War on Weedy Sporobolus Grasses (WSG)

1. Giant Parramatta Grass (Sporobolus fertilis).).

2.Parramatta Grass (Sporobolus africanus).

We have a problem with both of these weeds in our pasture.

Below is a summary of weed facts for those from the Weeds Australia website.

• Giant Parramatta Grass (Sporobolus fertilis) is long-lived grass usually growing 70–160 cm tall, but occasionally reaching up to 2 m in height. It forms large tussocks up to 40 cm across.
• It is native to the Indian sub-continent (India and Sri Lanka), eastern and south-eastern Asia (China, Japan, Korea, Taiwan, Myanmar, Indonesia, Malaysia, the Philippines and Papua New Guinea) and some islands in the western Pacific.
• It is a vigorous, persistent and invasive grass that is well adapted to a wide range of climatic conditions.
• GPG is a particularly serious problem in pastures in the wetter areas on the north coast of New South Wales, but has the potential to invade much of eastern Australia.
• It is of low palatability and significantly reduces the productivity and carrying capacity of pastures.
• GPG also invades native grasslands, open woodlands, conservation reserves and wetlands. It replaces native plants in these habitats and can eventually change the community structure of, and threaten the biodiversity of, native grasslands and rangelands
• The use of a pressurised wick wiper to selectively apply herbicide to Giant Parramatta Grass is probably the most useful tool in managing this species.

• Originally from Southern Africa, Parramatta Grass (Sporobolus africanus) is a tough perennial tussock grass that grows to a height of 50–70 cm and reproduces from seed.
• Occurs as a weed in moist areas such as degraded pasture, roadsides and waste areas.
• Occurs in all states and territories of Australia especially in coastal areas.
• Its presence can seriously reduce pasture production and is so tough it can loosen teeth of grazing animals.
• It may be controlled by cultivation and the use of herbicides.

I have been spot spraying with glyphosate for the Parramatta Grass for years but the infestation has grown to a point where I have to wave the white flag.

The giant variety is a new addition probably seeded from my neighbour who does nothing much to control it. 

Seed is spread by wind, birds and animals, in our case the cows and kangaroos.

So far the spot spraying is working but am sure like its cousin, the spread will eventually become uncontrollable.

There is no official biologcal control for these weeds.
However, on the north coast of New South Wales there appeared to be a native soil fungus, Nigrospora oryzae, that did. 

This fungus is a saprophyte ie. a decomposer. It breaks down dead organic matter into fungal biomass.

Trials by agriculture authorities failed to give this treatment the official go ahead but people on the land have utilised it with some success, initially by transplanting infected plants among the WSG infestations.

A company, Beechwood Biological Solutions, has managed to concentrate the fungus on a specially prepared substrate which they market as a soil ameliorant.

It is called SOIL Trooper.

SOIL Trooper logo

We decided to give this a trial as a biological control of WSGs based on the anecdotal and practical documented experience of others.

The substrate comes in an air sealed plastic envelope. It looks like a mass of wet dead grass.

It is washed in fresh chemical free water and then mechanically mixed (drill driven paint stirrer) to release the spores and hyphae of the fungus.

It is then strained through a 450u mesh filter to get rid of the solid matter and diluted for spraying at a rate of 200L/ha.

Application is best done during damp weather on the top of slopes, on tracks and around animal feeding areas.

The fungus then spreads slowly down hill or via animal and vehicle movement.

Granted it will be a slow process of treatment but less onerous than continuous chemical spraying.

Results will be published here in what I imagine is the far distant future.