African Turnip Weed

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Quick Facts

Quick facts

  • African Turnip Weed (Sisymbrium thellungii) is a common weed in the Queensland cropping belt.
  • Herbicide resistant populations of African Turnip Weed have been recorded in Queensland.
  • African Turnip Weed is considered a weed of agriculture but it has also been recorded as a weed of natural systems.
  • African Turnip Weed is able to grow on a wide range of soil types and can invade cropping and pasture land.

What Does It Look Like?

What is it?

African Turnip Weed (Sisymbrium thellungii) is an annual herb that grows up to 60 cm tall. The stems and leaves are covered in backward-pointing stiff hairs. The basal leaves (up to 30 cm long) have 3-7 pairs of lobes, the terminal lobe being the largest. The upper leaves are similar in appearance to the basal leaves, but diminish in size along the stems. The flowers consist of four yellow petals. Each petal is up to 8 mm long. The fruits are long and narrow (7-12 cm long, 2-2.5 mm wide) and are usually covered in stiff hairs. The short stalks that attach the fruits to the stem point away from the stem, causing the fruits to be spread widely. The seeds are small (about 1 mm diameter) (Marais 1970; Hewson 1982).

For further information and assistance with identification of African Turnip Weed contact the herbarium in your state or territory.

Flower colour

Yellow

Growth form (weed type/habit)

Herb

Where it currently grows? Preferred habitat

In Queensland, African Turnip Weed has been found growing on a wide range of soil types as a weed of roadsides, railway lines, pasture, crops, fallow, alluvial flats, river banks and dry forest (Queensland Herbarium 2007).

Are there similar species?

African Turnip Weed can be distinguished from other species of Sisymbrium by the presence of long, roughly hairy fruits (up to 12 cm long) (Hewson 1982). However, in Australia, there are numerous weedy cruciferous species that are superficially similar in appearance to African Turnip Weed. Various weed guides, including Richardson (2007), Auld and Medd (1996) and Hussey et al. (2007) or the Herbarium in your state or territory should be consulted for further information on differentiating between these species.

Why Is It A Weed?

What are its impacts?

In Australia, African Turnip Weed is considered a weed of the natural environment and as a weed of agriculture (Randall 2007). In Queensland, it has been recorded invading pasture, wheat crops, fallow land, dry sclerophyll forest, disturbed areas, railway lines, roadsides, wetlands, riparian open forests and floodplains (Queensland Herbarium 2007). It is considered a common weed in the Queensland cropping belt (Dellow et al. 2006). African Turnip Weed can dominate crops and pastures. Young plants grow vigorously, even under moisture stress, out-competing other more valuable species (Wilson et al. 1995).

In South Africa, where it is considered native, it occurs as a weed in crops (especially cereals), waste areas, orchards and on roadsides (Bromilow 2001).

Seed of African Turnip Weed was found to be harmless to pigs even when fed at high levels (Blaney 2004).

How does it spread?

African Turnip Weed is an annual species, hence reproduction occurs by seed. Although no published information could be found on the dispersal mechanisms used by African Turnip Weed, it is assumed that it spreads in a similar manner to other annual weedy cruciferous species such as Wild Radish (Raphanus raphanistrum) and Sand Rocket (Diplotaxis tenuifolia). These species spread by water, especially where plants grow in riparian habitats and on steep terrain where erosion and runoff occurs. Contaminated soil, fodder, vehicles and other equipment are potential vectors for seed transport. Seeds may also be readily dispersed along roadsides during roadside maintenance works. Dispersal via contaminated agricultural produce is also a potential means of spread (Parsons & Cuthbertson 2001).

What is its history in Australia?

African Turnip Weed was first recorded in Australia in 1947 as a common weed on some fallow land in the Port Curtis district in Queensland (Queensland Herbarium 2007). It is not known how or why African Turnip Weed arrived in Australia.

How To Manage It?

Best practice management

Several populations of African Turnip Weed in Queensland have become resistant to Group B herbicides (Adkins et al.1997; O'Donnell 2004). Herbicide resistance in African Turnip Weed means that integrated weed management is needed to effectively manage the species in the long term. Chemical treatment is most effective after flowering and before seed set (Walker et al. 2006; Cheam & Barker 2007).

Please see the Australian Pesticides and Veterinary Medicines Authority for chemical information http://www.apvma.gov.au 

Does it have a biological control agent?

NO

When does it grow? (lifecycle/growth calendar)

Seedlings of African Turnip Weed emerge in late autumn and winter (Wilson et al. 1995). In Queensland, it has been recorded as flowering from mid winter through to early summer (Queensland Herbarium 2007).

Where Is It Found?

