African Boxthorn

• African boxthorn is a woody shrub reaching up to 4 metres in height, with glossy leaves and an extensive root system incorporating a long branched taproot. The trunk and branches are light brown and smooth when young, turning darker brown or grey with age. The twigs end in a hard, sharp spike or thorn.

• The white flowers are usually produced in summer, although flowering can occur through most of the year. The fruit is an oblong berry approximately 10 mm long, going from a smooth green appearance to bright orange-red when ripe. Fruits contain numerous small, oval, flattened seeds. Seeds germinate at any time of the year and generally take two years to reach flowering stage.

• African boxthorn can be confused with the native tree violet (Hymenanthera dentate). Tree violet has yellow flowers and purple or white fruits, and the leaves tend to be narrower than the leaves of African boxthorn, and sometimes have toothed margins.

• For further help in identifying African boxthorn, search the Denni​s Morris Weeds and Endemic Flora database for African boxthorn illustrations. If you are still in doubt about the weed you are dealing with, contact Biosecurity Tasmania on 03 6165 3777 for help.

                   

African boxthorn in Tasmania

• African boxthorn is found throughout most agricultural areas of Tasmania, including King Island and Cape Barren Island. It is commonly found along fence-lines and beneath overhead wires, as well as along roadsides, railways and waterways.

• African boxthorn invades pastures and waste areas, reducing access and causing difficulty in stock movement. The spines can injure people, animals and vehicle tyres.

What is the legal status of African boxthorn in your area?

• The legal responsibilities of landholders and other stakeholders in dealing with African boxthorn are laid out in the African boxthorn Statutory Weed Management Plan.

• Use Table 1 (Zone A municipalities) and Table 2 (Zone B municipalities) in the Statutory Weed Management Plan to find out whether your area falls in an eradication or containment zone.

Do

• Hand-pull or dig up small bushes, and use machinery to remove larger bushes;
• Re-visit the site for follow-up removal of any regrowth;
• Cultivate the site and re-sow to pasture or crop to help prevent African boxthorn from re-establishing.

Don't

• Don't rely on one go at removal; follow-up treatment is essential to avoid re-infestation

Spread of African boxthorn

• Reproduction is mainly from seed. Birds eat the fruits and can spread the seed long distances from the parent plant. Seed can also be spread in mud or soil on machinery.
• African boxthorn can also grow from root fragments left in the soil.
• See the Washdown Guidelines for Weed and Disease Control for detailed information on how to wash-down equipment and personnel to reduce the chance of spreading African boxthorn.

Physical removal

• Large plants can be removed using heavy machinery. Uprooted plants should be destroyed as they can provide shelter for vermin and the spines can still cause injury.
• Small plants can be hand-pulled or dug up.
• After removal, the area should be monitored for regrowth from root fragments left in the soil, and for germinating seedlings.

Cultivation

• Areas cleared of African boxthorn should, if possible, be cultivated for pasture or crops.
• Cultivation of the soil breaks up any African boxthorn roots remaining in the soil and brings root fragments to the surface to dry out.
• Establishment of vigorous pasture or a crop provides competition with any regrowth of African boxthorn plants and reduces the chance of re-infestation.

Chemical control

• A number of herbicides are registered for use on African boxthorn in Tasmania. See Herbicides for African Boxthorn Control for more information.
• After herbicide treatment, African boxthorn often loses its leaves and appears to have died, but then produces new foliage.
• These regenerating bushes need to be re-treated with herbicide. This should be done when a significant amount of regrowth has occurred, allowing adequate uptake of the herbicide.