At first glance Giant Parramatta Grass and Giant Rat's Tail Grass can look like just another clump of grass in the paddock - but they can quickly take over.
Invasive pasture weeds
Giant Parramatta Grass and Giant Rat’s Tail Grass are invasive pasture weeds that spread quickly, reduce grazing productivity and become difficult to manage once established.
Giant Parramatta Grass (Sporobolus fertilis) and Giant Rat’s Tail Grass (Sporobolus pyramidalis) are both listed as Asset Protection priority weeds under the North Coast Regional Strategic Weed Management Plan. This means the aim is to prevent further spread and reduce the density of existing infestations across the region.
The grasses quietly taking over paddocks
Both species are tall, tufted perennial grasses that form thick, expanding tussocks. They have tough, wiry leaves and livestock will avoid grazing them. Their narrow seed heads are held above the leaves. Giant Parramatta Grass generally holds its seeds close to the main stem, while Giant Rat’s Tail Grass has seeds on short branches extending away from the stem.
A clump of grass left untouched while stock graze around it may be worth a closer look.
Found wherever pasture is under pressure
Across the Port Macquarie Hastings region, these grasses may be found in grazing land, along roadsides and travelling stock routes, and in disturbed or overgrazed paddocks.
Areas with bare ground or weakened pasture are particularly vulnerable, as the weeds can establish where desirable pasture species have been reduced.
A serious threat to productive pasture
Giant Parramatta Grass and Giant Rat’s Tail Grass can reduce the carrying capacity of pasture and outcompete more desirable pasture species.
They also produce large quantities of seed, which can remain in the soil and create an ongoing management problem, particularly as they are spread through normal farm activity.
Once established, the grasses can gradually take over productive areas and become costly and time-consuming to control.
Sticky seeds that travel easily
The seeds become very sticky when wet and can be carried to new areas on machinery, vehicles, animals, clothing and footwear.
They may also spread through contaminated hay or feed, livestock movement, wind and flowing water.
Good farm hygiene is essential to prevent seeds from moving between paddocks and properties.
Stop small infestations becoming big problems
Regularly check paddocks, fence lines, tracks and areas where livestock gather. Early detection makes these weeds much easier to manage.
Landholders can also help reduce their spread by:
- cleaning machinery and equipment before moving between properties or paddocks
- avoiding hay or feed that may contain weed seeds
- maintaining strong, desirable pasture species
- avoiding overgrazing, which creates space for weeds to establish
- contacting Council early for help with identification and management advice.
More information is available through NSW WeedWise – Giant Parramatta Grass, NSW WeedWise Giant Rat’s Tail Grass and through the Weedy Sporobolus Grasses – Best Practice Manual. You can also contact contacting council’s Biosecurity officer to request advice or a copy of the manual.
Catching a small infestation early is far easier than dealing with a paddock full of these grasses later.
