Family: Asteraceae (daisies)

Status: Noxious in category W2 in Eurobodalla and Bega Valley Local Government Areas (must be continually suppressed and destroyed), and in category W2 or W3 (must be prevented from spreading and controlled to Council’s satisfaction) in Shoalhaven LGA depending on location.

Description:
A low bushy or sprawling annual herb to about 30cm high, with bright green alternate slightly fleshy hairless leaves. Leaf margins are usually entire (smooth) but may have some teeth or lobes especially near the base. Yellow daisy flowers have thirteen petals. Small "dandelion" style seed heads break up in the wind, though not as readily as many other weedy daisies. Roots are shallow and branching, and generally easy to pull out by hand.

Preferred habitat and impacts:
Roadsides, pasture, and adjacent open forest, preferring areas of bare soil to become established. It needs moist conditions for seedling establishment, but will grow and flower at any time of year other than mid-winter, given the rainfall. From germination to flowering can take as little as 6 weeks. Plants behave as annuals in southern areas, because they are frost tender, but may over-winter and behave as short-lived perennials further north.

The plant is toxic to stock, causing progressive liver damage. It is not readily grazed except by sheep and goats, which tolerate the toxins better than other stock. Plants can become extremely numerous in heavily grazed paddocks because stock avoid them.

Potentially a serious weed of remnant grassy native vegetation in farming areas, although it seems to invade healthy vigorous native pasture less readily than grazed and fertilised pasture.

Dispersal:
Seed is wind-blown, and possibly moved around in soil and on vehicles, since it often becomes established on roadsides.

Look-alikes:
There are many other weedy yellow daisies. Most of these consist of a single basal rosette and flower stalks arising from the centre, rather than having a bushy, branched habit. Their flowers tend to be a deeper yellow than those of fireweed.

There are also numerous native herbs in the genus Senecio. Among these, fireweed can be distinguished by its 13 petals, and fibrous root system. Two very similar natives are Senecio lautus ssp maritimus, which occurs on sea cliffs and dunes and has fleshier leaves and a taproot, and S. lautus ssp lanceolatus which occurs in wet grassy forest along the top of the coastal escarpment. The latter has a more spreading, lax habit than the weed and slightly larger flowers. Senecio madagascariensis may also occur behind beaches or on top of the escarpment, so check the appearance of the plant as well as the location before making an identification.

The large clumping native perennial, Senecio linearifolius, can behave in a weedy way around the edges of the farming areas, where it colonises after fire or other disturbance. If in doubt, get a specimen professionally identified.

Control:
Fireweed is easy to hand-pull, unless soil is quite dry, in which case it may break off. Remove as soon as the plants become visible by beginning to flower. Bag the whole plant for safe disposal, or bag flowers and seed heads and turn the rest of the plant upside-down to dry it out. Do not leave the flowers or seed heads in the paddock. Search also for seedlings which are not yet flowering in the vicinity of the more visible plants. Spot spraying or boom spraying can be used for larger infestations.

Sheep can help reduce seed-set by grazing the plant. Maintaining a vigorously growing pasture is helpful in preventing infestation. Occasional burning of native pasture may make it more resistant to infestation, by stimulating active grass growth.