Background

Nassella tussock is extremely adaptable and grows in a wide range of habitats. It will displace other plant species.

Why is it a problem?

Nassella tussock is extremely adaptable and grows in a wide range of habitats. It will displace other plant species. A mature nassella tussock can produce up to 120,000 seeds which are able to disperse over long distances. Some nassella tussock seeds can remain in the soil for more than a decade. Seeds can be wind and water borne, carried via animals, human beings (on clothing), on machinery and in agricultural seed.

Nassella tussock is unpalatable to stock. If not controlled, shading caused by nassella’s drooping foliage and overgrazing of other species soon result in displacement of palatable pasture plants. Nassella was first recognised as a problem in the 1940s and in the 1950s some farmers were forced to abandon their properties because of it.

Nassella tussock is difficult to recognise and distinguish from other tussocks and sedges, both native and introduced. Nassella tussock is costly to eradicate.

How to identify nassella tussock

• Flower heads are purple and carried on slender stalks from October to December. They are erect when young and droop over leaves when mature.
• Seeds are small, oval and purplish-brown with a bristle at the tip. Nassella tussock is most obvious to the untrained eye when flowers or seeds are present.
• Leaves are bright green and upright in small plants, becoming duller and more drooping as plants mature. Leaf tips are whitish during winter. Leaves feel rough when rubbed from tip to base.
• Roots are deep, fibrous and matted, making even small plants difficult to pull out. Stem bases are whitish and separate easily like shallots. When squeezed, the base feels very hard.

Where does it grow?

Nassella will grow almost anywhere. It prefers sunny, dry sites with poor vegetation cover and light soil but as the seed is so easily dispersed, expect to find it in any situation.

Control

The easiest method to control small infestations is by grubbing. This should be carried out prior to flowering as once flowers are present, even if the plant is grubbed, the seed will still develop and remain viable. All roots should be removed from the ground and excess soil shaken off. Chemical application with a glyphosate product can be useful for dense infestations and should be applied during the growing season.

Under Canterbury’s Regional Pest Management Strategy, land occupiers must complete a control programme to prevent nassella tussock plants from seeding. The control is to be completed by the 30th of September every year for all parts of Canterbury, (except those areas as identified on the map below which are to be completed by the 31st of October every year).

Nassella tussock map