Giant Rhubarb

Family:
Gunneraceae
Origin:
Brazil

General description

Clump-forming perennial herb < 2.5 m tall, < 4 m wide. Rhizomes are stout. Leaves are very large and prickly. Flowers are minute and borne on dense, closely branched conical panicles < 1 m long. Drupes contain a single ovoid, flanged seed.

What you need to know

To help protect our environment, from 1 September 2021, you:

  • will not be allowed to breed, distribute, release or sell giant rhubarb within the Auckland region.
  • will not be allowed to plant giant rhubarb within the Auckland region, unless you are transferring an existing plant on your land to another location within the boundaries of the same property.
  • must destroy any giant rhubarb on land that you occupy if it has been planted in breach of the above rules and you are directed to do so by an authorised person.

Riparian margins, wetlands, coastal areas, cliffs.

Sets seed. Vegetative spread from rhizome fragments.

Competes with native vegetation and prevents native seedling establishment. Reduces native biodiversity in riparian margins, wetlands, coastal areas and cliffs.

Site Management

Follow up treated areas 3 times per year. Encourage natural regeneration of native plants or replant treated areas where possible after 2-3 treatments to establish dense ground cover and minimise reinvasion.

Recommended approaches

Physical control

Method: Dig out

Plant parts requiring disposal: Seeds and rhizomes

Disposal options: Remove to greenwaste or landfill

Biocontrol

Biocontrol is currently not available for this species.

Community agrichemical control recommendations

No qualifications
Cut stump and paste freshly cut base of stems with double strength glyphosate gel
or
Cut stump and spray freshly cut base with 200ml glyphosate green per 1L of water

Certified Handler/Experienced agrichemical user
Foliar spray with 200ml glyphosate green per 10L of water and 20ml penetrant

Safety notes

Plant has spines.

CAUTION: When using any herbicide or pesticide please read the label thoroughly to ensure that all instructions and safety requirements are followed.

Similar species

Chilean rhubarb
Gunnera tinctoria

G. tinctoria is a smaller plant. The inflorescence is shorter and more compact. Another difference is between scales which are found at the base of the leaves and inflorescence. In G. manicata there is a prominent development of membranous "webbing" between the main lobes of the scale whereas in G. tinctoria this is not well developed and so the lobes are often almost free to the main rachis of the scale.

RPMP status


Whole region (Sustained Control)
Hauraki Gulf Controlled Area Notice pest
Giant rhubarb - Main species image