Nodding Thistle

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Nodding Thistle: State Prohibited Weed	LC0282
Department of Primary Industries Updated: August 2007 To view the Adobe Acrobat file, you will need the Adobe Acrobat Reader (external link).	(PDF 130kb)

Common Name

Nodding thistle, Musk thistle

Botanical Name

Carduus nutans L.
Family Asteraceae

Status

Nodding thistle is one of 25 weeds proclaimed as State Prohibited Weeds in Victoria. This is the highest category to which a noxious weed can be allocated and means that nodding thistle is to be eradicated if possible from the State. The Victorian Government has responsibility for the control (and eradication) of State Prohibited Weeds, irrespective of where they might occur.

Origin

Nodding thistle has its origins in Europe, North Africa, Asia Minor and Asia. It came to Australia as a contaminant of seed from New Zealand before 1950.

Description

Nodding thistle is an erect annual, or usually biennial, and occasionally triennial herb, most often 80 to 120 cm high. It usually has a single stem which branches in the upper half, but may become multi stemmed if the crown is damaged. Plants exist as a rosette before the stem elongates.

Stems - erect, grooved, slightly downy with spiny wings from the base of leaves to below the flower heads; up to 150 cm tall.

Leaves - rosette leaves up to 50 cm long, spiny and pressed to the ground and becoming deeply lobed into the whitish midvein. Each lobe ends in a spine about 3 mm long and lobes often have a whitish margin. Stem leaves up to 40 cm long, deeply lobed to the midvein, hairy, with rigid spines.

Flowers - pink, red, purple, mauve or rarely white; formed in solitary woolly heads, up to 6 cm diameter, at the ends of branches; flower heads at first upright but distinctively drooping at right angles to the stem when mature. Each flower head is surrounded by many purplish bracts which terminate in a sharp rigid spine. Individual flowers are 4 to 8 mm across.

Seeds - 3 to 4.5 mm long with lines from end to end and faint dots; slightly curved, shiny, finely wrinkled and grey to yellowish brown. There is a rim at one end with a conical tip to which fine white bristles 15 to 25 mm long are attached. This pappus is easily separated from the seed.

Figure 1: Nodding thistle.

Roots - substantial branched taproot down to 40 cm or more deep.

Life Cycle

Seed germination is usually from late summer to early winter and flowering occurs from spring through summer to autumn. Some germination may occur in spring and early summer. These plants remain in the rosette stage until their second spring when they shoot up a main stem and flower, thus acting as biennials.

Dispersal

Seed is the only means of reproduction. It may be carried as a contaminant of produce seed and hay, on vehicles and machinery, and in water and soil. Because the pappus easily separates from the seed, wind does not have a major role in dispersal and seed are usually not blown more than 10 m.

General

Nodding thistle is not readily grazed and the large size of the plants can quickly prevent stock access to pastures. Because the main germination period is late summer and early autumn nodding thistle can invade fertile annual pastures as the favoured pasture species die off. Nodding thistle infestations have been recorded in the eastern part of Victoria.

Management

The Department of Primary Industries is responsible for the control of State Prohibited Weeds. Any person who believes they have located an infestation of nodding thistle, regardless of the area, please notify a Pest Management Officer at a local office of the Department of Primary Industries or advise the Customer Service Centre (telephone 136 186). Chemical control will usually be used, especially for larger infestations. Small infestations or isolated plants may also be treated by physical control (cultivation or hand-grubbing). Best-practice management will need to take account of the large tap root of each plant, seed heads and soil seedbank at each site. Ongoing monitoring of treated sites, and the destruction of any seedlings before flowering is essential for eradication of individual infestations to be achieved.

Chemical Control

The Australian Pesticides & Veterinary Medicine Authority (APVMA) is responsible for the assessment and registration of agricultural and veterinary chemicals in Australia. As chemical products are registered on a daily basis and renewal of these registrations are undertaken each financial year, there is much change in the registration status of products each year. The information is available from APVMA (external link).

The Chemical Standards Branch (CSB) of the Department of Primary Industries provides information on agricultural chemicals registered in Victoria and their uses. Enquiries will be referred through the Customer Service Centre on 136 186. Information can also be obtained by visiting the CSB website.

Under Victorian legislation there are controls on the use of agricultural chemicals. It is the responsibility of the user to be familiar with these controls. These responsibilities are outlined in Information Note AG0520: “Responsible use and handling of farm chemicals”.

Farm chemicals are registered for specific uses. Each chemical has a ‘product label’, which documents the approved use and the approved rate of use within each State of Australia. This label is important in determining the appropriateness of chemical use.

Choose only products registered for use on nodding thistle in your particular situation. Read the product label carefully and follow all label instructions.

Your chemical retailers can provide information on registered chemical products that are available in their store. They can also supply a ‘material safety data sheet’ that outlines the health and safety issues associated with use of a product.

Legal use of some restricted chemicals requires the user to possess an Agricultural Chemical User Permit (ACUP). Other chemicals have restrictions on their use in Agricultural Chemical Control Areas (ACCAs).

Information on ACUPs, ACCAs and other chemical information can be found at the CSB website.

References

Parsons, W.T. and Cuthbertson, E.G. (1992) Noxious Weeds of Australia. Melbourne, Inkata Press.

Popay, A.I. and Medd, R.W. (1995) Carduus nutans L. ssp. nutans. Pp. 29-49 in Groves, R.H., Shepherd, R.C.H. and Richardson, R.G. (Eds.) The Biology of Australian Weeds Volume 1. Melbourne, R.G. and F.J. Richardson.

Acknowledgements

Prepared by R Williamson; KTRI 1996. Updated by I. Faithfull, KTRI, January 1998. Updated by Chris Shorten, DPI, June 2007. Chemical information supplied by Chemical Standards Branch August 2006. Updated by Michael Hansford, DPI, August 2007.

The advice provided in this publication is intended as a source of information only. Always read the label before using any of the products mentioned. The State of Victoria and its employees do not guarantee that the publication is without flaw of any kind or is wholly appropriate for your particular purposes and therefore disclaims all liability for any error, loss or other consequence which may arise from you relying on any information in this publication.

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