Chilean needle grass is a perennial (long-lived) tussock-forming grass growing to 1 metre in height. The leaves are 1 to 5 mm wide, flat and strongly ribbed on their upper surface, with leaf edges that are rough to touch.
The flowering seed heads are a distinctive purplish colour and the seeds are very sharp at the point. Chilean needle grass flowers mainly from September to December but can flower year round. Seed is formed about one month after flowering and most seed has been dropped by February. Seeds mainly germinate in autumn and spring.
Spread is by seed. In addition to the normal flower (panicle) seeds, Chilean needle grass produces hidden seeds which are formed in the nodes and bases of the flowering stems. These 'stem seeds' are self-fertilised and account for about one-quarter of total seed production. They enable the plant to survive despite grazing, slashing and fire.
Chilean needle grass seeds can persist in the soil for many years even if further seed input is prevented. The seeds are spread by farm machinery, clothing or livestock, by road-side mowing and earth-moving equipment, and by floodwaters.
Spread of Chilean needle grass
- Chilean needle grass panicle seed is large and heavy and will not travel very far in the wind, maybe only a few metres.
- Seed spread is facilitated by the long, twisting awn and the sharply pointed seed head which together allow the seed to penetrate and 'burrow' into animal coats, fleece and clothing.
- Chilean needle grass seed can also be carried in mud on the hooves of livestock, machinery and implements, on vehicle tyres, in contaminated hay and on firewood.
- Chilean needle grass panicle seed can be dispersed by water along creeks and drainage channels.
Avoid the introduction of Chilean needle grass
- Preventing the invasion of Chilean needle grass is the cheapest and most effective means of control.
- Learn to identify Chilean needle grass, regularly check for it and act immediately to remove it.
- Regularly monitor known Chilean needle grass infested areas.
- Appropriately dispose of any panicle seed collected.
- Encourage the growth of competition in infested areas.
- If possible avoid working in an area infested with Chilean needle grass until it has been controlled.
- Before undertaking control works confirm that the species you intend to control is in fact Chilean needle grass as the plant you are dealing with may be a native grass.
- Small infestations and isolated Chilean needle grass plants can be chipped out with a mattock preferably before the plants set seed. Ensure that the base of the plant and as much of the root as possible is removed.
- Do not chip out large patches of Chilean needle grass where a seed bank has built up: any soil disturbance will cause the germination of seeds.
- Chilean needle grass can be controlled with the application of a herbicide.