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Amsinckia | LC0198 |
Department of Primary Industries
Updated: August 2007
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Common and Scientific Names
- Amsinckia, Yellow Burrweed
- Amsinckia calycina (Moris) Chater
- Amsinckia lycopsoides Lehm.
- Amsinckia intermedia Fischer & C.Meyer
- Amsinckia menziesii (Lehm.) A.Nelson & Macbride
Origin and Distribution
Amsinckia originated in North and South America and was introduced to Australia late in the nineteenth century. It belongs to the same plant family, Boraginaceae, as Paterson’s curse and common heliotrope. Four species of amsinckia are now naturalised in Victoria.
Amsinckia is a significant weed in many northern cereal-growing areas in Victoria with annual rainfall over 275 mm. It is also an important weed in mixed farming areas.
Description
Free-standing, erect, winter growing annual herbs, usually 20 to 70 cm high, covered with long and short hairs. Seeds germinate with the first autumn rains and further germinations occur through autumn and winter. Seedlings have rough leaves and pronounced forking of the cotyledons. The plant grows as a rosette during winter and a flowering stem emerges in late winter or spring. Plants die after seed is set in late spring or summer.
Stems - Erect, unbranched or branched, covered with stiff hairs or bristles.
Leaves - To 20 cm long, lance-shaped, alternate, covered with short stiff hairs or bristles, stalkless and stem-clasping on the upper part of the plant, shortly stalked on the rosette.
Flowers - From late August to November, yellow to orange with 5 petals fused into a trumpet shape, up to 6 mm long, produced along a crook-shaped head (the cyme) which increases in length as the inflorescence matures (Figure 2). Flowers are self pollinating.
Fruit and Seeds - The fruit consists of a bristly husk or burr (the calyx) surrounding four nutlets, each containing a single seed. Seed are 2 to 3.5 mm long, brown to black in colour, ridged, roughly triangular and coarsely granular. A plant may produce up to 1600 seeds. | |
Roots - Tap root with numerous laterals; not extensive.
The Problem
Amsinckia has the potential to establish over a wide range of soil types and climates. Germination of the seeds in autumn gives the plant an advantage over many other species. Only a small amount of the seed germinates at one time.
Amsinckia competes strongly with cereal crops and heavy infestations can cause large yield losses. Early competition reduces tiller number in wheat. To safegaurd cereal crop yields, amsinckia needs to be eliminated during the first few weeks of growth.
Seed can contaminate grain. The bristly calyx contaminates wool. Bristles on the leaves and stems make the plant unattractive to stock and it is generally unpalatable.
Alkaloid substances toxic to the liver and causing skin photosensitisation are present in the foliage of one species of amsinckia with cattle, horses and pigs being susceptible. Stock deaths due to consumption of amsinckia have not been confirmed in Australia.
Dispersal
Seed is effectively spread on farm equipment and in contaminated fodder. Sowing of contaminated seed grain and other contaminated seeds also spreads the weed. Dispersal may occur when the bristly calyx lodges in the coats of feral animals and stock, and when seed is carried in the digestive tracts of birds and stock. | Figure 2. Amsinckia flowers are
produced along a crook-shaped
head which increases in length
as the inflorescence matures. |
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.
Mechanical Control
In cereal fallows repeated cultivations destroy seedlings from early germinations but follow up herbicide treatment is needed after crops are sown. Repeated harrowing can be effective on seedlings. Hand pulling can be suitable for small areas. On grazing lands mowing or slashing just before flowering can effectively reduce seed production and if undertaken repeatedly will deplete the soil seedbank.
Pasture Management
Competition from pasture legumes suppresses amsinckia during the fallow phase on lands used for cereal growing.
Grazing of goats has been used to control amsinckia. | Figure 3. Amsinckia rosette. |
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 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 amsinckia 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 CSB website.
Use a product containing active constituents or combinations of active constituents registered for use in Victoria to control amsinckia in the particular situation in which you need to use chemical control, eg. in pastures. Consult the product label for detailed information.
In cereal crops the economic threshold for herbicidal control is 25 amsinckia plants per square metre. Several herbicides are available, and are most effective at the seedling stage.
Biological Control
The potential for classical biological control of amsinckia has been investigated in the USA. No biological control agents are available for use in Australia.
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
Code, G. (1998) Weed Control in Pastures 1998. Rutherglen, Agriculture Victoria, Department of Natural Resources and Environment.
Code, G. (1998) Weed Control in Winter Field Crops 1998. Rutherglen, Agriculture Victoria, Department of Natural Resources and Environment.
Parsons, W.T. and Cuthbertson, E.G. (1992). Noxious Weeds of Australia. Inkata Press, Melbourne.
Acknowledgements
Prepared by Ian Faithfull, Keith Turnbull Research Institute. Updated by Melanie Martin, DPI, October 2006. Chemical information supplied by Chemical Standards Branch, August 2006. Updated by John James, 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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