Khaki weed

Khaki weed is a declared Class B and Class C weed.

Another name for this plant is Alternanthera pungens.

Khaki weed - habit 

Identification

You should use this as a guide. There may be other plants or weeds that look similar.

If you are unsure, contact the Weed Management Branch.

Habit

These features describe the habit of this plant:

  • prostrate, perennial plant
  • spreads over the ground
  • forms thick mats
  • dries out in the dry season after seeding.

Khaki weed - habit

Stems and branches

These features can identify the stems and branches:

  • stems form roots at the nodes.

Khaki weed - stems and branches

Leaves

These features can identify the leaves:

  • 1 - 3cm long
  • rounded with a slight taper at the end.

Khaki weed - leaves

Flowers

These features can identify the flowers:

  • occur as dense clusters in the axils of leaves
  • yellow to green when young
  • become straw coloured when mature
  • each flower is surrounded by stiff pointed bracts.

Khaki weed - flowers

Fruit and seeds

These features can identify the fruit and seeds:

  • forms a chaff coloured prickly burr about 1cm long
  • yellowish amber seeds 0.1 to 0.2cm diameter contained within the burr
  • produces large quantities of seed
  • easily distributed on rubber soled shoes, tyres, swags, clothing and animal hair.

Impact

Khaki weed can have all of the following impacts:

  • prickly seed bracts can cause injury to humans and animals
  • invades pastures, lawns, parklands, around bores and along river banks
  • invades disturbed areas, roadsides, degraded pastures and playing fields
  • competes with irrigated and dry-land lucerne and it contaminates hay.

Habitat and distribution

Khaki weed is a native of tropical America. It’s not known how it came to Australia, but it was first recorded in NSW in 1898, the in QLD in 1910. 

It is now widespread in parts of Australia including the NT where it has been recorded in the Darwin, Gulf, Katherine, Victoria River, Barkly and Alice Springs districts.

Spread prevention

Isolated plants should be hand removed and the area burnt to reduce the seed population. 

Care should be taken when mowing and walking through infested areas as this will spread the seeds.

You can prevent the spread of khaki weed by doing all of the following:

  • map infestations to help develop a management plan
  • control minor infestations, isolated outbreaks or seedlings first
  • designate wash down areas and actively work to prevent contamination of clean areas
  • monitor areas that you have treated and watch for re-infestations.

Control

Chemical control

The best time to treat khaki weed is from December to March. Below is a list of treatment methods that can be used.

Chemical and concentration Rate Situation, method and notes
2, 4-D amine 625 g/L
Various trade names
320ml / 100 L Seedling or adult (individuals or infestation):
Foliar spray - apply when actively growing
Glyphosate 360 g/L
Various trade names and formulations
10ml / 1 L Seedling or adult (individuals or infestation):
Foliar spray - apply when actively growing
MCPA 340 g/L + Dicamba 80 g/L
Various trade names
350ml / 100 L Seedling or adult (individuals or infestation):
Foliar spray

Non-chemical control

Hand pulling and grubbing

Weeds, including their roots, are physically pulled out of the ground by hand or using hand tools. This is an effective method of control for individual weeds and recent outbreaks that haven’t released seeds yet, but it requires a lot of labour.

Last updated: 27 June 2017