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Tropical soda apple (Solanum viarum)

A prickly shrub that has spread through pasture and riparian areas of south-east Queensland and northern New South Wales, often moved by cattle and floods.

Key facts

Type: Weed, shrub.

Native to: South America.

Established in: QLD, NSW.

Identification

  • Shrub to 2 m with broad, lobed leaves and straight, cream to yellow prickles on stems and leaves.
  • White flowers with yellow centres.
  • Round fruit up to 3 cm that is mottled green like a small watermelon, ripening yellow.

Where it grows

Pasture, creek banks, forest edges and cattle camps.

Why it matters

  • Reduces pasture and forms thickets.
  • Fruit is not readily eaten by stock; hosts crop pests and diseases.

How it spreads

  • Cattle, feral pigs and birds eat the fruit and spread seed.
  • Floodwater, contaminated hay and machinery.

Control options

  • Treat with registered herbicides before fruit forms.
  • Hold cattle from infested areas before moving them, as seed passes in dung.

Hygiene and washdown

  • Clean vehicles and machinery, and quarantine stock from infested paddocks.
  • Inspect and clean vehicles, plant and footwear before leaving an infested area, paying attention to tyres, radiators, belly plates, tracks and floor mats.
  • Wash down at a designated bay where runoff is contained and can be monitored for seedlings.
  • Record each washdown so the client has evidence of clean entry and exit.

Classification by state

  • Australia (national): No national listing. Managed under state and territory law.
  • Queensland: Restricted matter, categories 2, 3, 4, 5. Report it to Biosecurity Queensland within 24 hours; do not give it away, sell or release it into the environment; do not move it; do not keep it. Everyone must also take all reasonable and practical steps to minimise its risks (the general biosecurity obligation).
  • New South Wales: Control order. A state control order applies, so follow its eradication and reporting requirements. The general biosecurity duty applies: anyone dealing with it must prevent, eliminate or minimise the risk it poses.
  • Victoria: Not declared. Not declared under the Catchment and Land Protection Act 1994. Other Victorian laws may still apply.
  • South Australia: Not declared. Not declared under the Landscape South Australia Act 2019. Other laws may still apply.
  • Western Australia: Declared pest (C1), prohibited. C1 Exclusion: to be kept out of WA, or out of the parts of WA where it is not established. Report any sighting to DPIRD. It must not be brought into WA (prohibited organism).
  • Tasmania: Not declared. Not a declared weed in Tasmania. Other laws may still apply.
  • Northern Territory: Check NT list. There is no NT weed profile for it. Check the NT declared weeds list for its current status.
  • Australian Capital Territory: Not declared. Not declared under the Biosecurity Act 2023 (ACT). A general biosecurity duty still applies.

Legal obligations

Every state and territory places a duty on landholders and people working on land to prevent the spread of invasive species, such as the general biosecurity obligation in Queensland and the general biosecurity duty in New South Wales. Declarations and control requirements differ between states and local government areas, so check the current official list before work starts.

  • Queensland: Biosecurity Act 2014 (Qld), administered by Biosecurity Queensland (13 25 23)
  • New South Wales: Biosecurity Act 2015 (NSW), administered by NSW Department of Primary Industries and Regional Development

Sources