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About Chilean needle grass | Research on CNG | National Management | Upcoming Events | Feedback & Comments Manager's Fact Pack Part 1: The Weed and Its Impact Botanical Name The botanical name of Chilean needle grass is Nassella neesiana (Trin. & Rupr.) Barkworth. A synonym of Nassella neesiana is Stipa neesiana Trin. & Rupr. Throughout Australia and New Zealand N. neesiana is commonly known as Chilean needle grass. In the United States of America it has been called Uruguayan tussock grass, and in Argentina the common name is fletchilla, meaning 'little dart', after its needle sharp seeds. Distinguishing Features The distinguishing features of Chilean needle grass that allow for positive identification include:
How to identify Chilean needle grass
Iaconis, L. and Faithfull, I. 2003. Weed Watch Warning: Chilean needle-grass Nassella neesiana. Under Control Pest Plant and Animal Management News. No. 23. Department of Primary Industries, Frankston, Victoria. Page top Key biology The key biological features that make Chilean Needle Grass so successful include:
Chilean needle grass is an erect, tufted perennial tussock forming grass. All stipoid grasses naturalised in Australia, including Chilean needle grass, are cool season perennials, which means they grow during autumn and winter and flower and set seed during spring and early summer. In favorable conditions, plants can produce flowering stems in a year from germination. Germination: Seedlings emerge predominantly in autumn and spring, but emergence may also occur at other times of year when sufficient moisture is available. Panicle seed does not germinate readily, as the hardened lemma has to soften and break down before germination can occur. This may take 3 to 4 months, thereby delaying germination. It is, therefore, the cleistogenes that are usually the first seeds to germinate in autumn and spring. 'Gaps' in the pasture or other vegetation are required for germination to occur. However, once germination occurs, the survival of both seedlings and adult tussocks is quite high. Seed set: Peak flowering is between November to February. Chilean needle grass can produce large numbers of panicle seed during this time. In a dense, ungrazed infestation, panicle seed production ranges from 1,600 to 22,000 seeds per square metre. As well as the panicle seed, the stem nodes and base of the plant bear cleistogenes beneath the leaf sheath, which also account for a considerable amount of the total seed production (Gardener et al. 1999). Cleistogenes hidden at the base of the plant allow this weed to reproduce, even if flowering has been prevented or most of the plant has been destroyed. Seed life: The persistence of Chilean needle grass is aided by a large, long-lived seedbank. Even without the input of additional seed, the seedbank declines very slowly over may years. Gardener et al. (1999) tells of a study in which the seed bank of Chilean needle grass persisted for more than three years without seed input. During this time, the decline in viable seeds was noted and these data were fitted with an exponential decay curve that estimated that an initial seedbank of 7,100 seeds per square metre would take 12.4 years to reach 10 seeds per square metre. Seed dispersal: Panicle seed has a needle sharp tip and a long awn that readily attach to animals, machinery, and clothing. Gardener et al. (1999) reports that in two experiments, unshorn sheep still carried some Chilean needle grass seed (at least 10 percent of the original seed) in their wool after more than five months. In this time, there would have been ample opportunity for dispersal over large distances by stock movement. Both the panicle seeds and cleistogenes contaminate soil and hay. Where occurring in riparian areas, floodwaters can also act as a mechanism to long-distance dispersal. Tolerance: The tenacity of Chilean needle grass is also reflected in its wide ecological amplitude. Liebert (1996) comments that it often establishes in damp depressions such as drainage lines and roadsides, which then radiate into drier grassland. It is, therefore, tolerant of soils or sites that are subject to seasonal waterlogging. When established, the robust tussocks can withstand heavy grazing, fire and drought. Competition: Chilean needle grass is highly invasive and competes with desirable pasture plants. Due to its unpalatability when flowering, selective grazing can promote the dominance of Chilean needle grass. Under grazing, Chilean needle grass tiller profusely, forming dense clumps that exclude other pasture species. McLaren et al. (1998) report that Chilean needle grass is much more invasive in indigenous kangaroo grass (Themeda triandra) dominated grasslands than serrated tussock (Nassella trichotoma). In trial plots, Chilean needle grass has not only invaded areas of kangaroo grass but has also choked out serrated tusoock. Carr et al. (1992) rated N. neesiana as a 'very serious' environmental weed of lowland grassland, grassy woodland and outcrop vegetation. It has further been described as potentially the worst environmental weed of critically endangered indigenous grassland ecosystems in south-eastern Australia (C. Hocking personal communication). Page top Where Chilean needle grass grows Chilean needle grass prefers temperate regions of south-eastern Australia, where it establishes on more fertile soils. The potential distribution of Chilean needle grass in Australia has been estimated to be more than 41 million hectares. It can dominate pastures, indigenous grasslands and roadsides. Climate: Chilean needle grass establishes well in temperate regions of south-eastern Australia that receive more than 500 mm of annual rainfall. In drier locations, the plant may survive in favorable microclimates such as along waterways. The climate-matching program CLIMATE, predicts that over 41 million hectares of south-eastern Australia are climatically suited to invasion by this species.
