Lippia

Native to South America, lippia is a summer-growing, broadleafed perennial herb. Lippia forms a solid, mat-like ground cover, with runners that take root at nodes. It can out-compete both native vegetation and pasture species.

Lippia is found in every Australian state and territory except for Tasmania. It is a serious environmental and pastoral weed in the Murray-Darling river system in Queensland and New South Wales. Lippia is well adapted to floodplains and adjacent areas, and is extremely difficult to control.

Lippia is not a prohibited or restricted invasive plant under the Biosecurity Act 2014.

Scientific name

Phyla canescens

Other names

  • Condamine couch, Condamine curse, phyla weed

Similar species

  • Phyla weed (Phyla nodiflora)

Description

  • Summer-growing, broadleaved perennial herb with thick, woody taproot.
  • Leaves are 1-3cm long, in pairs at stem nodes, have blunt serrated edge towards tip, taper to short stem.
  • Stems and leaves are greyish-green.
  • Flowers are small; tubular; white, cream, pinkish or pale lilac; 5-10mm in diameter.
  • Fruits are rounded, 1-1.5mm in diameter, split when mature to release 2 flat, brown, oval seeds.

Habitat

  • Well-adapted to floodplain environments and prefers heavy clay soils.
  • Readily establishes on bare ground and can take over large areas of land along waterways and adjacent higher ground.

Distribution

  • Well-established in Condamine and Border Rivers catchments in southern Queensland.
  • Present in Burnett region and Maranoa-Balonne and Warrego-Paroo catchments.

Life cycle

  • Flowers appear between spring and autumn.
  • Tolerates drought and frost, can survive long periods of inundation.

Impacts

Environmental

  • Serious environmental and pastoral weed in Murray-Darling river system.
  • Poses serious threat to protected wetland areas.
  • Dense carpet-like spread prevents growth of other riparian vegetation.
  • Resulting soil erosion decreases bank stability and degrades waterway health and quality.

Economic

  • Aggressive weed that out-competes pasture species, reducing stocking rates by up to 90%.

How it is spread

  • Spread by floodwater, seed dispersal, vehicles, machinery, birds and livestock.
  • Spread appears to be related to flood events, with significant rainfall and flooding likely to result in population 'explosions'.

Control

Mechanical control

  • Short-term control can be achieved where infestations can be ploughed or harrowed. This method is not practical if lippia is growing in riparian zones (such as creekbanks) due to high risk of erosion and soil loss.
  • Not usually a problem in cropping areas as can be readily ploughed into soil. However, machinery easily spreads lippia, so machinery working in infested areas should be washed down before leaving area.
  • When lippia is actively growing and soil moisture levels are good, herbicide can be used in conjunction with mechanical control to give better results.

Herbicide control

  • As lippia is a broadleaved weed that occurs in pasture situations, some herbicides can be used to reduce lippia without harming competitive grasses.
  • Limited herbicides registered for use, but no currently available herbicide will effectively suppress growth in the long term. Due to lippia's ability to rapidly recover and spread, multiple herbicide applications within a season have been shown to give better suppression than single applications. However, herbicide control can become costly in areas with large infestations.
  • Herbicide control is not suitable in riparian areas due to risk of polluting waterways. Also, herbicides should not be applied immediately after rain or if heavy rain is forecast.

See the lippia fact sheet (PDF, 714KB) for herbicide control and application rates.

Biological control

  • No known biological control agents.

Legal requirements

  • Lippia is not a prohibited or restricted invasive plant under the Biosecurity Act 2014. However, by law, everyone has a general biosecurity obligation (GBO) to take reasonable and practical steps to minimise the risks associated with invasive plants and animals under their control.
  • Local governments must have a biosecurity plan that covers invasive plants and animals in their area. This plan may include actions to be taken on certain species. Some of these actions may be required under local laws. Contact your local government for more information.

Further information