Grass weeds

Guinea grass

Guinea grass (Panicum maximum) is a tall, rank grass from the small nation of Guinea in Africa. The main impacts of this grass are to out-compete native plants and to alter fire regimes. It is a particular problem close to rivers and on flood plains. However, this grass can be a valuable feed for stock and the idea of having it declared a weed is at odds with the efforts of many people to cultivate it for grazing purposes.

Giant rats tail grass

Giant rats tail grass (Sporobolus pyramidalis) is in the early stages of invading pastures in north east Queensland. It is an aggressive grass that can reduce pasture productivity and out compete most other desirable pasture grasses.

Commercial properties have shown cattle grazing GRT infested pastures can take up to 12 months longer to reach equivalent weight gains than those from non-infested pastures.

Giant rats tail grass is very similar to some native Sporobolus spp. and it can be difficult to identify.

The seeds of all species are indistinguishable in pasture seed samples using current seed sample identification techniques.

Grader grass

A heavy infestation of grader grass Photo: Greg Calvert

Grader grass

Grader grass (Themeda quadrivalvis ) is a relative of our native kangaroo grass but is much taller. It was accidentally introduced as a contaminant in pasture grass seed and is declared a noxious weed in the Northern Territory but not in Queensland.

It forms tall thickets covering large tracts of land, smothering native plants and reducing diversity. It also invades crops such as sugar cane and lucerne and thereby causes financial losses as well as environmental. The fuel loads produced by grader grass causes fires of an intensity that many native plants have not had to deal with before and therefore, thinning of native woodlands occurs with each passing fire.


Buffel is not a declared weed but there is concern its spread into non-target areas can displace native pastures Photo: Greg Calvert

Buffel grass

Grader grass was an accidental introduction, unlike buffel grass (Cenchrus ciliaris). Buffel is one of the most widely sown pasture grasses in western Queensland and dominates over much of these areas. It is resilient under grazing and tolerant to drought - features that make it an excellent pasture species.

However its spread into non-target habitats has been identified as a potential problem. From tests conducted by CSIRO, it is thought that while native grasslands were in good condition they excluded buffel. During the recent drought years in north east Queensland (1993), however, buffel started to invade native paddocks. TS–CRC and CSIRO are currently sponsoring research into the spread and impact of buffel grass.