinating
• regenerates after fire and dominates recently burned areas
• provides shelter for pest animals including pigs, foxes and rabbits.

Livestock poisoning

All parts of the plant are toxic. Bracken contains two types of toxins that affect livestock:

1) Fern norsesquiterpene glycosides, which mainly affect cattle. The young curled up fronds contain the highest level of toxin. This toxin causes:

• ‘bracken poisoning’, usually in calves that have eaten lots of bracken over two to four weeks. It causes internal bleeding and visible symptoms of blood in the dung, urine and mucus.
• bladder cancer, usually only in cattle over three years old that have eaten small quantities over several years. Symptoms include blood tinged urine and pale gums.

2) Thiaminase which mainly affects horses and pigs. Fronds and rhizomes contain this toxin. Symptoms in horses include loss of coordination, appetite and holding the head low. Symptoms in pigs include loss of appetite and listlessness.

Human poisoning

Eating the young fronds can cause cancer of the digestive tract. Drinking untreated milk from cows that have grazed large amounts of bracken may cause stomach cancer.

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.

What does it look like?

Bracken is a fern, so it has fronds rather than leaves and does not produce flowers or seeds. Ferns grow from spores which are produced in sori on the underside of the fronds. Established bracken stands usually have a mixture of green and dead fronds. Dead fronds can stay standing for several years.

Fronds:

The fronds are divided and subdivided into many lobes. The fronds appear in spring and die in autumn in temperate climates but may live for up to two years in milder climates.

Mature fronds are:

• upright, stiff and leathery
• dark emerald green on top and paler underneath
• usually 0.6-1.5 m long
• smooth on top with fine hairs underneath.

The sori which contain spores are rare but can be found along the edges on the undersides of the fronds. They often form a continous line.

Young fronds are:

• tightly coiled when first emerging
• bright green and soft when unfurled
• harder and darker as they expand.

Roots:

The roots are extensive and dense. The rhizomes are:

• 2-10 mm in diameter
• several metres long
• densely covered with dark, red-brown hairs.

Where is it found?

Bracken fern is native to Australia. In NSW it grows in coastal areas, on the tablelands and sometimes on the western slopes.

What type of environment does it grow in?

Bracken fern grows in temperate and subtropical areas of NSW especially along the coast. High rainfall areas in open forests and woodlands are its natural habitat. It has become invasive in pastures, especially overgrazed or degraded pastures, pine forests, along roadsides, fence lines and railway lines, and on industrial sites.

How does it spread?

By spores

Bracken fern produces spores that are usually dispersed in late summer to autumn. This can vary in different years and across different locations. Spores are spread by the wind and germinate in moist, sheltered situations.

By plant parts

Rhizomes spread out from a parent plant when new shoots grow up from the rhizomes. Infestations thicken and grow larger over time. Machinery can carry rhizomes to new areas.

References

DPIPWE (1999). Bracken (Pteridium esculentum), SS 125. Tasmanian Department of Primary Industries, Parks, Water and Environment, Hobart.

Everist, S.L. (1974). Poisonous plants of Australia. Angus and Robertson, Sydney.

McKenzie, R. (2020). Australia's poisonous plants, fungi and cyanobacteria: A guide to species of medical and veterinary importance. CSIRO PUBLISHING.

McWhirter, L. & Kemp, H. (2010). PRIMEFACT: No 730 Bracken fern. NSW DPI.

PlantNET (The NSW Plant Information Network System). Royal Botanic Gardens and Domain Trust, Sydney. Retrieved 20 February 2020 from: https://plantnet.rbgsyd.nsw.gov.au/cgi-bin/NSWfl.pl?page=nswfl&lvl=sp&name=Pteridium~esculentum

Robinson, L. (1991). Field guide to the native plants of Sydney. Kangaroo Press, Kenthurst NSW.

More information

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Control

Successful weed control relies on follow up after the initial efforts. This means looking for and killing regrowth or new plants. Using a combination of control methods is usually more successful.. Regrowth from rhizomes makes bracken persistent.

To tackle bracken fern:

• be persistent, regrowth can occur from all control methods
• reduce the bulk of infestations
• suppress new growth to exhaust the rhizomes.

Prevention

Clean cultivation equipment after use near bracken fern\.

