Fireweed has been established in the eastern escarpment of the Northern Tablelands for many years. But more recently, Biosecurity Officers have been noticing fireweed establishing further west, along roadsides and in paddocks on the Tablelands. It is a serious pasture weed on the east coast of Australia, from Victoria to Central QLD, and isolated areas in inland NSW.
It originally comes from south eastern Africa, and can take over pastures. Fireweed produces pyrrolizidine alkaloids and livestock that eat it get liver damage, which causes loss in condition and can lead to death. The damage is irreversible and gets worse the more fireweed consumed. Cattle and horses are more prone to this than sheep and goats.
Identification
Fireweed plants are 10cm to 60cm tall. The flowers are small, bright yellow, daisy-like with usually 13 petals. Leaves are bright green, fleshy, narrow and can be serrated, smooth or lobed on the edges. They are alternatively arranged on the stem, stalkless and tend to clasp the stem. Seeds are light, fluffy and easily carried long distances by the wind, and shorter distances by livestock. Fireweed is hard to get rid of, as each plant can produce up to 30,000 seeds a season. Fireweed seedlings appear in autumn after rain when temperatures are 15°C – 27°C. Seedlings grow fast and can flower 6–10 weeks after emerging. Flowering and seeding occurs mostly in spring. The plants generally die off by late spring, though some plants live for up to three years - the tops die back in spring, and regrow the following autumn. Long-term followup is essential, because about 15% of seeds remain dormant for over 10 years.
Fireweed is a highly invasive and opportunistic weed which can quickly colonize disturbed areas, including roadside and overgrazed pastures. To reduce introducing new fireweed to your property, do not purchase hay, silage or grain produced in contaminated areas and always check feedout areas and paddocks for fireweed plants.
Fireweed can be controlled through hand pulling (as plants are shallow rooted), chemical application, grazing strategically (sheep and goats can graze for short periods where other feed is available in pasture) and pasture management. 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. A pasture with at least 90% ground cover is far less susceptible to invasion by fireweed.
Images: Fireweed in flower (above). At left: Fireweed flower close up.
For help with weed identification and management, please contact any of the Biosecurity Officers (Weeds) at the New England Weeds Authority on 02 6770 3602, call into their offices at 2/129 Rusden St, Armidale and 144 Otho St, Inverell; follow the Facebook site or visit www.newa.com.au.
