Chilean needle grass (Nassella neesiana) is an invasive, introduced plant that has the potential to cause havoc on farm, and in our environment.
It is referred to as a “sleeper weed”, a plant species that reproduces quietly and slowly in the wild such that it largely goes unnoticed until something activates it at which time it ‘takes off’ and becomes invasive. Containment and prevention are essential before the plants infest other areas.
In New Zealand, Chilean needle grass is found in 15 of 16 regions – for now, the West Coast of the South Island has avoided it. Hawke’s Bay, Marlborough and Canterbury have considerable infestations of the weed. In these regions it is classed as a ‘Sustained Control’ plant in Regional Pest Management Plans, requiring landowners to control infestation and prevent spread in the region.
The weed is largely spread via movement of livestock, hay, fodder, pasture seeds, and farm machinery, and by wild animals and flood. Unlike some other weeds, the wind is not a major disperser.
The grass itself has sharp arrow-like seeds at the tip of the blade that can penetrate the hides of livestock, cause blindness, leach nutrients from pasture, and adversely impact farm production. If left unchecked, Chilean needle grass has the potential to cause the New Zealand pastoral sector millions of dollars in lost production. One study puts the figure at $1.16 billion.
From a wider environmental perspective, Chilean needle grass has a detrimental effect on biodiversity.
How can you spot it?
While present year-round, it is easiest to spot between November and March when flowering.
Chilean Needle Grass is an erect, tufted perennial tussock that can grow up to one metre in height when left ungrazed. The seeds have a hardened 8-10mm seed head (lemma), and a 60-70mm twisted tail (awn).
The seeds are light brown and have a “distinctive dart-like appearance”. The tip of the seed head is sharp and pointed and can penetrate skin and muscle. It also has backward facing hairs a corkscrew-like awn that makes it very difficult to remove once embedded in flesh or clothing.
Nassella Neesiana in the marlborough region - Karen McCallum
A review of the latest scientific literature, reports, and farmer practices
Earthquake Biosecurity Project and Chilean Needle Grass Action Group
Report
What should you do if you spot it?
If you’ve found Chilean needle grass on your land, stock, feed, or materials you will need to report it immediately.
To report suspected exotic land, freshwater and marine pests or exotic diseases in plant or animals, call 0800 80 99 66, or visit www.mpi.govt.nz and fill in the online report form.
MPI and your regional authority will then work with you to develop a tailored control programme. Early detection allows for prompt containment and control of the infestation.
Find out who your regional authority is with Stats NZ’s Geographic Boundary Viewer.
Prevention is essential
Biosecurity measures and vehicle hygiene are crucial as Chilean needle grass is largely spread spready by people, animals, machinery and equipment. The infestations in Canterbury and Hawke’s Bay were both attributed to stock and seed sourced from infested regions hundreds of kilometres away.
Look at the risk areas on your property:
- Pathways: how can it get to your property?
- Vehicle hygiene and farm biosecurity practices
- Habitat: Chilean needle grass typically grows in dry, sunny areas.