Giant reed
Poaceae - Arundo donax

What does it look like?

Giant reed is a bamboo-like grass that can grow to 8m tall. It has a very strong, dense root structure that spreads outwards and downwards. Leaves are bluish-green or white-striped, and fluffy seedheads grow at the tops of the stems. 

Giant reed can grow on a range of soil types, but prefers areas where the soil does not dry out completely; such as moist forests, shrublands, roadsides, wastelands, domestic gardens, and river/stream/lake edges. It can also tolerate semi-saline conditions growing on the banks of estuaries and coastal areas.

Why is it a problem?

Giant reed is a very fast-growing, aggressive species that can out-compete native plants and form dense stands.  It can alter ecological and successional processes and change habitats. It is tolerant to different climates and can survive and grow at almost any time under a wide variety of environmental conditions. The horizontal rhizomes (roots) of giant reed allow it to grow outwards to form large colonies, and it also grows from plant fragments. 

Control Methods

Physical control

  • Smaller clumps can be dug out by hand and disposed at a refuse transfer station or burnt.

Herbicide control

  • Cut off and spray regrowth with 3% glyphosate (300ml per 10L water). Respray for up to 4 years.
  • Cut down close to ground and spray the regrowth with 150ml/L Haloxyfop + 50ml crop oil/10L before it reaches 60 cm. Continue respraying at under 60 cm until regrowth ceases. This normally requires 4-6 treatments.

Minimise herbicide contact with the soil and other vegetation as Amitrole is non-selective, residual and corrosive.

  • Stray emergent shoots can be cut at ground level and injected with 10 ml of undiluted Amitrole into each stem.

Follow up frequently to check for regrowth.

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