Fireweed (Senecio madagascariensis)

Fireweed looks like a daisy with little yellow flowers. It invades pastures and can poison livestock.

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How does this weed affect you?

Fireweed can:

  • take over pastures
  • make grazing animals sick or die.

Fireweed is hard to get rid of. Each plant produces up to 30,000 seeds in a season.

Livestock poisoning

Fireweed contains chemicals called pyrrolizidine alkaloids. Livestock that eat it get liver damage. The damage is irreversible and gets worse the more fireweed an animal eats. Hay, silage or grain contaminated with fireweed plants or seeds can poison livestock.

Identifying fireweed poisoning is tricky. Other things like mineral deficiencies or internal parasites can cause similar symptoms. If you think you have affected animals contact your vet.

Cattle

Cattle are usually reluctant to eat fireweed. Young, hungry or new stock not familiar with fireweed are more likely to eat it. Cattle can lose weight, or their growth slows. Some develop brain damage, which can show as confusion and poor coordination. Sudden death can happen in fat cattle that have eaten fireweed in the last 3 to 6 months.

Sheep and goats

Sheep and goats are more inclined to eat fireweed than cattle. They are also up to 20 times more tolerant of its toxins. Merinos tend to eat less fireweed, other sheep breeds can eat it to excess. Sheep that eat fireweed over two or more years may become unwell or die suddenly. Sheep and goats rarely show signs of brain damage.

Fireweed can poison alpacas too, but less is known about the effects on them.

Horses

Horses have more problems with fireweed poisoning. Unpigmented skin can become sensitive to sunlight, redden and peel away. Brain damage is common. Symptoms can include:

  • dullness
  • aimless wandering
  • an uncoordinated gait
  • pressing up against fences, gates or trees
  • reduced awareness, and possible blindness.

What does it look like?

Fireweed plants are 10–60 cm tall. Most fireweed is low growing, with many branches. You can see most stages of the plant (seedlings to flowering) at almost all times of the year. Flushes of seedlings appear after rain in warm weather.

Leaves are:

  • bright green
  • fleshy and narrow
  • 2–7 cm long and 3–10 mm wide
  • staggered (not opposite each other) on the stems
  • serrated, smooth or lobed on the edges.
  • clasped around the stem when large.

Flowers are:

  • small, yellow and daisy-like
  • 1–2 cm across
  • in clusters at the ends of branches
  • commonly with 13 petals per flower
  • emerging from a small cup of modified leaves called bracts.
  • usually with 21 bracts forming the cup structure.
  • more abundant on some plants than others (0-200 per plant).

Seeds are:

  • small and light
  • 1–3 mm long
  • cylindrical in shape
  • downy on the surface
  • attached to fine, white feathery hairs that aid in dispersal by wind.

Roots are:

  • fibrous
  • 10–20 cm deep
  • branched from a central taproot.

Similar looking plants

Variable groundsel (Senecio pinnatifolius) is sometimes confused with fireweed. It’s a native Australian plant, not considered a weed. Often it grows in places where fireweed is unlikely to be, such as bushland and undisturbed sites.

Where is it found?

Fireweed grows along the Australian east coast from Victoria to Central Queensland. It is most invasive in coastal regions. It’s also on the northern and southern tablelands of New South Wales (NSW). Inland NSW has isolated areas of fireweed.

Fireweed comes from southeast Africa. It was first seen in the Hunter Valley in 1918.

What type of environment does it grow in?

Fireweed thrives in:

  • overgrazed pastures
  • disturbed or cultivated soil
  • most soil types.

Fireweed is less active in:

  • shaded areas
  • wet areas – it does not survive waterlogging.

Distribution map

How does it spread?

Wind spreads the light, fluffy seeds. Most seeds fall within five metres of the parent plant. Some seed travels further on windy days. The fluff can come away from the seed. The detached fluff can move long distances on the wind.

Spreading beyond one kilometre is more likely through human activity. Fireweed reaches new areas via:

  • livestock
  • clothing, vehicles and machinery
  • contaminated hay, silage and grain products
  • movement of seed by wild animals.

Do not bale pastures with fireweed for silage or hay.

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Control

Long-term fireweed control needs to consider that:

  • most new seedlings appear in autumn
  • many new seedlings appear after rain when temperatures are 15–27°C
  • seedlings grow fast and can flower 6–10 weeks after emerging
  • flowering and seeding occur mostly in spring
  • most plants die off by late spring
  • some plants live for up to three years - the tops die back in spring and regrow the following autumn
  • fireweed seed buried deeper than two centimetres is unlikely to germinate
  • long-term follow up is essential because about 15% of seeds remain dormant for over 10 years.

