Cotton Bush (Gomphocarpus fruticosus)

Narrow Leaf Cotton Bush is a tall and slender shrub originating from Southern Africa. The white flowers form in drooping clusters from October to April. The distinctive seed pods are puffy, swan-shaped structures covered in soft spines. It has become widespread in southern WA. Narrow-leaf cotton bush spreads by seed, which usually germinate in spring or autumn, but can germinate at any time of year if warm, moist conditions prevail. Plants can re-sprout from the crown or root if parts of the plant above ground are damaged. The entire plant is poisonous to humans and stock, and the sap is a skin irritant. Small infestations can be treated via hand pulling, ensuring all the root material is removed. Chemical control via foliar spraying or cut and paint techniques can be extremely effective, especially on large infestations.

Some guidance for controlling cotton bush includes: 

  1. Prevention: The best way to control cotton bush weed is to prevent it from establishing in the first place. This can be done by monitoring and controlling new infestations early, as well as avoiding activities that may spread the plant’s seeds (such as mowing or slashing). Long-term control of cotton bush can be challenging and time-consuming, and may require ongoing efforts over several years. Please contact LBG for guidance on developing an effective long-term control plan for your specific situation.
  2. Manual removal: Pulling up cotton bush weed by hand can be effective for small infestations, especially when the soil is moist. Be sure to wear gloves to protect your hands from the plant’s toxic sap.
  3. Cut and paint: Cut the stem of the cotton bush weed as close to the ground as possible and immediately paint the cut surface with a herbicide that contains glyphosate or triclopyr. This method is particularly effective for larger plants.
  4. Grazing: Cattle and goats can be used to graze on cotton bush weed. This can be effective for controlling large infestations, but it requires careful management to prevent overgrazing and damage to other vegetation.
  5. Herbicide spraying: Herbicides such as glyphosate can be effective for controlling cotton bush weed. However, herbicides can be harmful to other plants and animals, so it’s important to carefully follow the instructions on the label.

Guidance for Managing Cotton Bush in During Autumn and Winter Months
Even though Cotton Bush can grow year round, we are coming to end of the optimum herbicide treatment control period.  However note, manual removal of cotton bush plants remains an effective control method year round.  If you have cotton bush on your property, we recommend you the note current location of any plants currently growing as it will likely re-germinate in the spot next year.

To control “fruiting cotton bush plants” (pods growing) please follow these steps:

  1. manually remove pods to prevent further seed spread
  2. secure pods in closed plastic bin bag and leave in sun to kill seeds (black bags preferred to promote accelerated solarisation)
  3. conduct manual removal or spray of actual plants (see DPIRD Control Guidance)

Recommended 100-metre cotton bush-free “buffer zone” between properties
While sometimes it may not be practical to remove all cotton bush plants from your property, it is important to create a sufficient cotton bush-free buffer zone of recommended 100 metres from your property boundaries.  This 100 metre “buffer zone” recommendation is based on research that has demonstrated that cotton bush seed travels on average 25m from the parent plant in the first year of the reproduction cycle. Consequently, a factor of four times that distance (100m) was devised to act as a suitable buffer zone from wind dispersal between neighbouring properties. If neighbouring properties adhere to this guidance, we can greatly minimise the continued spread of this pest.  This buffer helps reduce the spread through anemochory (wind dispersal), which is the primary biological method of seed dispersal of cotton bush. As such, these plants naturally strive to grow tall to enhance the wind’s ability to spread its seeds.  Once you have removed any tall plants from your property, it is much easier to effectively manage control of any seedlings and smaller plants.

Contact LBG to discuss Cotton Bush Control guidance or concerns:  
e-mail: info@lbginc.org.au   phone: 0477 049 967

PLEASE help us map distribution of this invasive weed in our area.  

LBG, along with several other community groups is working with the South West Catchment Council and CISRO to help develop new tools for controlling narrow leaf cotton bush (Gomphocarpus fruticosus) in Western Australia.  As part of this work, we need to map the full distribution of this weed, ideally down to every population.  The distribution of this invasive weed in WA as it is currently recorded on the Atlas of Living Australia is far from the actual distribution across the state.  If you see cotton bush, please report it!  Your reporting can help fill in gaps on the current cotton bush map and will be greatly appreciated!

To report cotton bush sightings, here’s what to do:

  1. Please download DPIRD’s MyPestGuide™ Reporter app to your smartphone.
  2. Report any cotton bush plants you find, along with any insects or disease that you notice on the plants.
  3. Send in a sample (details provided in the app) if you notice anything else interesting.

A full step by step set of instructions can be found for download here:  [Cotton bush sampling instructions]