Spear thistle (Cirsium vulgare)

Also known as: black thistle

Profile

Impact

Spear thistle is mainly a weed of agricultural areas and wasteland. It competes with sown species, inhibits livestock movement and causes both fault in wool and physical injury to animals. 

Description

Spear thistle has dark green leaves that are white and ‘woolly’ underneath. It has purple flower heads.

References

Auld B.A. and Medd R.W. (1999). Weeds. An illustrated botanical guide to the weeds of Australia. (Inkata Press, Melbourne). 

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Control

Biological control

Three biological control agents have been released for spear thistle in NSW. A seed fly (Urophora stylata) is established with reasonable impact on seed production of spear thistle. Two weevils, a seed head weevil (Rhinocyllus conicus) and a crown weevil (Trochosirocalus horridus) were released, but their establishment is unknown. 

Herbicide options

WARNING - ALWAYS READ THE LABEL
Users of agricultural or veterinary chemical products must always read the label and any permit, before using the product, and strictly comply with the directions on the label and the conditions of any permit. Users are not absolved from compliance with the directions on the label or the conditions of the permit by reason of any statement made or not made in this information. To view permits or product labels go to the Australian Pesticides and Veterinary Medicines Authority website www.apvma.gov.au

See Using herbicides for more information.


2,4-D amine 625 g/L (Amicide® 625)
Rate: 1.1–1.6 L/ha
Comments: Boom spray. For pastures not containing legumes. Spray young rosettes.
Withholding period: 7 days.
Herbicide group: I, Disruptors of plant cell growth (synthetic auxins)
Resistance risk: Moderate


2,4-D LV ester 680g/L (Estercide® Xtra)
Rate: 1.15 to 2.1 L per hectare
Comments: Boom spray application, from seedling to rosette stage
Withholding period: 7 days
Herbicide group: I, Disruptors of plant cell growth (synthetic auxins)
Resistance risk: Moderate


Fluroxypyr 140 g/L + Aminopyralid 10 g/L (Hot Shot™ )
Rate: 500 ml in 100 L of water
Comments: Hand gun application to actively growing plants
Withholding period: 7 days. See label for export restrictions.
Herbicide group: I, Disruptors of plant cell growth (synthetic auxins)
Resistance risk: Moderate


MCPA 500 g/L (Various products)
Rate: 1.5–2.0 L/ha
Comments: Boom spray. Apply to rosettes actively growing; use higher rate on larger plants.
Withholding period: 7 days.
Herbicide group: I, Disruptors of plant cell growth (synthetic auxins)
Resistance risk: Moderate


Picloram 100 g/L + Triclopyr 300 g/L + Aminopyralid 8 g/L (Grazon Extra®)
Rate: 150 mL in 100 L of water
Comments: Foliar application from rosette to flowering plants
Withholding period: Where product is used to control woody weeds in pastures there is a restriction of 12 weeks for use of treated pastures for making hay and silage; using hay or other plant material for compost, mulch or mushroom substrate; or using animal waste from animals grazing on treated pastures for compost, mulching, or spreading on pasture/crops.
Herbicide group: I, Disruptors of plant cell growth (synthetic auxins)
Resistance risk: Moderate


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Biosecurity duty

The content provided here is for information purposes only and is taken from the Biosecurity Act 2015 and its subordinate legislation, and the Regional Strategic Weed Management Plans (published by each Local Land Services region in NSW). It describes the state and regional priorities for weeds in New South Wales, Australia.

Area Duty
All of NSW General Biosecurity Duty
All plants are regulated with a general biosecurity duty to prevent, eliminate or minimise any biosecurity risk they may pose. Any person who deals with any plant, who knows (or ought to know) of any biosecurity risk, has a duty to ensure the risk is prevented, eliminated or minimised, so far as is reasonably practicable.

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Reviewed 2014