Parramatta Grass (Sporobolus africanus).

Rat’s Tail is spread rapidly by vehicle traffic, wind and flood water. It grows rapidly, is frost and drought resistant, and produces around 80,000 seeds per plant.

After you read this, you will be able to:

• Identify Rat’s Tail.
• Know what conditions favour Parramatta Grass.
• Know the best options to control Tussock Grass.

Why is Parramatta Grass a Problem Weed?

• Is a weed in wet areas such like watered turf, roadsides and waste land.
• It emerges all year round when soil moisture and temperatures are suitable. Spring and Summer is when most seedlings tend to appear.
• Parramatta Grass produces large numbers of seeds, These readily disperse, and a soil seed bank can quickly build up.
• It is a long lived grass, and its seeds remain viable in the soil for a long time.
• Tussock Grass can grow in low rainfall areas. However, it is more common in areas with an average annual rainfall above 700 mm per year.

More information on common lawn weeds is in our weed ID chart. What they reveal about soil conditions is in our blog on indicator weeds.

Rat’s Tail or Parramatta Grass is an indication of soil compaction.

The distribution map for Rat’s Tail is courtesy on The Atlas of Living Australia.

How to Identify Parramatta Grass.

Category: Grass

Photosynthetic Pathway: Tussock Grass is a C4 grass weed.

Flower: The flowers are green or grey.

Height: Rat’s Tail grows to a height of up to 50cm.

Leaf length: The long and narrow leaf blades are up to 20 cm long.

Leaf width: The thin and elongated leaf blades are up to 6 mm wide

Reproduction: The seeds of Tussock Grass are spread via machinery and vehicles. When the seeds are wet they become sticky. They then stick to animals and clothes.

Parramatta Grass produces up to 60,000 seeds per square metre. Estimates of the soil seed bank have put it at up to 600 to 4,000 seeds/m2.

Even thought he seed is physically small it does not disperse by wind. Generally, most seed falls within 2 to 3 m of the plant.

Comments: Tussock Grass has very tough, smooth and glabrous, dark green leaves. You find these mainly around the base of the plant, and they are slender and stiff, with in-rolled margins. Where the blade meets the stem, the leaf sheath rolls around the stem.

Habitat:  Rat’s Tail mostly grows in areas with a moderate to high rainfall. It favours compact soils, and invades low maintenance turf areas.

• The most effective way to control this weed is to prevent its seed from spreading.
• Daily fluctuations in temperature, and exposure to light stimulate the germination of this weed grass.
• The aim should be to keep a full turf cover. This reduces temperatures fluctuations, and so prevents seed germination.
• Any bare or thin turf areas will enable Tussock Grass to germinate from seed.
• Hand remove small Parramatta Grass plants if there is not too much.
• Bag the seed head first to stop seed dispersal.
• Slashing or Whipper snipping before you use a herbicide also helps with control. 
• Rat’s Tail Grass favours compact soils, so soil aeration will help.
• Keep N up to your turf grass as it encourages a healthy turf cover.

The key is to try to manage Parramatta Grass before it goes to seeds.

• Dig it out, and try to minimize soil disturbance.
• Immediately place the entire plant in a sealed bag. Remove this off site asap.
• Regularly re-check the site for new Tussock Grass plants.

The following are non-selective. They have a long term residual and also stop re-growth of Parramatta Grass.

• Renegade. This stops Tussock Grass for up to 12 months. This reduces the need for repeat herbicide applications.
• Numchuk Quad. Numchuk Quad gives effective post and pre emergent Rat’s Tail control for up to 12 months.
• Cortex Duo. Gives a rapid knockdown, and gives residual control for up to 3 months. Cortex Duo is safe to use around trees.