Family: Poaceae

Status: Listed as a Weed of National Significance (one of Australia’s top 20 weeds). Declared noxious in category W2 (must be continuously suppressed and destroyed) in all south coast Local Government Areas, except for parts of Bega Valley Shire where it is too well established for this to be feasible. In these areas it is in category W3.

Description:
A tussock grass (to about 0.5m) with very fine bright green leaves less than 1mm wide, held very erect when young, and spreading in larger plants. Older leaves and whole tussocks in winter have a characteristic bleached appearance. Long, branched seed heads weep over to the ground around the tussock. The tiny seeds are enclosed in reddish purple structures called glumes, giving the whole plant the appearance of a large pink cushion when flowering. The seed itself is straw coloured and almost round, with a fine thread-like awn attached off-centre at one end.

Preferred habitat and impacts:
Serrated tussock is most invasive in over-grazed pasture in dry areas, but it will readily invade any sort of grassy vegetation, and even spread into forest adjacent to infested pasture. It can build up to high density eliminating most other plants.
Individual plants are long-lived and seed remains viable in soil for more than 13 years. Dense stands produce a serious fire hazard.
Serrated tussock has no feed value. Its fibre content is so high that stock are unable to digest it, and animals forced to graze it may eventually starve to death. It therefore reduces stock carrying capacity of pasture, as well as being one of the worst potential environmental weeds of remnant grassy native vegetation of farming areas.

Dispersal:
The entire seed head snaps off and blows around like a tumbleweed, to collect against fences and other obstructions. It is very light, and can be carried many kilometres on the wind. Seed can also stick to clothing and animals, and is spread in manure of stock feeding on infested pasture, in contaminated hay and in mud on vehicles.

Look-alikes:
Many native grasses have some points of similarity with serrated tussock:

• Poa or silver tussock (Poa labillardieri) is most commonly confused with serrated tussock, just because it is a large tussock, whose leaves feel serrated when rubbed with the fingers from top to bottom. The leaves of many grasses feel like this, and it is not diagnostic for serrated tussock.. Poa tussock also tends to grow in large stands, particularly in wet areas or on sheltered (south-facing) slopes. Unlike serrated tussock, it has tall erect seed heads which persist on the plant after the seed has fallen. The young heads are purple, not red or pink, and the seeds have no awn.

• Blown grass (Agrostis avenacea) and panic (Panicum effusum) have seed heads which snap off and blow around, but both of these have quite wide leaves, and neither have seeds which appear red. The seeds of panic are shiny and millet-like, without an awn. Those of blown grass do have an awn, but it is attached to the middle of the back of the seed, not at the tip. Magnification may be needed to see this.
• Corkscrew grass (Austrostipa scabra) can look very similar when not in seed to a young serrated tussock plant, as it has the same erect leaf growth and very fine foliage. Corkscrew grass has large awned seed, whose awns twist on maturity to produce a spiral effect up the seed head. However, like many native spear grasses, when the seed is young it may be red. The diagnostic feature for corkscrew grass is the erect, not trailing, seedhead which persists on the plant after the seed has been shed. Each individual seed is long and slim in shape, with the awn attached centrally at the tip.
• A small native poa tussock (Poa meionectes and possibly other species) also has fine erect bright green foliage, but like corkscrew grass it has erect, not trailing, seed heads which persist on the plant after seed has been shed. The young heads are purple, not red or pink, and the seeds have no awn. If trying to distinguish young plants with no flowering or seeding parts, it will be necessary to resort to checking the ligule. This is a small flap of tissue which is located at the junction of each leaf blade and the stem from which it arises. In serrated tussock the ligule is a small white flap about 1mm long, which is visible to the naked eye, sticking up at the leaf junction when the leaf blade is pulled back away from the stem. In the most similar looking Poa species the ligule is so short it is not visible to the naked eye. If viewed with magnification it is a very short flap which is hairy on the back, and not white.

Control:
Control before plants produce seed, or if too late bag seed and burn it. For small infestations, dig out plants and turn upside down, or suspend on other vegetation to dry out so that roots are not in contact with the soil. If spraying, use of a selective herbicide is preferable, since it minimises disturbance to other vegetation.
In pasture, it is important to maintain other pasture plants in vigorous condition, as serrated tussock seedlings are not very competitive in dense pasture. Control of rabbits, and of stock grazing pressure, is crucial.