Herbicides for Cotton Thistle Control

Note: Cotton thistle (Onopordum acanthium) is often referred to as Scotch thistle on herbicide labels.

Disclaimer

These herbicide recommendations are made subject to the product being registered for that purpose under relevant legislation. It is the user's responsibility to check that registration or an off-label permit covers the proposed use. Always read the herbicide label.

If in doubt, check with the Australian Pesticides and Veterinary Medicines Authority (APVMA) website at www.apvma.gov.au.

Only herbicides registered for use in pasture and non-cropping situations - or included under off-label provisions - are listed in the following table. For recommendations in specific crops consult an agronomist.

Care must be taken in using herbicides as non-target plants contacted may be harmed.

Wetting agents

Most herbicides require a wetting agent for best results. Carefully consult the product label for specific directions regarding any adjuvants.

Waterways and wetlands

Be careful! Many herbicides can cause damage to waterways and wetlands. Check the herbicide label directions carefully before use near waterways and wetlands. For more information see Guidelines for Safe and Effective Herbicide Use Near Waterways.

Herbicide Brands and Concentrations

Herbicides are referred to by the active chemical ingredient in the following table. The product trade names in this publication are supplied on the understanding that no preference between equivalent products is intended and that the inclusion of a product does not imply endorsement by DPIPWE over any other equivalent product from another manufacturer. Information on available brands containing the herbicide you require should be obtained from a reputable herbicide supplier or the APVMA website at www.apvma.gov.au

There may be a number of products with the same active ingredient some with alternate formulations (concentration) registered for control of a weed eg: Glyphosate 360 g/L, Glyphosate 450 g/L may be registered for use on the same weed. Alternate formulations such as these will have a different application rate. Always check the label.

Boom spray application

Stage of Growth	Herbicide (active ingredient)	Example of commercial product (concentration of active ingredient)	Application rate of commercial product	Withholding period	Comments
Seedlings	Dicamba	Dicamba (500 g/L)	280 -560 ml/ ha	7 days	For control in pastures.
Young/ mature plants			560 - 1.1 L/ ha
Rosettes	Glyphosate	Glyphosate (450 g/L)	1.2 L/ ha	1 day	Non-selective and will damage or kill trees and grasses that come into contact with spray drift.
	MCPA + Dicamba	MCPA + Dicamba (340 g/L + 80 g/L)	2.8 - 4 L/ ha	7 days	Use higher rate on larger plants.
	Clopyralid	Lontrel (300 g/L)	50 or 70 mL + 1.0 - 1.5 L MCPA amine (500 g/L)	7 days	Apply during active growth. Use higher rate on larger plants. Clovers and medics will be eliminated for at least 12 months.

Spot spray application

Stage of Growth	Herbicide (active ingredient)	Example of commercial product (concentration of active ingredient)	Application rate of commercial product	Withholding period	Comments
Rosettes	MCPA + Dicamba	MCPA + Dicamba (340 g/L + 80 g/L)	1.9 - 2.7 ml/L	7 days	Use higher rate on larger plants.
	Clopyralid	Lontrel (300 g/L)	2.5 ml	7 days	Treat rosette stage prior to stem elongation. Clovers and medics will be eliminated for at least 12 months.
Seedlings	Dicamba	Dicamba (500 g/L)	40 ml /100 L	7 days	For control in pastures.
Young/ mature plants			76 ml/ 100 L
Seedlings - small rosettes	Diquat	Reglone (200 g/L)	300ml/ 100L	1 day	Add surfactant as recommended on label.