• Key characteristics
  • Biology
  • Impacts
  • Control
  • Further information

  • Erect, tufted perennial tussock which can grow up to 1 m tall when ungrazed
  • Drought tolerant and very competitive with pasture species
  • Seeds are approximately 7 cm long, with sharp, needle-like tips that can penetrate skin and flesh. The corkscrew-like awn helps force the seed through the skin and muscle. Seeds also have backward-pointing bristles which make them hard to remove once they are embedded
  • Leaves are bright green, 1-5 mm wide and up to 30 cm long. They roll inwards when plants are under drought stress
  • Leaves are covered with small erect hairs giving them a shaggy appearance. Upper leaf surface is strongly ribbed and leaf edges feel rough to the touch
  • Produces many tillers when grazed, forming dense tussocks that exclude other pasture species. Tillers are swollen at the base
  • In summer, before flowering, the plant appears lighter green than other grasses. However, it can be hard to identify and is sometimes confused with danthonia (Rytidosperma spp.)
  • Seed heads up to 30 cm long are present from mid-October to early January. When they first emerge they are reddish-purple in colour with long, light green awns (bristles).

Origin

  • Chilean needle grass originated in South America and was first identified in New Zealand in the 1920s
  • Since then the grass has spread to infest 600 ha in Hawkes Bay, 2800 ha in Marlborough and 300 ha in North Canterbury
  • It grows on dry north-facing hill country, forestry blocks, edges of farm tracks, river banks; around hay barns, sheep yards and power poles, fencelines and other places where stock rub themselves.

Life cycle

  • Chilean needle grass can thrive in both high and low fertility sites and under moderate to severe moisture stress
  • Seeds prolifically and builds up large seed reserves in the soil, making it hard to eliminate large populations. Normally 99% of the seeds in the soil seedbank are found in the top 2.5 cm of soil
  • Can reproduce by either cross- or self-fertilization, and some seeds are produced in unopened flowers near the base of the flower stem
  • Chilean needle grass may have the potential to spread to 15 million ha nationwide, mainly on the East Coast of both islands. In the absence of active management infestations may spread outwards at about 120 to 140 m a year.
Autumn and winter
  • During autumn and winter seeds, from the previous season and those in the soil seedbank, germinate and establish new plants.
Spring
  • Reproductive tillers are produced from mid-September until mid-October
  • By mid-November the main seeds heads are formed.
Summer
  • Between December and January the main seed heads become fully developed. Seeds are shed and fall into cracks in the soil or between the tillers of the parent plant. They can be carried to other sites by attaching to clothes, footwear, animals, vehicles, and farm machinery, as well as in soil or contaminated feed
  • After flowering, hidden flowers at the base of the flower stems produce flowers that never open but still produce viable seeds. These are held tightly to the base of the plant by a leaf-sheath and when the plant dies the leaf-sheath decomposes    and the seeds are released
  • Seeds still attached to the stems can be dispersed by wind, by attachment to livestock or in baled hay
  • These hidden seeds mature later than the main seeds and do not ripen until February but will remain on the stem until the plant material dies and decays
  • Even under hard grazing or mowing Chilean needle grass continues to produce seed from basal flowers.

Benefits

  • During winter and early spring Chilean needle grass can provide palatable, moderate quality fodder, suitable for cattle and sheep.

Impact on farming

  • Stock should be removed from affected areas between late October and March to avoid stock damage
  • Enforced containment measures can be restrictive and inconvenient
  • Successful control is difficult and expensive.

Impact on pasture

  • Chilean needle grass can outcompete and displace other pasture species. Its containment and control is both hard and expensive.

Impact on stock

  • Seeds of Chilean needle grass can contaminate wool and damage sheep pelts¸ as well as adversely affecting cattle, horses and even dogs, leading to considerable economic losses
  • Lambs are particularly vulnerable to damage: the seeds can even blind animals
  • During flowering and seeding periods the plant should not be grazed, and this effectively reduces the stock-carrying capacity of the grazing land.

Early eradication

  • Destroying the first few plants that appear on the farm can pay big dividends by saving on future costs. Pulling plants out and carefully putting them in plastic bags, before burning or very deeply burying them, is probably the best treatment for those first few. Take care not to spread the seed around.

Grazing

  • Grazing is not an effective method of control
  • Under hard grazing plants continue to produce seed from hidden basal flowers
  • When it starts to flower and seed its foliage becomes very unpalatable. Stock should not be allowed to graze as damage from the seeds is inevitable.

Mowing

  • Mowing is not an effective control method
  • Mowing before flowering can prevent seed head and stem-node seed production, but seed will still be produced from hidden basal flowers
  • Mowing should be avoided once the plant has flowered as it can spread the seeds
  • Mowing too early during development may encourage plants to produce more reproductive tillers
  • Mowing also reduces shading from other pasture species and this can encourage survival of Chilean needle grass seedlings.

Pasture species/cultivars

  • Establishment of new competitive pasture species such as cocksfoot can reduce the abundance of Chilean needle grass by shading it out
  • Successful establishment of new grasses requires applications of glyphosate in spring and autumn followed by direct drilling or shallow cultivation (5 cm) in autumn
  • A dense sward of sown pasture species in autumn/early winter will prevent Chilean needle grass seedlings from establishing
  • New pasture establishment may be required every 4-6 years to prevent Chilean needle grass displacing pasture species.

Forestry

  • Trees can form a dense canopy and shade out Chilean needle grass before the grass has properly established
  • In dry areas the trees take longer to form a dense canopy and should be planted more closely together than normal. It is important to use trees that provide heavy shade. Gums, for example, are not suitable.

Chemical control

  • Flupropanate (Taskforce®) is a selective residual herbicide for Chilean needle grass and nassella tussock
  • The length of residual control depends on the soil type and rainfall after application
  • Results to date have proved variable and studies are underway in Canterbury to assess its efficacy and selectivity in pasture
  • Non-selective herbicides like glyphosate (e.g. Roundup) or haloxyfop (eg Gallant) can be used for quick knock-down of plants just before seeding but have no residual effect unless combined with flupropanate. If used alone such herbicides will provide a good seedbed for Chilean needle grass seeds in the soil.

Biocontrol

  • There is no biological control agent available for Chilean needle grass at present although research is currently begin done in New Zealand, Australia and Argentina to find appropriate control agents.