Soil: In Australia, Chilean needle grass commonly establishes on more fertile soils, particularly volcanic soils. It proliferates on basaltic soils of the New England Tablelands and on the Volcanic Plain of Victoria. It is also found on granite soils around Tenterfield and Emmaville on the New England Tablelands, on rich clay at Lucindale in South Australia and on alluvial soils in outer Melbourne. Chilean needle grass often establishes in damp depressions, such as drainage lines and roadsides that then radiate into drier grassland. It tolerates drought, as well as soils or sites subject to seasonal waterlogging. Plant associations: Chilean needle grass is a very serious weed of lowland grassland, grassy woodland, riparian vegetation, and rock outcrop communities. Themeda triandra (kangaroo grass) is the dominant indigneous species in grassland ecosystems, however N. neesiana is much more aggressive than T. triandra and can dominate where invasion has occurred. Land use: Chilean needle grass dominate large areas of highly productive pastures on the Northern Tablelands of New South Wales and on the Volcanic Plain of Victoria. It is also common along roadsides, particularly in Victoria, which form corridors for dispersal. Page top Spread history Chilean needle grass was first noted in Melbourne, Australia in the 1934. It is now well established throughout Victoria, New South Wales, Australian Capital Territory, with isolated infestations in South Australia and Queensland. Man has been the most significant vector responsible for the dispersal of this weed. Hygiene is consequently important if further spread is to be prevented. Chilean needle grass was introduced from South America where it occurs in Argentina, Bolivia, Chile, Ecuador, Southern Brazil and Uruguay. The earliest known Australian collection was from the Melbourne suburb of Northcote in 1934. In New South Wales, the earliest collection was from Glen Innes on the New England Tablelands in 1944. Chilean needle grass also naturalised in South Australia where it was first recorded from Lucindale in 1988. There is one record of the plant occurring in Felton, Queensland, which was made in 1998. A small infestation was also recently recorded in Hobart, however has since been eradicated, with no other recorded infestations in Tasmania. The plant has not been recorded in Western Australia. It is thought that Chilean needle grass was imported to Australia as a contaminant of wool or fodder from South America. This is due to it being reported as occurring near factories in Europe that processed wool and hides from South America. Humans are responsible for most of the long-distance dispersal, mainly through lack of equipment and material hygiene and by the movement of livestock from infested areas to clean areas. Along Australian roadsides where Chilean Needle Grass can proliferate, slashers are frequently utilised by authorities to undertake fire management activities. Royal Melbourne Institute of Technology (RMIT) is undertaking a project to develop new slasher designs in order to reduce dispersal of propagules into 'clean' areas. People working in areas with Chilean needle grass must be sure to remove seeds from clothing and equipment when they leave. Movement of stock should also be regulated by land managers in order to minimise seed spread. Page top Impact of Chilean needle grass Chilean needle grass is a major threat to both conservation and agricultural lands. It is a vigorous competitor of both indigenous and pasture species, can be unpalatable to stock, contaminate agricultural produce, cause physical harm to animals and humans, and much more. The impacts of Chilean needle grass are one of the main reasons it has been proclaimed as an inaugural Weed of National Significance. The competitive ability and efficient reproductive mechanisms of Chilean needle grass have enabled it to dominate large areas of highly productive pasture on the Northern Tablelands of New South Wales and on the Volcanic Plain of Victoria. During warmer months, it produces large numbers of unpalatable flower stalks and very little leaf material, resulting in a severe reduction in available fodder. In fact, primary production has been reduced by as much as 50% in heavy infestations. The sharp seeds of Chilean needle grass have a natural twisting mechanism that cause seeds to lodge into fleece, skin, eyes and ears of livestock in response to changes in humidity. The result is vegetable fault in wool, abscesses in meat and holes in hides, thereby reducing the value of agricultural products. In New Zealand, seeds have been found to move through the skin and into the body muscles, causing abscesses and downgrading carcasses and even rendering them unsalable. The seeds are also known to cause discomfort to dogs and humans, thereby restricting human access in recreational and other areas. On conservation lands, Chilean needle grass is a very serious environmental weed that invades lowland grassland, grassy woodland, rock outcrop vegetation, and riparian vegetation. Chilean needle grass is potentially the worst environmental weed of indigenous grasslands in Victoria (C. Hocking personal communication). Chilean needle grass is much more invasive in Themeda triandra (kangaroo grass) dominated grasslands than is N. trichotoma (serrated tussock). Trials have shown that Chilean needle grass not only invades kangaroo grass dominated grasslands, but also chokes out serrated tussock. Chilean needle grass is invading extensive areas of rare indigenous grasslands, threatening both critically endangered communities, such as grassland plain communities, and species, such as the sunshine spider orchid (Diuris fragrantissima), and the nationally vulnerable rice flower (Pimelea spinescens). Page top
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