Coolatai grass

Coolatai grass has been found in the ACT. It was first detected locally around 2018.

About the pest

Coolatai grass (Hyparrhenia hirta) is an invasive, drought and fire tolerant tussock-forming perennial (meaning living for multiple years) grass. It dominates pastures over a range of soil types and conditions.

It has become a major invasive species in northern NSW and is spreading southwards. Infestations have been discovered to the north and south of the ACT.

Why it is a problem

Coolatai grass is one of the few perennial grasses capable of invading undisturbed natural ecosystems. It is a major threat to natural biodiversity in nature reserves and National Parks.

It is also a threat to grazing productivity due to low levels of protein and digestibility.

What to look for

• Coolatai grass produces short rhizomes that form dense grass tussocks and grow to 1.5 m.
• It has greyish-green leaves that turn orangey-red in winter, particularly after frost. The leaves are harsh to touch. Leaf sheaths are usually hairless and keeled. The leaf blade is flat and 2–3 mm wide with the ligule 2–3 mm long and minutely toothed.
• The seedhead is made up of pairs of small spike-like parts, each carrying 5–8 long bristle-like pieces. These paired spikes can be up to 35 mm long and grow out from leaf-like structures below them that are 3–8 cm long.

How it spreads

Coolatai grass spreads exclusively through seeds, which feature hairy, awned husks that easily attach to animals, clothing and vehicles. Because of this, it primarily spreads along roadsides and drainage lines, and through agricultural equipment. It is highly self-fertile, allowing a single plant to quickly generate large, invasive populations.

Report sightings