The April weed of the month is Groundsel bush (Baccharis halimifolia)
Groundsel bush is a menace of coastal floodplains, wetlands, forests, and agriculture. Its growing abundance means that it may soon become so widespread that it cannot be contained, and will continue to spread throughout the region.
Native to southern USA, Groundsel bush is thought to have been introduced to Brisbane as an ornamental shrub in the 1800’s. This hardy shrub is no longer considered desirable but continues to spread throughout southern Queensland and north-east NSW.
Groundsel enjoys high rainfall and tolerates most soil types, acid and alkaline conditions, waterlogged soil and high salinity. It grows best in full sun but can tolerate shade. It may be found in our coastal tea-tree wetlands, boggy or overgrazed pastures, banana plantations, roadsides, and forest plantations. Once a few plants are able to set seed it spreads quickly in suitable areas, taking over productive and marginal land, and threatening sensitive environments.
Why is Groundsel bush difficult to manage?
Groundsel bush has separate male and female plants, which are identical apart from the flowers. Their pollen and seeds are wind dispersed, with one female plant able to produce a million seeds per season! It may spread several kilometres in the wind but also spreads quickly in floods. The light, fluffy seeds are also notorious for sticking to machinery and are often spread vast distances on farm or construction machinery, easily finding a new area of disturbed ground to germinate in.
How to Spot Groundsel bush
A multi-stemmed shrub that can grow between 1.5 – 3m tall.
Leaves are waxy, around 5cm long by 3cm wide, and roughly diamond or oval-shaped with distinct blunt “teeth” around the tip.
Male flowers are 3mm wide and clustered at the ends of stems in creamy yellow heads, while female flowers are white and fluffy.
Glossy green, which can develop rough, brown bark on older stems.
When are you likely to spot Groundsel bush?
Groundsel bush is flowering throughout April-May, so now is the time to act on any infestations you see. Please contact Council’s Biosecurity officer for advice on identification and control of this highly invasive weed. Refer to NSW WeedWise for more information.
Image credits: Port Macquarie-Hastings Council & NSW WeedWise.
