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Serrated tussock
status: Serrated tussock (Nassella trichotoma) is listed as noxious in class 4 in all LCAs of the Southern Tablelands and South East Region. It must be controlled in accordance with local management plans published by each LCA. Because it is listed in a notifiable class (1, 2 or 5) somewhere in NSW, this species cannot be propagated or sold anywhere in the state.
DescriptionTussock grass to 0.5m with erect bright green rolled leaves less than 1mm wide, with a 1mm long hairless white flap (“ligule”) where the leaf joins the sheath (pull the leaf back from the stem to make it visible). The long, branched seed heads can weep to the ground. The young seeds are enclosed in a red sheath, giving the flowering plant a pink fluffy look. The seed is tiny and almost round with a fine thread-like awn attached off-centre at one end.
Most aggressive in over-grazed pasture but it will invade any sort of grassy vegetation and adjacent bush. It has no feed value and reduces stock carrying capacity as well as reducing biodiversity in native vegetation.
DispersalWind. The entire seed head snaps off and can blow long distances, often piling up against fences (see photo 2). In the gut of stock, on vehicles and by water.
Look-alikesNatives, blown grass (Lachnagrostis filiformis or Agrostis avenacea as it was formerly called) and hairy panic (Panicum effusum) have seed heads which snap off and blow around, but both have wide leaves (to 5mm or so), and neither has the red appearance of the seed heads. Corkscrew grass (Austrostipa scabra) and native poa tussocks (Poa species) can look similar with the same erect leaf growth and very fine foliage but they have erect seed heads which stay on the plant after seed has been shed. The ligule of most Poa species is invisible to the naked eye and under magnification it is hairy on the back.
ControlDig prior to seeding, spot or boom spray. For large infestations cultivate or spray and direct drill to establish competitive pasture species. It is important to maintain other pasture plants in vigorous condition as serrated tussock seedlings are not very competitive in dense pasture. However, applying fertiliser to established infestations is unlikely to help as mature serrated tussock plants respond well to fertiliser. Only the seedlings are susceptible to competition. Control of rabbits and of stock grazing pressure is crucial. Reafforestation may be a long-term solution.
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