Parramatta Grass, along with most of the weedy Sporobolus grass family, has become a huge and increasing problem for landholders. This article discusses a couple of control methods and is not intended to be a definitive article on this grass family.
We own a 32 acre property in Peachester on the Sunshine Coast. We bought our property 12 years ago and started an extensive program of weed removal and replanting with endemic species. Our property could have been mistaken for a Camphor Laurel farm and their removal is ongoing, along with all the other usual suspects, mainly Small and Large-leaved Privet, Lantana, Yellowberry, Ochna, Castor Oil etc.
We also started improving the pastures. Two years later we noticed a one metre high tussocking grass with large black seed heads starting to appear in a few paddocks. It was not noticed until we completely rested one paddock, allowing this tussock grass to grow to its full height. Before spelling they were eaten off to low levels and were not obvious.
After investigation we confirmed that these large tussock grasses were Parramatta Grass (Sporobolus africanus), one of the weedy Sporobolus grasses (WSG) family. This WSG family is better known for the infamous Giant Rat’s Tail Grass (Sporobolus pyramidalis) and Giant Parramatta Grass (Sporobolus fertilis).
Once identified we started to notice Parramatta Grass in patches in all the cattle grazing paddocks with increasingproliferation over the next year. All weedy Sporobolus grasses are spread rapidly by stock, vehicle movement, wind and flood water. These grasses grow rapidly, are frost and drought resistant and carry approximately 80,000 seeds per plant. They have the ability to infest paddocks and ultimately overtake other more productive grasses and render properties virtually useless for stock. They are one of the biggest developing flora problems facing landholders in eastern Australia.
Thankfully there has been the development and availability of a WSG specific selective herbicide called fluproponate, which is marketed as Taskforce, Scuffle and other commercial names. Fluproponate will also work as a pre-emergent on the remaining soil seed bank as well as the parent plant. This chemical is successful but takes between 3 and 15 months to kill WSGs depending on weather conditions. It is washed into the soil by light rain and is subsequently taken up by the plants surface roots. It is most effective during summer months as the plant takes up the chemical more quickly. However, it may be washed out of the soil before becoming effective if application is followed by heavy rain, as is likely in the summer months.
Fluproponate is applied by spray and can be boom or spot sprayed. However it requires careful application. It must be applied at the precise rate as described by the manufacturer which requires calibration of boom sprays and this is seen as somewhat difficult to most landholders. If applied too heavily it may affect the other desirable grasses, too lightly and it is ineffective.
A new product called GP Pellets is now available. These pellets are a granular form
of fluproponate and have a fast release outer coating and a slower release inner. It can be applied by hand, mixed with fertilizer and spread accordingly but is very difficult to apply accurately with these methods. A hand-held spreader, such as the Scotts brand, is a much more accurate method of application but is not practical for larger areas.
The GP Pellet manufacturer offers a service using distribution by helicopter. This method applies the pellets very accurately using calibrated pods on the helicopter and GPS grid navigation. It applies the pellets very accurately in open fields and can apply them successfully through wooded areas and rough country which are usually not sprayed with boom sprays. This method may sound initially very expensive but when costed out the cost is almost the same as buying the pellets for the area. It has the advantage over other methods of very accurate distribution and huge time saving.
We treated our property using GP Pellets distributed by a helicopter, as well as our neighbours on either side (this is ideal), in March 2016. Shortly after treatment we had 5-10 mm showers every week or two and an unseasonally warm autumn, which resulted in a very active extended growing season. Three months after application there has been a very noticeable change in Parramatta Grass: A new control method weed profile Weedy Sporobolus grasses have the ability to seriously degrade properties and doing nothing is not an option. the Parramatta Grass infestation with most Parramatta Grass turning brown, dying or dead.
The base of dying or dead Parramatta Grass tussocks are now being overgrown with grasses and legumes, demonstrating that the fluproponate has only affected the Parramatta Grass. The manufacturer recommends a second application two years later to ensure near total eradication.
Weedy Sporobolus grasses have the ability to seriously degrade properties and doing nothing is not an option. They are considered Restricted Invasive Plants under the Queensland Biosecurity Act 2014 (formerly Class 2 Declared Pests), which means that the landholder must take reasonable and practical steps to keep their land free of this pest, and that plants must not be given away, sold or released into the environment.
Weedy Sporobolus grasses need to be addressed and GP Pellets along with their distribution by helicopter gives landholders a viable, practical and economical tool to control this major problem.
If you have WSGs on your property, we suggest that you refer to all resources available including local Land for Wildlife Officers, the Queensland State Government, Department of Agriculture and Fisheries and other landholders.
Article by Brian & Christine Stuart-Nairne
Land for Wildlife members
Peachester, Sunshine Coast