Chilean rhubarb

What does it look like?

Chilean rhubarb is a large, clump forming, rhubarb-like herb with large prickly leaves that can reach up to 2.5m tall. In winter, it dies back to large creeping stems and large, sausage-like flower spikes that are up to 1m tall. The spikes are covered in little flowers that are followed by tiny orange fruits.

In New Zealand, Chilean rhubarb mainly occupies damp sites on wetland and riparian margins, coastal cliffs, moist banks, and disturbed sites.

It often grows in light shade. It is scattered throughout New Zealand but is most common in high rainfall areas such as South Taranaki and Westland. It can be found occasionally in pasture, wetlands, riverbanks and forests.

Why is it a problem?

• Chilean rhubarb is extremely tolerant of salt, a wide variety of soil conditions, and very wet swampy sites and seasonally wet ground. It produces abundant fruit, which are dispersed by birds, and forms dense patches that exclude virtually all other plants.
• Chilean rhubarb produces large amounts of viable seed. Once established, infestations can increase in size from the massive, spreading roots and it also grows readily from any stem fragments which break off the plants.
• The seeds of Chilean rhubarb are spread by birds and water. Seeds and rhizomes (roots) are also spread deliberately by humans (for ornamental purposes and inadvertently in garden waste and soil). Stem fragments can break off plants and tumble-down steep slopes or be transported by water.

Control methods

Physical control
All year round: Pull out seedlings; Dig out individual plants or small patches - ensure removal of all rhizome fragments and flower/seedheads and dispose of these at a refuse transfer station.

Herbicide control

• Cut and paint (during spring): Cut off the leaves and paint the stalk stumps with picloram gel or glyphosate (250ml/L). Or,
• Spray (full leaf and actively growing): glyphosate (10ml/L knapsack).
• CAUTION: When using any herbicide or pesticide, PLEASE READ THE LABEL THOROUGHLY to ensure that all instructions and safety requirements are followed.

Related links

• Check Clean Dry
• Invasive Species Compendium
• New Zealand Plant Conservation Network
• NZ Flora
• Unwanted Organisms Register
• Weedbusters
• NPPA and the control of weeds | NZ Government