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Annual ragweed
- Annual ragweed plant
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- Annual ragweed infestation
General information
Annual ragweed (Ambrosia artemisiifolia), also called ambrosia, horseweed and asthma plant, was introduced into Australia from North America.
Annual ragweed is a Class 2 declared pest plant under Queensland legislation.
| Scientific name |
Ambrosia artemisiifolia |
| Impacts |
- invades weed and overgrazed pastures, reducing productivity
- infestations can become particularly dense in pastures which are overgrazed
- pollen contains highly potent allergens that can cause respiratory allergies such as hayfever and aggravate asthma
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| Description |
- 1-2 m high with slightly rough fern-like, deeply divided with hairy undersides
- small, greenish flowers up to 20 cm long in the upper part of the plant
- flower spikes appear yellow when mature because of pollen production
- male flowers at the top of the spike and females at the base
- seeds black, small, top-shaped and rough
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| Habitat/distribution/life cycle |
- naturalised in South East Queensland and northern New South Wales with infestations occurring near Stanthorpe, Inglewood, Gympie, Gin Gin and Atherton
- often colonises bare areas on roadsides and banks of watercourses and can invade pastures from these areas
- seeds can spread by floodwater, be introduced with stock, or arrive as a contaminant in fodder or topsoil from infested areas
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| Control |
- a combined approach of different control methods including chemical, mechanical, fire and biological with land management practices is most effective
- see the annual ragweed fact sheet for further information
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| Declaration details |
- a declared Class 2 species under the Land Protection (Pest and Stock Route Management) Act 2002
- landholders are required to control declared pests on their properties
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| Further information |
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Page maintained by Sonia Jordan
Last reviewed 08 September 2011