In pastures, combine:

  • grazing strategies
  • pasture improvement
  • strategic herbicide use.

In environmental areas:

  • hand-pull individual plants
  • spot spray herbicide.

Avoid introducing it

Avoid bringing hay, feed or silage from known fireweed areas onto your property.  Keep checking feedout areas and paddocks for fireweed plants. Control them before they flower and seed.

Look out for it

Spot fireweed plants in new areas and act quickly to control them.

Maintain healthy pastures

Maintain healthy pastures as the best long-term defence against fireweed. Have good autumn–winter pasture cover to suppress new fireweed plants. Avoid grazing too hard. Weeds like fireweed then establish in thin and bare patches. To maintain healthy pasture cover:

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


Improve poor pastures

Large patches of bare ground and lots of weeds are signs of poor pastures. Pasture improvement to control fireweed is proven to work best north of Sydney where there’s more rain in summer). South of Sydney it rains more in winter and pastures are slower to establish. Selective herbicides may be needed to control fireweed until pastures mature. Pasture improvement aims to:

  • sow vigorous pasture plants that compete with fireweed
  • cover bare soil
  • correct soil fertility problems

and adjust grazing to:

  • always keep at least 90% of the ground covered with good pasture plants
  • have even higher cover during peak fireweed germination in autumn
  • reduce numbers of grazing animals before overgrazing.

Be careful with fertilisers. Applying them before competitive pasture species are present can increase the fireweed problem.

Suitable summer-growing pasture species include:

  • setaria
  • kikuyu
  • paspalum
  • Rhodes grass.

Winter or spring-growing pasture species include:

  • phalaris
  • cocksfoot
  • fescue
  • ryegrass
  • white clover
  • subterranean clover.

Consult your agronomist for appropriate pasture species, fertiliser recommendations and pasture establishment techniques. More fireweed can germinate after disturbing the soil.

Tillage

An agronomist can advise on a crop program to support fireweed control in arable areas. This can reduce the fireweed seed bank before sowing a perennial pasture. Tillage in March and April stimulates many fireweed seeds to germinate. Control the seedlings with a  knockdown herbicide or more tillage. Avoid over-cultivation, which increases the risk of erosion. Then sow a forage crop that will give dense cover to suppress remaining fireweed.

Native pastures

Seek advice from your Local Land Services office when improving native pastures. Some activities are restricted.

Grazing to control fireweed

Grazing fireweed harms all animals. Even though sheep and goats can tolerate it the effects build up over time. Don’t force stock to eat only fireweed. Make sure other feed is available. Avoid grazing fireweed in late spring as it can promote its survival into the following year.

Sheep and goats

The best animals to control fireweed by grazing are:

  • goats or sheep wethers intended for slaughter
  • other sheep if you can use a new group of animals each year.

Merinos seem to be more resilient than other sheep breeds. Avoid pushing breeding stock of any species including sheep and goats to graze fireweed.

Cattle and horses

Cattle and horses normally avoid eating fireweed and heavily graze other pasture plants. This favours the growth of fireweed. Always match grazing pressure of cattle and horses to the available pasture growth or the fireweed will increase.

Hand weeding

Pull out individual plants in small, isolated patches or sensitive environmental areas. Wear gloves to protect skin from the plant’s poisons. Bag and dispose of the pulled out plants. They are still poisonous to livestock and produce viable seeds if they have flowers.

Slashing and mulching

Careful slashing or mulching can reduce fireweed seeding when done:

  • before late spring
  • when less than 25% of plants are flowering
  • at least every six weeks if pastures can recover faster than the cut fireweed plants

Wait two weeks before grazing slashed areas. Livestock are more likely to eat the cut, wilted fireweed.

Avoid slashing or mulching in late spring, or when more than 25% of plants are flowering. This can trigger plants to regrow, surviving into summer rather than dying off at the end of spring. That makes next season’s control harder.

Biological control

There are no effective biological control agents available for fireweed. It’s difficult to find a biological control that’s harmless to the native Senecio species.

These insects can attack and sometimes destroy fireweed plants:

  • A chrysomelid beetle (Chalcolampra species)
  • A magpie moth (Nyctemera amica)
  • A blue stem borer moth (Patagoniodes farinaria).

They cannot be relied on for control. The damage usually occurs after the plants have produced seeds.

Chemical control

Herbicides are most effective in combination with healthy, competitive pastures. The best time to treat fireweed with herbicide is late autumn. This controls the peak numbers of seedlings and young plants. By late winter herbicide treatments are much less effective.

