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White poplar (Populus alba)

White poplar is an introduced ornamental tree that has become naturalised in parts of Australia, especially on poorly drained ground. Its root suckers can spread beyond plantings and form dense growth that competes with other vegetation.

Key facts

Type: Weed, tree.

Native to: Temperate Eurasia and North Africa.

Established in: NSW, ACT, VIC, TAS, SA, WA.

Other names: White Fastigiate Poplar, Silver poplar, Silver-leaved poplar.

Best time to act: Look for plants year-round and plan treatment when plants are actively growing, then revisit the site to find and control suckers.

Identification

  • A deciduous tree that can grow to 20 m, with an erect trunk and spreading lower branches.
  • The bark is smooth and pale grey when young, developing dark furrows with age.
  • Leaves are usually 3–9 cm long and 2–6 cm wide, with a pale, often whitish felted underside.
  • Purplish catkins are 3.5–6 cm long and elongate as the fruit develops; the capsules are about 3 mm long.
  • The cultivar 'Pyramidalis' has a narrower, more upright habit than the usual form.
  • Look-alike: Other poplars can have similar leaves and catkins; the pale, felted underside of white poplar leaves is a useful identifying feature.
  • Look-alike: The narrow, upright 'Pyramidalis' form may resemble other columnar poplars, but its leaves and pale bark help distinguish it.

Where it grows

In Australia it is cultivated and frequently naturalises by suckering, particularly in poorly drained ground.

Why it matters

  • Root suckers can spread out from planted trees and establish new stems.
  • Dense stands can compete with other plants for space, light and resources.
  • Its ability to naturalise can make it difficult to contain where it has been planted.

How it spreads

  • Root suckering is a prominent means of spread and can produce new stems around established trees.
  • Seeds may also be dispersed from fruiting trees, while movement of soil containing roots or root fragments can spread the plant to new sites.

Control options

  • For small plants, remove the whole root system where practical, and check the site for regrowth; broken or remaining roots may produce suckers.
  • For established trees, use an appropriate method such as cut-stump treatment or stem injection with a herbicide registered for the situation, following the product label and local advice.
  • Do not rely on felling alone, as stumps and roots may reshoot; monitor and treat regrowth until control is achieved.
  • Check with the relevant state or territory biosecurity agency or local council for local control advice and any reporting requirements.

Hygiene and washdown

  • Clean soil and root fragments from machinery, tools, footwear and vehicles before leaving an infested site, and avoid moving contaminated soil.
  • Dispose of removed roots and plant material securely so they cannot take root or be spread to another site.
  • 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
  • Tasmania: Biosecurity Act 2019 (Tas), administered by Biosecurity Tasmania
  • South Australia: Landscape South Australia Act 2019 (SA), administered by the regional landscape board
  • Western Australia: Biosecurity and Agriculture Management Act 2007 (WA), administered by the WA Department of Primary Industries and Regional Development

Sources