What does it look like?
Marram grass is a coarse, long‑lived grass that forms stiff clumps of upright stems up to 1.2 metres tall. It grows from a network of thick underground stems (rhizomes), which can spread sideways by up to two metres in six months. A single clump can produce around 100 new shoots each year.
The leaves are sharply pointed and blue‑green, growing up to one metre long. They are tightly rolled, giving them a narrow, cylindrical shape. The seed heads are also cylindrical and grow up to 30 centimetres long.
Marram grass spreads both by seed and vegetatively. Rhizomes can take root when buried, and seeds are spread by wind and water. Pieces of rhizome can survive being submerged in seawater, break off, and float on currents to establish new plants elsewhere.
Why is it a problem?
Marram grass spreads quickly and can cover large areas of sand dunes. It changes the natural shape of dunes, creating large, steep‑faced dunes that are different from those formed by native plants. These steep dunes are more prone to erosion, which can lead to coastal recession and the loss of nesting sites for beach nesting birds.
Native dune grasses like pingao and spinifex struggle to compete with marram grass because of its rapid growth and ability to trap sand.
Control methods
Begin control at windward end of infestation, or where native vegetation is best represented. To prevent rhizome movement, control at eroding sites and prevent physical damage of marram at other sites.
Physical control
Dig out (small infestations) and dispose of rhizomes at a refuse transfer station.
Herbicide control
- Spot spray: 520g/L haloxyfop-P-methyl (30ml/10L + crop oil) or glyphosate (125ml/10L + penetrant).
- 520g/L haloxyfop-P-methyl will kill spinifex and stunt pingao, so consider species present at the control site before spraying.
- If possible, spray after rain to minimise salt contamination of herbicide, especially when using glyphosate.
- Follow up required annually until eradicated. Begin control at windward end of infestation, or where native vegetation is best represented. To prevent rhizome movement, control at eroding sites and prevent physical damage of marram at other sites.
CAUTION: When using any herbicide or pesticide, PLEASE READ THE LABEL THOROUGHLY to ensure that all instructions and safety requirements are followed.
More information
Marram grass is originally from Europe and North Africa and was introduced to New Zealand over 100 years ago for dune stabilisation, property protection, and to prepare sand dunes for the planting of conifers. It was recorded as naturalised 1873.
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