Used correctly, selective herbicides don’t kill grasses but do slow their growth. They can kill legumes, which are important pasture plants. Blanket applications of selective herbicide are problematic because pasture growth is set back. Wherever possible limit the application areas in paddocks.

Bromoxynil herbicides cause the least damage to legumes but only kill young fireweed plants. Protect legumes by applying only when the maximum daily air temperature will be below 20°C. Metsulfuron-methyl herbicides can kill older fireweed plants, but also kill pasture legumes.

Flowering plants can be spot sprayed with herbicides containing aminopyralid or metsulfuron-methyl.

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.


Bromoxynil 200 g/L (Bromicide®)
Rate: 1.4 L/ha
Comments: Boom spray. Seedling application. In pastures apply with low volume boom spray during autumn/winter when weeds are young and actively growing. Observe withholding period.
Withholding period: 8 weeks.
Herbicide group: C, Inhibitors of photosynthesis at photosystem II (PS II inhibitors)
Resistance risk: Moderate


Bromoxynil 200 g/L (Bromicide®)
Rate: 2.8 L/ha
Comments: Boom spray. Early flowering application. In pastures apply with low volume boom spray during autumn/winter when weeds are young and actively growing. Observe withholding period.
Withholding period: 8 weeks.
Herbicide group: C, Inhibitors of photosynthesis at photosystem II (PS II inhibitors)
Resistance risk: Moderate


Bromoxynil 250 g/L + Diflufenican 25 g/L (Jaguar)
Rate: 500 mL per ha
Comments: Booms spray application, up to 4 leaf stage
Withholding period: 14 days
Herbicide group: C, Inhibitors of photosynthesis at photosystem II (PS II inhibitors) + F, Bleachers: inhibitors of carotenoid biosynthesis at the phytoene desaturase step (PDS inhibitors)
Resistance risk: Moderate/Moderate


Fluroxypyr 140 g/L + Aminopyralid 10 g/L (Hot Shotâ„¢ )
Rate: 500 mL in 100 L of water
Comments: Apply to flowering plants up to 30 cm tall
Withholding period: 7 days. See label for export restrictions.
Herbicide group: I, Disruptors of plant cell growth (synthetic auxins)
Resistance risk: Moderate


Fluroxypyr 140 g/L + Aminopyralid 10 g/L (Hot Shotâ„¢ )
Rate: 1.5 L/ha
Comments: Treat seedling plants up to flowering
Withholding period: 7 days. See label for export restrictions.
Herbicide group: I, Disruptors of plant cell growth (synthetic auxins)
Resistance risk: Moderate


Picloram 100 g/L + Triclopyr 300 g/L + Aminopyralid 8 g/L (Grazon Extra®)
Rate: 350 mL in 100 L of water
Comments: Apply as a thorough foliar spray
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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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.
All of NSW Prohibition on dealings
Must not be imported into the State or sold
Central Tablelands
Exclusion zone: Whole region except for the core infestation area of Bylong Valley and Kanimbla Valley (lower Cox River Catchment)
Regional Recommended Measure*
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 mitigate spread from their land.
Central West Regional Recommended Measure*
Land managers should mitigate the risk of the plant being introduced to their land. The plant should be eradicated from the land and the land kept free of the plant.
Murray Regional Recommended Measure*
Land managers should mitigate the risk of new weeds being introduced to their land. The plant should be eradicated from the land and the land kept free of the plant. Notify local control authority if found.
Riverina Regional Recommended Measure*
Land managers should mitigate the risk of new weeds being introduced to their land. The plant should be eradicated from the land and the land kept free of the plant. Notify local control authority if found.
South East
Exclusion zone: whole region except the core infestation area of Wollongong, Kiama, Shellharbour, Eurobodalla, Shoalhaven, Bega Valley and Wingecaribee councils
Regional Recommended Measure*
Whole region: Land managers should mitigate the risk of new weeds being introduced to their land. Exclusion zone: The plant should be eradicated from the land and the land kept free of the plant.
*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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For technical advice and assistance with identification please contact your local council weeds officer.
For further information call the NSW DPI Biosecurity Helpline on 1800 680 244 or send an email to weeds@dpi.nsw.gov.au

Disclaimers

Pasture improvement may be associated with an increase in the incidence of certain livestock health disorders. Livestock and production losses from some disorders are possible. Management may need to be modified to minimise risk. Consult your veterinarian or adviser when planning pasture improvement. The Native Vegetation Act 2003 restricts some pasture improvement practices where existing pasture contains native species. Inquire through the NSW Office of Environment and Heritage for further details.

Reviewed 2018