[Bombala Times 14 Oct, 2010] -- SERRATED tussock (Nassella trichotoma) is one of Australia's worst perennial grass weeds invading pastures, native grasslands and urban areas, with an amazing ability to disperse its seeds over great distances. A native of South America, it is a plant that has great capacity to survive and further expand its spread. It can tolerate extremes of temperature, low rainfall and low soil fertility. With its prolific seed production and ability to spread by wind, livestock, machinery and transport networks it is well suited to rapidly advance over new areas in the temperate zone, colonising bare patches of ground and changing landscapes forever.
"Serrated tussock is a force to be reckoned with," said Mitchell Clapham, Chairman of the Serrated Tussock Working Party for NSW & ACT.
"It has the ability to cause a greater reduction in carrying capacity than any other species in Australia, reducing pastures that carry 7 - 15 dse per hectare to a carrying capacity of only 0.5 dse."
"Add to this the ability of a single mature plant to produce more than 100,000 seeds per year with light seed heads able to travel great distances by wind, perhaps up to 20km, and you have a serious problem."
While wind is the primary natural method of seed dispersal in the serrated tussock plant, human activity now plays a significant role in its spread.
Serrated tussock seed heads can be caught and transported by vehicles, machinery, tractors, implements, spray units, mowers and slashers.
Its seeds attach to the fleece and fur of livestock and other animals, and may also be picked up in mud on the animals' hooves.
Livestock will generally avoid eating serrated tussock, however if they do graze it while in seed, the animals can spread the seed through their droppings.
The seed can survive in the gut of ruminant animals for up to 10 days making it possible for serrated tussock to be spread long distances.
Serrated tussock seed can contaminate crops, hay, silage, grain and seed. Movement and use of contaminated produce can lead to the development of new infestations as can the movement of soil from an infested area.
There are some simple steps all land managers can take to help prevent the spread of serrated tussock:
Learn to identify serrated tussock, regularly check for it and immediately remove it.
Buy certified seed and avoid purchasing hay or produce from contaminated areas.
Stock grazed on seeding serrated tussock should be placed in a holding paddock for 10 days before being moved into a clean paddock.
Desirable vegetation can be used as a barrier to effectively reduce wind dispersal of the seed. Rabbit proof fencing can also help catch tumbling serrated tussock seed heads.
One of the first steps in taking control of serrated tussock is to stop its spread. This requires a concerted effort.
Be vigilant - watch for new serrated tussock germinating and act quickly. For mature plants or dense infestations concentrate on stopping seeding and containing the infestation.
And remember, your district agronomist or weeds officer is always available to help.
For further information contact Clare Hamilton on 0428 791 359 or