Stemless thistle control

Page last updated: Monday, 15 February 2016 - 3:45pm

Please note: This content may be out of date and is currently under review.

Control methods for stemless thistle (Onopordum acaulon) a declared pest in Western Australia.

Report the presence of this pest before undertaking control

Information about this pest can be found on the stemless thistle: declared pest page.

Chemical requirements

When using any agricultural chemicals please ensure that you always follow instructions on the label and any permit. Users of agricultural chemical products must always strictly comply with the directions on the label and the conditions of any permit. To view permits or product labels go to the Australian Pesticides and Veterinary Medicines Authority website.

Control options

Chemical control options can be found below. For other methods of control please refer to the aquatic weed control page, and the declared plant control handbook.

Chemical control options

Recommended herbicides

Cropping; prior to sowing:

Chlorsulfuron; Triasulfuron

Seedlings:

2,4-D LV ester; 2,4-D amine; Dicamba

Young-mature plants:

Dicamba

Up to two leaf stage:

Tigrex®

Rosette up to 10cm maximum diameter:

Clopyralid

Pasture; up to two leaf stage: 

Tigrex®; Dicamba

Rosette up to 10cm maximum diameter:

Clopyralid + MCPA

At flowering:

Glyphosate + 2,4-D LV ester/2,4-D amine; Paraquat

Herbicide: Chlorsulfuron (Group B) (various trade names: see APVMA link)

Active ingredient

750g/kg chlorsulfuron

Rate of product/ha

15-20g

Time of application

Prior to sowing wheat and triticale

Remarks

Only registered in South Australia

More information and other control methods

These herbicides will damage clovers and medics

Herbicide: Triasulfuron (Group B) (various trade names: see APVMA link)

Active ingredient

714g/kg triasulfuron

Rate of product/ha

30-35g

Time of application

Prior to sowing wheat

Remarks

Only registered in South Australia

More information and other control methods

These herbicides will damage clovers and medics

Herbicide: 2,4-D LV ester (Group I) (various trade names: see APVMA link)

Active ingredient

  1. 600g/L 2,4-D LV ester
  2. 680g/L 2,4-D LV ester

Rates of dilution for spot spraying

  1. 1:250
  2. 1:280

Amount of product/10L water

  1. 30–35mL
  2. 25–30mL

Rate of product/ha

  1. 2.8–3.7L
  2. 2.5–3.3L

Wetting agent dilution

1:600

Time of application

Winter-spring: seedling to small rosette stage

Remarks

Pasture only. Thorough wetting is essential due to hairiness of leaf. Reaction to 2,4-D decreases as plants approach flowering. An APVMA permit is required to apply 2,4-D ester (80%) from 1 September until 1 May.

More information and other control methods

  • Grub individual plants at any time. Cultivation is effective up to rosette stage.
  • Paraquat/diquat for salvage. Chlorsulfuron, Metsulfuron methyl and MCPA + dicamba have proved effective in limited trial work.

Herbicide: Tigrex®

Active ingredient

250g/L MCPA (Group I) + 25g/L diflufenican (Group F)

Amount of product/10L water

10mL

Rate of product/ha

1L

Wetting agent dilution

1:400

Time of application

Up to two leaf stage

Remarks

Cereals and pasture. May cause transient yellowing to cereals and should not be applied to clover pasture before three trifoliate leave.

Herbicide: 2,4-D amine (Group I) (various trade names: see APVMA link)

Active ingredient

  1. 500g/L 2,4-D amine
  2. 625g/L 2.4-D amine

Rates of dilution for spot spraying

  1. 1:200
  2. 1:250

Amount of product/10L water

  1. 50mL
  2. 40mL

Rate of product/ha

  1. 5L
  2. 4L

Wetting agent dilution

1:600

Time of application

Winter-spring: seedling to small rosette stage

Remarks

Pasture only. Thorough wetting is essential due to hairiness of leaf. Reaction to 2,4-D decreases as plants approach flowering, rates should be increased above those recommended.

More information and other control methods

  • Grub individual plants at any time. Cultivation is effective up to rosette stage.
  • Paraquat/diquat for salvage. Chlorsulfuron, Metsulfuron methyl and MCPA + dicamba have proved effective in limited trial work.

Herbicide: Dicamba (Group I) (various trade names: see APVMA link)

Active ingredient

200g/L dicamba

Rates of dilution for spot spraying

1:750 - seedlings

1:375 - mature plants

Amount of product/10L water

15mL - seedlings

30mL - mature plants

Rate of product/ha

Grass pasture only

1.5L - seedlings

3.0L - mature plants

Time of application

Seedlings

More information and other control methods

A 500g/L formulation – use 1.2L/ha. Also a 750g/kg formulation (Cadence) is available. Apply at 200-400g for seedlings, and 400-800g for young to mature plants.

Herbicide: Clopyralid (Group I) (various trade names: see APVMA link)

Active ingredient

  1. 300g/L clopyralid
  2. 700g/kg clopyralid

Rate of product/ha

  1. 50mL + 1L MCPA amine or 700mL MCPA ester
  2. 20g + 1L MCPA amine or 700mL MCPA ester

Wetting agent dilution

1:400

Time of application

Rosette up to 10cm maximum diameter

Herbicide: Glyphosate (Group M) + 2,4-D ester (Group I) (various trade names: see APVMA link)

Active ingredient

360g/L glyphosate + 800g/L of 2,4-D ester.

Other concentrations of glyphosate and 2,4-D ester available.

Rate of product/ha

400mL of glyphosate + 500mL of 2,4-D ester.

Adjust rates for another concentrations of glyphosate and 2,4-D ester.

Time of application

At flowering

Remarks

Not recommended for south west Western Australia because of risk to commercial vines and vegetables. An APVMA permit is required to apply 2,4-D ester (80%) from 1 September until 1 May.

More information and other control methods

Other formulations of glyphosate available

Herbicide: Paraquat (Group L) (various trade names: see APVMA link)

Active ingredient

200g/L paraquat 

Rate of product/ha

2L/ha

Time of application

At flowering

Remarks

If plants actively growing they will recover and continue flowering

Contact information

Pest and Disease Information Service (PaDIS)
+61 (0)8 9368 3080