Lagarosiphon control

Page last updated: Saturday, 28 September 2019 - 11:43am

Please note: This content may be out of date and is currently under review.

Control methods for Lagarosiphon (Lagarosiphon species) a declared pest in Western Australia.


Information about this pest can be found on the Lagarosiphon: 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

Chemical control options

Chemical control options can be found below. For other methods of control please refer to the aquatic weed control page.

Recommended herbicides

  • Diquat​
  • Dichlobenil

Diquat (Group L) (various trade names: see APVMA link)

Active ingredient

200g/L as diquat dibromide monohydrate

Rate of product/ha


Time of application

Actively growing plants

Wetting agent

As recommended on label Agral @ 200mL/100L water or BS-1000 @ 160mL/100L


Treatment will not work in muddy water

Further information

  • Retreatment will be necessary
  • Bio-control and mechanical harvesting not effective on large areas

Casoron (Group K)

Active ingredient

65g/kg dichlobenil

Rate of product/ha

  • 1.7–2.3kg/100m2 for water less than 1m
  • 2.3–3.4kg for water greater than 1m depth

Time of application

Apply at end of dormant period, usually July-August


Apply to still water

Further information

  • Toxic to fish and other aquatic life so care with use needed
  • Terbutryn used in the United Kingdom but is not registered in Australia for aquatic use

Contact information

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