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Artichoke Thistle | LC0191 |
Department of Primary Industries
Updated: August 2007
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Common and Scientific Names
Artichoke thistle
Cynara cardunculus L.
Origin and Distribution
Artichoke thistle is a native of the Mediterranean regions and was first reported in Victoria at Williamstown in 1884. Infestations are present throughout central Victoria, extending from the Murray river at Echuca to Melbourne and westerly.
Description
Artichoke thistle is a stout, erect, greyish perennial which forms a rosette of very large leaves and usually grows to a height of 60 to 150 cm, although occasional plants are found over 2 metres high. Seeds germinate mainly in autumn and the plant usually flowers in its second summer. It grows mainly on medium to heavy soils in pastures, on roadsides and creeklands, waste lands and vacant industrial areas.
Stems - of mature plants are branched, strongly-ribbed and covered with cottony down. There is usually only one stem per plant, but may be as many as eight. The stems are produced in spring and bear flower heads at the end of each branch in summer.
Leaves - vary considerably in length; the basal leaves can be up to 1 m long and 30 cm wide, whereas the stem leaves are often only 15 cm long. The upper surface of the leaves is a greyish-green colour, while the under surface appears almost white because of a dense mat of white hairs. The leaves are much divided, each lobe ending in a sharp, yellow spine.
Flowers - blue to purple in colour, 5 to 13 cm in diameter, and surrounded by a series of stout bracts each ending with a spiny tip. Flowering occurs from December to February.
Seeds - 6 to 8mm long, brown or black in colour, and topped by a loosely attached pappus (parachute) of feathery bristles, up to 40 mm long.
Roots - large fleshy taproot, somewhat like an oversized parsnip, which may grow to a depth of 2 metres. New growth develops from the crown each year.
The Problem
Artichoke thistle has the ability to dominate the vegetation of an area once it becomes established. The large plants smother most pasture growth as well as drawing much moisture and nutrient from the soil. It may also compete with crops and impede harvesting operations. The prickly nature of the leaves deters sheep and cattle from areas of heavy infestation.
Heads from the heavy infestations around Melbourne have been collected and treated in the same way as globe artichokes (Cynara scolymus) for eating. Globe artichoke has fleshier flowers with fewer spines and has not become a weed. Hybrids of the two species have been identified in Victoria. Artichoke thistle has also been used as a cut flower for decoration.
Artichoke thistle is thought to cause contact dermatitis with some people.
Dispersal
The pappus aids the dispersal of the seed by wind, but it is not very effective because of the weight of the seed. Most seeds drop within a few metres of the parent plant as they separate from the loosely attached pappus, whilst others may blow as far as about 20 metres.
Seed is also spread by animals and birds, and by flood waters. The careless disposal of cut flowers also contributes to dispersal. Fragments of cut root will generate new plants in favorable conditions. | Figure 1. Artichoke thistle flower.
Figure 2. Artichoke thistle. |
Management Program
Some control methods described in this note are only effective if used in combination with other control options as part of a long-term management program.
If used in isolation, these methods do not effectively destroy the plant, allowing it to re-shoot or continue to grow. Authorised officers from DPI or DSE may direct landowners to undertake specific control activities to ensure methods are used that are capable of destroying plants and preventing their spread.
Where directed to do so, landowners must use the method or methods as directed by the authorised officer. In most cases the landowner will be able to choose from a variety of options appropriate for use in their particular situation.
There are different control techniques appropriate for addressing different levels of infestation of artichoke thistle. These control techniques need to be integrated into a strategy to gain best long term control. Clean areas of land should be kept free of artichoke thistle and managed to prevent infestation. Lightly infested areas should be treated as soon as possible to prevent spread. Extensive infestations should be quarantined and tackled progressively as part of an eradication program or pasture improvement.
Manual Control
Physical grubbing out of isolated plants is reasonable with very small infestations. It is necessary to remove much of the taproot to prevent new growth. The application of an appropriate herbicide to the exposed root significantly increases the effectiveness of this method.
Cultivation
Can be effective if repeated each time new growth appears. However repeated cultivation may lead to soil erosion and breakdown of soil structure.
Pasture management
The establishment and maintenance of a good perennial pasture will help control artichoke thistle but is not impervious to infestation. Land managers must be diligent and treat individual plants as soon as they are detected.
Chemical Control
Spraying of artichoke thistle should be undertaken during spring before flowering stalks are produced.
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 Chemical Standards Branch 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 artichoke 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’ which 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 Chemical Standards Branch website.
Use a product containing active constituents or combinations of active constituents registered for use in Victoria to control artichoke thistle in the particular situation in which you need to use chemical control, eg. in pastures. Consult the product label for detailed information.
Further Advice
- Contact your local landcare or friends group for further assistance and advice.
- Call the DPI/DSE Customer Service Centre on 136 186.
- Contact your local DPI Pest Management Officer for advice on local programs.
- Visit the DPI website
- Weeds Australia (external link)
Reference
Parsons, W.T. and Cuthbertson, E.G. (1992) Noxious Weeds of Australia. Melbourne, Inkata Press.
Acknowledgements
Prepared by R Williamson; Information & Assessment, Keith Turnbull Research Institute (KTRI), 1996. Updated by I. Faithfull, KTRI, January 1998. Updated by Melanie Martin, DPI, October 2006. Chemical information supplied by Chemical Standards Branch August 2006. Updated by Deven McPhan, 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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