Pencil willow

Native to South America and Mexico, pencil willow is a fast-spreading tree that invades native bushland and has an aggressive root system. It was once widely planted as a garden ornamental in Queensland. Pencil willow is now found from Cairns in north Queensland to Nowra in New South Wales. All species of willow are listed as Weeds of National Significance.

Pencil willow is a restricted invasive plant under the Biosecurity Act 2014.

Scientific name

Salix chilensis, syn. S. humboldtiana

Other names

Chilean pencil willow, Chilean willow

Description

  • Large, upright tree up to 15m tall.
  • Bark is smooth on branches, slightly fissured on trunk.
  • Twigs are brown to red.
  • Leaves are 15cm long, 1cm wide, do not drop entirely in winter.
  • Catkins (flowers) are male.

Habitat

  • Prefers light to medium, moist, well-drained soils.

Distribution in Queensland

  • Found along Queensland coast from Cairns to New South Wales border.

Life cycle

  • Flowers in spring.

Impacts

Environmental

  • Invades native bushland along banks of rivers and creeks.

Economic

  • Damages footpaths and drains with aggressive root system.

How it is spread

  • Spreads from broken twigs taking root downstream.
  • Easily broken branches provide material for vegetative spread.

Control

Effective control can be achieved by combining mechanical and herbicide treatments or by herbicide treatment alone. Choose control methods to suit your particular situation. All treated areas must be periodically checked and any regrowth treated, or initial treatment efforts will be wasted. Follow-up must be undertaken to ensure a successful control program.

Mechanical control

  • Cut down individual trees.
  • Burn all stems and braches (if permitted) as they can regrow into new trees

Herbicide control

Cut stump treatment
  • Cut stems horizontally as close to ground as possible and immediately (within 15 seconds) swab or spray cut surfaces and associated stem with herbicide mixture.
Stem injection treatment
  • Make axe cuts at 5-7cm intervals all around stem (or stems), allowing undamaged bark between cuts.
  • Make cuts below first branch and at an angle of approximately 30 degrees to stem. Immediately inject up to 1mL of herbicide solution per cut, allowing solution to cover cut surfaces on both bark and tree.

See the WONS willow management guide for herbicide control and application rates.

Biological control

  • No known biological control agents.

Legal requirements

  • Pencil willow is a restricted invasive plant under the Biosecurity Act 2014.
  • It must not be given away, sold, or released into the environment without a permit.
  • The Act requires everyone to take all reasonable and practical steps to minimise the risks associated with invasive plants and animals under their control. This is called a general biosecurity obligation (GBO).
  • At a local level, each local government must have a biosecurity plan that covers invasive plants and animals in its area. This plan may include actions to be taken on certain species. Some of these actions may be required under local laws. Contact your local government for more information.

More information