Fireweed control

Access all the information needed for control of this noxious weed, including weed identification, herbicide application and spray timings.


Fireweed description

Fireweed identification

Fireweed is a member of the Asteraceae plant family. It is a daisy-like plant with endearing yellow flowers. It comes in a herb form and originated from South Africa. Fireweed has a variable growth habit and leaf structure, growing from 10 to 50 cm high. In coastal districts the most common form of fireweed is a low, heavily branched, short-lived perennial plant. Although leaf shape and structure can vary, leaves are generally bright green, alternate, narrow with serrated, entire or lobed margins. The broader leaves are usually clasped around the stem and are 2–6 cm long, occasionally reaching 8–10 cm on vigorous and older plants.

Fireweed has a shallow, branched taproot with numerous fibrous roots, growing from 10 to 20 cm deep. Petal numbers are usually a constant 13. Plants flower mainly from April to September, with individual plants often having a wide range of flowering stages at any one time. Seeds are small (1–3 mm long), light and slender. They are cylindrical in shape, with a downy surface and attached to a pappus of fine, silky white feathery hairs. The plant produces large quantities of seed over long periods that are easily dispersed by the wind. Each flower produces between 100 and 150 seeds. Long distance dispersal also occurs by seeds on animals, in stock feed or in mud on vehicles. The main issue to farmers is that it can outgrow most useful pasture plants. Fireweed also readily invades pastures damaged by overgrazing and drought. Fireweed seems equally at home in low-elevation, arid pastures as in high-elevation, moist pastures.

Fireweed control

Controlling fireweed

Fireweed is a weed of national significance and is identified as being invasive, having the potential for widespread environmental, social and economical damage. Landowners and land managers at all levels are responsible for actively managing this weed.

For best results in control of fireweed, treat seedling plants prior to flowering. Both Grazon Extra and Trezac are registered for foliar/spot application.

Herbicides for control of fireweed

Product#Method of applicationRate*State
Grazon® Extra Herbicide Foliar spray 350 mL/100 L of water All
Trezac® Arylex® active Herbicide Foliar spray 200 mL + 210 mL Starane®
Advanced/100 L of water

# Note: Preferred product option in bold. * Consult label for details of growth stage and use, especially where range of rates is given.

Treatment timing

Timing – Nth NSW/Qld

When using foliar sprays always treat when plant is actively growing.

Grazon® Extra Herbicide
Trezac® Arylex® active Herbicide

Timing – Sth NSW

Grazon® Extra Herbicide
Trezac® Arylex® active Herbicide
Key: Best time to spray/treat Can spray/treat if conditions are suitable Do not spray/treat