How to get rid of Fireweed?

Fireweed in flower

Fireweed is a brightly coloured flowering plant that may look harmless to the untrained eye – but wow, can it pack a punch! Toxic to cattle and prone to rapidly spreading, fireweed is on the move throughout New South Wales and parts of Queensland. As a result, it’s crucial to learn how to identify and control fireweed and manage its impact before it wreaks havoc on your property.


What is fireweed?

Fireweed is a daisy-like herb that originated in southern Africa. It has been present in Australia for a little over a century – the first known record of fireweed was in the Hunter Valley in 1918 – and has proven tough to quash since. You’ll have seen, or at the very least, heard of fireweed if you live along Australia’s eastern coast, as it inhabits regions that span from central Queensland all the way to northern Victoria.

Fireweed bush


Why is fireweed a problem?

There are a few things that set fireweed apart from your run-of-the-mill weed, the most prominent being its ability to grow and spread like… well, wildfire. Invasive by nature, fireweed thrives in overgrazed and neglected pastures, and has no problem competing with existing plants.

The biggest issue when dealing with fireweed growth is the health of your livestock. If left untreated, fireweed can overwhelm pastures and kill off other plant species, leaving your cattle and sheep with nothing else to eat. Fireweed is highly toxic to stock, and can cause liver damage that often leads to slow growth, a whole host of other illnesses, and ultimately, death. Fireweed consumption renders your animals’ milk and meat tainted, too, making it more important than ever to get under control as to avoid severe production shortages and economic loss.


How to identify fireweed

Now that you know the potential effects of fireweed on your livestock and your business, it’s time to learn how to identify it. Fireweed resembles many other flowering weeds, such as daisies, but don’t be fooled by its sunny yellow flowers – this plant is far from friendly. You’ll be able to differentiate fireweed from less harmful plants by looking carefully at its flowers and leaves. In a dry climate, fireweed can peak at less than 20cm tall, and will be characterised by narrow leaves, little to no branches, and very few flowers. In ideal conditions, however, fireweed will appear much healthier, at up to 50cm in height and with over 100 flowers in many cases.

Fireweed bush on pasture

Its leaves can be anywhere from 2cm to 6cm long, and are dark green in colour with serrated edges and a noticeably light green centre ‘vein’. A fireweed flower is bright yellow with roughly 8-14 petals, and is approximately 2cm in diameter. The seeds are cylindrical in shape and come in at about 2-3cm long, with rows of fine hairs. The plant has a shallow taproot with many fibrous roots.


How does fireweed grow and spread?

Fireweed is an annual plant, meaning that it completes its life cycle from growth to death in just one season. Fireweed seeds germinate in mild, warm conditions with lots of light and moisture – in Australia, you’ll see their seedlings pop up between March and June. They tend to produce their first flowers very quickly, often in just 6-10 weeks, making them tricky to get a handle on. A dry summer followed by a wet autumn and winter creates the perfect conditions for a fireweed infestation, which at its very lightest can produce a whopping million seeds per hectare.

It’s no wonder that fireweed is known for its insidious nature – this opportunistic plant loves varying conditions, and grows at a breakneck speed. These traits combined with its uncanny ability to spread beyond belief make fireweed a tough plant to get under control, but it is imperative that you do so to avoid irreversible damage to your land. The best time to eradicate fireweed is before its flowers form and the seeds have a chance to spread.

If you’re dealing with fireweed that has already flowered, the seed can be spread in a number of ways, including by the wind, through your livestock, by wild animals, and through human activity. It can also spread if it unintentionally comes into contact with materials like pasture seed, hay, turf, and mulch. Fireweed seeds typically fall within 5 metres of the parent plant, but it’s common for windy conditions to spread the seed much further.


How to effectively control fireweed

It’s very apparent that if you are trying to protect the health of both your land and your livestock, fireweed can put a massive spanner in the works. So, to avoid the damage that can easily unfold if it spreads, it’s important to take measures to control fireweed growth.

Once the weed has been identified, immediate action is essential. A dense pasture in autumn and winter will help to prevent fireweed from cropping up, and increase the chances of successful eradication.

If you are already dealing with an infestation of fireweed, the best course of action is to use a herbicide. Herbicides are most effective if sprayed before plants reach maturity, so if possible, begin this process prior to the fireweed’s flowering. However, if this isn’t an option for you, not all is lost – application during flowering can be effective if higher-than-usual rates of herbicide are applied. While research into herbicide control for fireweed is still ongoing, studies currently show that application in autumn, around April, provides the best control.

Before beginning a herbicide program, we advise determining the infestation levels on your land to influence how you administer your herbicide. An effective application method in an open pasture is a boom spray, which can then be followed up by spot spraying, or pulling and bagging any regrowth or missed plants. Boom spraying is also suitable for follow-up treatments, as it allows the destruction of immature plants, which can grow and reseed the area before they are even noticed.


The best herbicides for fireweed

There are a number of herbicides suitable to treat fireweed. The correct one for your needs will depend on the stage of the plant, with different products designed to be effective at the seedling stage, all the way to flowering.

  • Bromicide 200 Selective Herbicide is one of the most effective herbicides when fireweed is at the seedling stage. It can be applied during autumn and winter when fireweed plants are young and actively growing. Bromicide 200 also offers flexible application by either ground or air. This product contains the active ingredient bromoxynil, and so, is suitable for use in pastures containing clovers, medics, and lucerne, and will not affect grasses. Twice as much product is recommended if your fireweed is just beginning to flower. As a contact-only herbicide, Bromicide 200 is less effective on mature plants.
  • Surefire Decimate Selective Herbicide includes two key active ingredients – bromoxynil and diflufenican – and is used for cereals, and in vineyards and some improved pastures. Surefire Decimate is registered to control fireweed up to the four-leaf growth stage. It is best known for its exceptional broadleaf weed spectrum and fast action, producing visible effects within days, rather than weeks. This herbicide removes competitive weed species and other broadleaf weeds in broadacre crops and dynamic clover or lucerne pastures.
  • Grazon Extra is a premium-control option for foliar application on hard-to-kill noxious and woody weeds. It is effective against mature fireweed plants including at the flowering stage. It contains three active ingredients – picloram, triclopyr, and aminopyralid. These combined offer the broadest weed control of any product currently on the market. Grazon Extra provides outstanding knockdown and residual weed control against a range of weeds, including fireweed, without harming pasture grasses.


Fireweed can be challenging to completely eradicate once established, but with the right tools and knowledge, this is perfectly possible. Be sure to select the right herbicide for your needs, and don’t skimp on follow-up treatments.


Have any questions?

Want to know more about this tricky weed? The Specialist Sales team is always available to answer any questions you may have about effectively treating fireweed, and to offer our advice on finding the right products for your needs. Get in touch with us today and we’ll be glad to offer you our expertise.

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