Pasture management

Pasture improvement can be used to outcompete bracken fern. If sowing pasture, choose species or varieties of grasses and legumes that will be suited to the soil type and climate of the area. Consult your local agronomist for recommendations. To maintain healthy pastures:

• grow combinations of winter and summer pastures
• rest pastures between grazing periods
• test soil to check fertility and pH and use fertiliser or lime if needed.

Cultivation

Combining cultivation over two or three consecutive years with cropping before the establishment of a competitive pasture helps control bracken. Cultivate in summer to 15-20 cm deep. This will break up the rhizomes and bring them up to the surface to dry out and die. Tined implements are best for dragging the rhizomes to the surface. Disc ploughs and rotary hoes can also work. Slash or burn thick infestations before cultivating to avoid damaging machinery. 

Do not cultivate steep country with shallow soils.

Slashing

When: In late spring or early summer when new fronds have just unfurled.

Follow up: Slash again 4 weeks after the first cut and again four weeks after that.

Best results are from 3 cuts per year from late spring/ early summer to late summer/ early autumn. Repeated slashing can eventually control bracken, but it needs to be done for a minimum of three consecutive years.  This method is not suitable for steep or rocky country.

Rolling

Rollers crush and bruise the fronds but are less effective than cutting. As with slashing, repeated crushing of the fronds may eventually wear down the energy reserves in the rhizome.

Using a roller is a quicker, more versatile and less expensive method than either slashing or cultivation. Rollers with a ribbed or irregular surface are best.

Fire

When: In winter.

Follow up: With other control methods.

Fire is not an effective control technique on its own. Bracken regenerates after burning because fire does not damage the rhizomes. Burning can be used to reduce the amount of dead fronds in winter and to improve herbicide application or cultivation. New fronds have high levels of toxins so ensure burnt paddocks are not grazed when fronds regrow.

Chemical control

Spraying

When: Late spring to late autumn when most fronds are fully unfurled.

Follow up: Wait at least 6 months before grazing or using any follow up controls because sprayed plants may take a number of months to die off.

Do not cut or roll bracken for at least 8-12 months before chemical controls. 

Use recommended spray adjuvants to help the chemical to penetrate the leaves. Herbicide is most effective in late autumn. No herbicide will provide complete control with a single application.

Animals can still be at risk of poisoning if they graze bracken even if it has been treated by herbicide.

Herbicides can be used effectively as part of a pasture re-sowing strategy. Slash bracken in winter/spring and then apply herbicide in the following autumn to fully expanded fronds. Remember to leave at least 8 months from slashing to herbicide application to allow time for regrowth. Results may not be visible until the next season and then a follow-up application is recommended on any new fronds that have emerged.

Herbicide options

See Using herbicides for more information.

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Glyphosate 360 g/L (Various products)
Rate: 1.5 L per 100 L of water
Comments: Spot spray application. Apply during autumn at full frond expansion, while plants are actively growing. Repeat treatments necessary. Add surfactant.
Withholding period: Nil.
Herbicide group: M, Inhibitors of EPSP synthase
Resistance risk: Moderate

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Glyphosate 360 g/L (Various products)
Rate: 9.0 L/ha
Comments: Boom spray application. Apply during autumn at full frond expansion, while plants are actively growing. Repeat treatments necessary. Add surfactant.
Withholding period: Nil.
Herbicide group: M, Inhibitors of EPSP synthase
Resistance risk: Moderate

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Glyphosate 360 g/L (Various products)
Rate: 1 L in 2 L of water
Comments: Wiper application
Withholding period: Nil.
Herbicide group: M, Inhibitors of EPSP synthase
Resistance risk: Moderate

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Metsulfuron-methyl 300 g/kg + Aminopyralid 375 g/kg (Stinger™)
Rate: 20 g per 100 L of water
Comments: Spray after full frond expansion.
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

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Metsulfuron-methyl 600 g/kg (Various products)
Rate: 10 g per 100 L of water
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: B, Inhibitors of acetolactate synthase (ALS inhibitors)
Resistance risk: High

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Metsulfuron-methyl 600 g/kg (Various products)
Rate: 60 g/ha
Comments: Boom spray. Spray after full front expansion. Avoid spraying when plants are in stress.
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

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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.

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Reviewed 2021