Chilean Needle Grass, named for its sharp pointed seed, is regarded as one of the worst weeds in Australia. Chilean needle grass is a perennial tussock grass which grows in dense clumps up to 1m in height. It is highly drought resistant, can cause injury to livestock, contaminates wool and reduces biodiversity by outcompeting native species.

Image: Rachel Betts, New England Weeds Authority Biosecurity Officer, looking at Chilean Needle Grass in Armidale.     

As the name suggests, Chilean needle grass is native to South America. It has been known to exist in Australia since the 1930’s but due to its relatively slow spread has only recently been recognised as a serious weed. The issue lies in how difficult it is to control. Chilean needle grass can produce more than 20,000 seeds per square metre. The seedbank can persist for many years even when further seeding is prevented. An unusual feature is that in addition to its distinctive purplish seedhead, it produces hidden seeds which form at nodes along the stem and at the base of the plant.

Once established, Chilean needle grass is difficult to manage. The best outcome is early identification and physical removal before the plant can get established. Once a high level infestation is established a combination of control approaches will need to be used over a number of seasons including herbicides and grazing management. Apply herbicides any time of the year when Chilean Needle Grass plants are green, actively growing and not moisture stressed. Control scattered infestations first and work back to denser infestations. Always follow up treatments with further spot spraying or chipping, as some plants may be missed and new seedlings will always emerge. Regularly monitor treated areas for the emergence of seedlings. In the bare ground created by spot spraying, scatter pasture seed and fertilizer to promote ground cover and competition with Chilean Needle Grass seedlings. The use of Flupropanate based herbicides as per the label will also control Chilean Needle Grass.

Preventing the spread of seed is the key to preventing further spread of Chilean needle grass. In known infestations we ask that great care is taken when moving stock or machinery to other areas.

For help with weed identification and management, please contact the NEWA Biosecurity Officers (Weeds) on 02 6770 3602, call into the Armidale office at 2/129 Rusden Street, or the Inverell office at 144 Otho Street, follow their Facebook page or visit www.newa.com.au.

Images: supplied by Rachel Betts, NEWA
Below left: Chilean Needle Grass Seedhead
Below right: Chilean Needle Grass Seed close up.