Nassella tussock

Common name: Nassella tussock
Botanical name: Nassella trichotoma
Management category: Eradication

Nassella tussock is native to South America and thought to have been accidentally introduced to New Zealand in the late 1800s. Because the plant is difficult to identify from native tussocks, it was able to spread under the radar. By the 1930s/1940s it had formed monocultures of grass in farms in Marlborough and North Canterbury. The Nassella Tussock Act was passed in 1946 which allowed for central government to fund the astronomical costs associated with control programmes. 

Why is it a pest?

  • Overruns desirable pasture.
  • It’s difficult to control, and if left, will create a monoculture.
  • Reclaiming areas that have been infested with Nassella is a long and expensive exercise.
  • Stock cannot digest this grass, and it forms balls in their stomachs.
  • It has poor nutritional value and can cause ill-thrift and potentially death.
  • It is spread by wind dispersed seed which can travel up to 16km from the ‘mother’ plant.

Where is it found?

Nassella tussock has one known location in Ōpōtiki for the Bay of Plenty region. It likes poor or dry pasture, open areas and coastal areas.

What does it look like?

  • Dense tussock perennial grass with fine, wiry leaves which are rough to the touch.
  • Leaves have a blue-green tinge with blonde leaf tips.
  • Flower head is a loose cluster of subtle purple spikelets from October to December.
  • Seeds are red/pink and visible from January.
  • Seeds have a rough coating which allows them to attach to wool or clothing.

What are the rules?


Nassella tussock is an eradication pest. Eradication pests are present in the region but are limited in their size or extent of infestation. The eradication of these organisms is a feasible and cost-effective solution. The Bay of Plenty Regional Council is responsible for the control of Nassella tussock.

Please contact the Bay of Plenty regional Council for advice if you have found Nassella tussock.

How do you get rid of it?

The Bay of Plenty Regional Council is responsible for the control of Nassella tussock. Please contact us and we will come to control it for you.