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Sticky nightshade (Solanum sisymbriifolium)

Sticky nightshade competes with crops and pastures, prevents native plants from growing and can make harvesting difficult. Its sharp prickles can injure people and animals, and it contains toxins suspected of causing cattle deaths in the Greater Sydney Region.

Key facts

Type: Weed, herb.

Native to: South America.

Established in: QLD, NSW, ACT, VIC, WA.

Other names: viscid nightshade, litchi tomato.

Best time to act: Check regularly, as plants can flower within five weeks of germination or regrowth from rhizomes; flowering is usually in spring and summer, and spraying is advised on actively growing plants.

Identification

  • An erect annual or short-lived perennial, it grows up to 1.5 m high and is hairy with very sharp prickles.
  • Its sticky, green to yellowish leaves are deeply lobed and prickly on both sides.
  • White or pale bluish-purple, star-shaped flowers have five backward-curving petals and bright yellow anthers.
  • Round berries turn bright red when ripe; before ripening, they are enclosed in a green prickly husk.
  • Yellow to red prickles occur on stems, both sides of leaves, leaf stalks and at the base of flowers.

Where it grows

In NSW it is mostly found in Western Sydney and the Central Tablelands, with isolated infestations in other regions except the Western region, growing in full sun or semi-shade in varied environments and soil types, best in moist conditions.

Why it matters

  • It competes with crops and pastures and prevents native plants from growing.
  • Its sharp prickles can injure people, pets, livestock and native animals.
  • It can make harvesting difficult, for example in vineyards.
  • It contains steroidal glycoalkaloid toxins and is suspected to have caused cattle deaths in the Greater Sydney Region.

How it spreads

  • Birds and foxes spread viable seeds after eating ripe fruit; fruit can also be blown along the ground or carried by water and runoff.
  • Seeds can spread on slashers, in contaminated soil and fodder, and on cultivation and earthmoving equipment.
  • Root and rhizome fragments can grow into plants, and branches can develop roots where they touch moist soil; plant fragments spread in contaminated soil and on machinery.

Control options

  • Chip or dig out small plants, remove all roots, and wear protective clothing, boots and gloves to avoid prickles.
  • Avoid cultivating infested areas and slashing, as these can spread the weed; if cultivation is unavoidable, remove plant fragments and soil from machinery before it leaves the site.
  • Use registered herbicides according to their labels and permits, thoroughly covering leaves and stems on actively growing plants; spraying does not kill viable seeds.
  • Remove fruit from treated plants and dispose of it appropriately; contact your local council for disposal advice.

Hygiene and washdown

  • Remove contaminated soil and plant fragments from cultivation and earthmoving machinery before moving it from an infested site.
  • Avoid moving contaminated soil or fodder, which can spread seeds.
  • 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: Not prohibited or restricted. Not listed as prohibited or restricted matter in Queensland. Everyone must also take all reasonable and practical steps to minimise its risks (the general biosecurity obligation).
  • New South Wales: Regional priority in 4 of 11 regions. Regional priority weed in Hunter, North Coast, Northern Tablelands, South East. 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: Permitted, not declared. Listed as a permitted organism in WA, so it can be brought in, but it is not a declared pest.
  • 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
  • Australian Capital Territory: Biosecurity Act 2023 (ACT), administered by ACT Biosecurity
  • Victoria: Catchment and Land Protection Act 1994 (Vic), administered by Agriculture Victoria
  • Western Australia: Biosecurity and Agriculture Management Act 2007 (WA), administered by the WA Department of Primary Industries and Regional Development

Sources