Landcare Agony Aunt – Fireweed Fields of Gold

Dear Agony Aunt,

Everywhere I look across the paddocks of my farm, there are clumps of yellow flowers.  They’re creating a far-reaching, golden horizon that is rapidly multiplying and competing with my native pastures. My stock generally avoid the plants if there are other things in the paddock, but they do sometimes feed on them and get sick when there’s not much else to eat. I’ve driven along the entire east coast of Australia and I’ve seen this plant everywhere. Is there anything I can do?

from Fed up on the Farm, Fosterton

Dear reader,

Oh dear!  It looks like you’ve got Fields of Gold … Fireweed!

The F word on everybody’s lips. Fireweed. This weed is what constitutes the majority of the Hunter’s unwanted ‘Fields of Gold’.

Fireweed or Senecio madagascariensis, hails from South Africa, and yes, also Madagascar. (There are a couple of other species which have also become environmental weeds in Australia, those being Senecio angulatus and Senecio glastifolius).

Senecio is part of the Asteraceae family (the Daisy family), and is termed a ‘cosmopolitan genus’, meaning it’s a bit of a gadabout and has graced most continents with its presence. It was first seen in the Hunter Valley in 1918 in Raymond Terrace. It grows along the Australian east coast from Victoria to Central QLD.

It is worth noting that this weed is listed as one of the notorious 32 Weeds of National Significance (WONS), and also as one of the Priority Weeds for the Hunter.

Most people can recognise this frustrating fiend by its bright green, fleshy, narrow leaves with smooth, toothed or lobed edges that occur alternately along the stems, and the small, yellow daisy-like flowers with up to 15 petals in clusters at the ends of branches. Then there are the small and light cylindrical seeds – downy on the surface, that are attached to fine, white, feathery hairs that allow them to blow easily in the wind.

This fiery foe thrives in overgrazed pastures, cultivated or disturbed soils and, disappointingly, most soil types. It does not like shaded or wet areas, particularly waterlogged ones.

One of Fireweed’s (many) unsavoury features include:

•   Reducing productivity on farms.
•   Being difficult to control – An average fireweed plant can produce over 10 000 seeds per year.
•   It 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. Fireweed is toxic whether it is green or dry, so contaminated hay or feed can be toxic.

 So, how to curb the enthusiasm of this golden-haired child?

There are several measures you can take to reduce the impact of this festering fugitive.

For pastures, best practice is combined grazing strategies, pasture improvement and strategic herbicide use. In natural environments, hand-pull individual plants before seed-heads appear and spot spray herbicide for larger infestations.

Long term fireweed considerations:

• Most new seedlings appear in autumn.
• Flowering and seeding occur mostly in spring.
• Long-term follow up is essential because about 15% of seeds remain dormant for over 10 years.
• Most plants die off by late spring.

Avoid introducing it: Senecio can occur in hay, silage or feed, so check the sources and avoid bringing these onto your property from known fireweed hotspots. Remember, Fireweed is still toxic if it is dry.

Maintain healthy pastures:  Weeds like fireweed establish in thin and bare patches. So, having good autumn–winter pasture cover to suppress new fireweed plants is a good idea, as is avoiding grazing too hard. 

Improve poor pastures: Lots of bare ground and lots of weeds are an indication of poor pastures. Sow vigorous pasture plants to outcompete Fireweed.  Adjust your grazing system to allow higher ground cover during peak Fireweed germination in autumn.

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 your stock to eat only fireweed. Make sure other feed is available. Avoid grazing fireweed in late spring which can promote its survival into the following year. For more information on the tolerance levels of horses, cattle, sheep and goats, click here.

Hand weeding:  With gloves, hand pull smaller patches of fireweed. Bag and dispose responsibly.

Slashing and mulching:  This needs to be 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. 

Biological control: There are no biological controls for Fireweed, because these will put native Senecio at risk. Chrysomelid beetle (Chalcolampra species), Magpie moth (Nyctemera amica) and Blue stem borer moth (Patagoniodes farinaria)  can attack and sometimes destroy Fireweed, however, the damage usually happens after the plants have produced seeds, so can’t be relied upon as an effective management solution.

Chemical control: This option can be most effective when used in conjunction with competitive pastures. For best results with herbicide control, treat fireweed in late autumn. For more comprehensive information on herbicide control, click here.

Did you know that this weed has its very own National Best Practice Management Manual:

Fireweed (Senecio madagascariensis) National Best Practice Management Manual 2023

It’s not all bad:

Take heart Landcarer.  Not all Senecios are created equal. There are approximately 50 native species, one being Senecio magnificus, occurring in semi-arid areas on NSW, Victoria, NT and SA, and a couple of others in NSW including Senecio garlandii  or Woolly Ragwort; and Senecio linearifolius var. dangarensis which is restricted to two known populations occurring on basalt cap peaks of the Goulburn River and Wollemi National Parks.

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.

All the best with fighting this far-reaching, fiery foe.  You have many frustrated friends joining you in the battle!