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Nettle tree (Celtis australis)

Nettle tree is cultivated in parts of Australia as a shade and street tree, but it can become naturalised and invade woodlands, river margins, urban areas and pine plantations. Its fruits are spread mainly by birds, allowing seedlings to establish beyond planted areas.

Key facts

Type: Weed, tree.

Native to: Europe, North Africa and Turkey.

Established in: NSW, ACT, VIC, SA.

Other names: Southern Nettle Tree, European Hackberry, Lote-tree, Honey-Berry.

Identification

  • A deciduous tree usually growing to 15 m tall, sometimes reaching 20 m, with a broadly rounded crown and dense foliage.
  • Its grey-brown bark becomes flaky with age, and older trunks may be fluted or slightly buttressed.
  • Leaves are lance-shaped to oval-lance-shaped, finely toothed, rough to touch above and pale grey-green with soft hairs below.
  • Small greenish-yellow flowers appear in spring, and the leaves turn creamy-yellow in autumn.
  • Round, fleshy fruits about 10 mm across turn from yellow-green to orange, indigo, purple and nearly black as they ripen.
  • Look-alike: It resembles other introduced Celtis species; distinguish it by its toothed leaves, few-flowered clusters, rough upper leaf surface, pale softly hairy lower surface and purple-to-black fruit.

Where it grows

In Australia it is cultivated in the ACT, New South Wales, Victoria and South Australia, and occurs in gardens, parks, roadsides, wasteland and occasionally natural vegetation, including woodlands, river margins and pine plantations.

Why it matters

  • It can invade woodlands, urban areas, river margins and pine plantations.
  • Seedlings can establish in gardens and parkland and, if left, become large woody weeds.
  • It is not a known agricultural weed, although it may self-seed around mature plants.
  • Its pollen is moderately allergenic.

How it spreads

  • It reproduces mainly by seed and may also sucker.
  • Birds spread the seed, and fruit bats may also spread it.
  • It is sold at nurseries and garden centres.

Control options

  • For isolated small seedlings, hand-pull or dig them up; this is practical only for a small number of plants.
  • Larger trees can be cut down, with the stump dug up and removed.
  • Registered herbicides can be applied using cut-stump, basal-bark or stem-injection methods; the choice depends on the site, tree size, access and personal preference.
  • Avoid moving fruit into uninfested areas when removing mature trees.

Hygiene and washdown

  • When removing mature trees, avoid carrying fruit into uninfested areas.
  • 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: Not a priority weed. Not a state or regional priority weed in NSW. 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: Not declared. Not on the NT A to Z weed list, and Weeds Australia does not list it as declared in the NT. Check the NT declared weeds list before moving or planting it.
  • Australian Capital Territory: Declared pest, prohibited. It is a declared pest throughout the ACT. Dealing with it, such as selling, moving or keeping it, is prohibited.

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.

  • 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
  • South Australia: Landscape South Australia Act 2019 (SA), administered by the regional landscape board

Sources