Which states and territories is it found?

NSW, QLD

What areas within states and territories is it found?

In Australia, African Turnip Weed is naturalised in south-east Queensland and north-east New South Wales (Hewson 1982). It is not common in New South Wales (Retter & Harden 1990) and has only been recorded from the New England Tableland region. In Queensland, it was first recorded in 1947 as a common weed on fallow land in the Port Curtis district. Herbarium records indicate that the species has been reported from the Queensland districts of Warrego, Cook, Darling Downs, North Kennedy, Mitchell, Moreton, Port Curtis, Leichardt, Burnett, Wide Bay and Maronoa (Queensland Herbarium 2007).

Where does it originate?

African Turnip Weed is native and widespread in the eastern part of South Africa (Marais 1970).

National And State Weed Listings

Is it a Weed of National Significance (WONS)?

NO

Where is it a declared weed?

NSW, WA

Government weed strategies and lists – Weeds Australia

Is it on the National Alert List for Environmental Weeds?

NO

Government weed strategies and lists – Weeds Australia

Is it on the Agricultural Sleeper List?

NO

Government weed strategies and lists – Weeds Australia

Names And Taxonomy

Main scientific name

Sisymbrium thellungii

Other scientific names (synonyms)?

Brassica brachypoda Thell.

Does it have other known common name(s)?

African Turnipweed

Bibliography

Australian Plant Census (2011) available at: Vascular Plants APNI (biodiversity.org.au).

Adkins, S. W., D. Wills, M. Boersma, S. R. Walker, G. Robinson, R. J. McLeod, and J. P. Einam. (1997). Weeds resistant to chlorsulfuron and atrazine from the north-east grain region of Australia. Weed Research. 37: 343-349.

Auld, B.A. & Medd, R.W. (1996). Weeds: an Illustrated Botanical Guide to Weeds of Australia. Inkata Press, Sydney.

Australia's Virtual Herbarium (AVH) (2007). Council of Heads of Australian Herbaria (CHAH). Available at: Home - AVH (chah.org.au)

Bromilow, C. (2001). Problem Plants of South Africa. Briza Publications, Pretoria.

Blaney, B. (2004). Weed Seeds Toxic to Pigs. Queensland Government, Department of Primary Industries and Fisheries.

Cheam, A. & Barker, J. (2007). Factsheet - Controlling seed set in Cruciferous weeds in pulses. CRC for Weed Management.

Dellow, J.J., Storrie, A., Cheam, A.H., King, W.McG., Jacobs, S. and Kemp, D.R. (2006). Major brassicaceous weeds in Australian agriculture. In Cheam, A.H. (Compiler) Wild Radish and other Cruciferous Weeds: Proceedings of a symposium held at The Department of Agriculture and Food Western Australia.

Harden, G.J. (2007). Sisymbrium thellungii O.E.Schulz in PlantNET - The Plant Information Network System of Botanic Gardens Trust, Sydney, Australia (Version 2.0). Available at: PlantNET - FloraOnline (nsw.gov.au)

Hewson, H.J. (1982). Brassicaceae in George, A.S. (Ed), Flora of Australia Volume 8-Lecythidales to Batales. Australian Government Printing Service, Canberra.

Marais, W. (1970). Cruciferae. In Codd, L.E., de Winter, B., Killick, D.J.B. & Rycroft, H.B. (eds): Flora of Southern Africa, Volume 13. Department of Agriculture Technical Services, Pretoria.

O'Donnell, C. (2004). Current status of herbicide resistance in the northern grain region - other. Cruciferous Weeds Symposium. Department of Agriculture and Food, Western Australia.

Parsons, W.T. & Cuthbertson, E.G. (2001). Noxious Weeds of Australia. CSIRO Publishing, Victoria.

Queensland Herbarium (2007). Data provided by the Queensland Herbarium on 29 November 2007.

Randall, R.P. (2007). The Introduced Flora of Australia and its Weed Status. CRC for Australian Weed Management.

Retter, L. & Harden, G.J. (1990). Brassicaceae, In Harden, G.J. (ed.): Flora of New South Wales, Volume 1. New South Wales University Press, Sydney.

Richardson, F.J., Richardson, R.G. & Shepherd, R.C.H. (2006). Weeds of the south-east: An identification guide for Australia. R.G. & F.J. Richardson. Meredith, Victoria.

Walker, S., Widderick, M. & Osten, V. (2006). Stopping herbicide resistance in Queensland. Queensland Government, Department of Primary Industries and Fisheries.

Wilson, B. J., Hawton, D. & Duff, A. A. (1995). Crop Weeds of Northern Australia. Queensland Department of Primary Industries, Brisbane.

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