Macquarie Valley Weeds Committee & Lachlan Valley Weeds Advisory Committee


Coolatai Grass

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Botanical Name: Hyparrhenia hirta
Other Common Names:


Class Regions
Class 3Bland Shire Council,Cootamundra Shire Council,Dubbo Regional Council
Landholder Responsibilities: The plant must be fully and continuously suppressed and destroyed
Why Is It Bad?: Coolatai Grass is a serious weed of native environments, improved pastures and cropping situations. It has the ablility to spread quickly without the need for disturbance. It is of high importance that this weed is controlled at an early stage and eliminated before it becomes established. Coolatain Grass forms dense swards excluding all other vegetation. It is generally unpalatable, low in nutrient value, and infestations will reduce carrying capacity and production values. Coolatai Grass can be difficult to identify as it is similar to native grass species. It also poses a significant fire risk due to the large amounts of dead mass retained by the plant.


Habit: Grass
Leaves: Pale greyish-green sheathed leaves, greater than 40cm long, 2-3mm wide. Leaves are glaucous and glabrous. Ligules are 2-3mm long. Basal stems are bluish-purple. Seedlings emerge in late spring.
Flowers: Panicles are 15-40cm long and made up of sterile spikelets, sessile spikelets, and pedicellate spikelets. Racemes are paired, 1.5-5cm long with 5-8 awns per raceme. Flowering occurs in Autumn.
Fruit: Seeds are tine (2mm) and dispersed in an awned hairy husk.
Roots: Deep rooted, up to 3m. Coolatai Grass willl rapidly resprout from a basal crown after defoliation or dormancy.

Control Methods

Manual Removal: Small isolated infestations should be removed before they seed. When carrying out manual removal, ensure the basal crown is also removed.
Chemical Use: Mature plants are difficult to kill as the remaining old dry growth prevents good herbicide contact. Several applications may be required before the plant is killed.
Fire: Fire can be used to remove dead matter before applying herbicide to regrowth. Affects on surrounding vegetation needs to taken into account as Coolatai Grass is highly flammable.
Slashing & Cutting: If infestations occur at sites the require slashing (such as roadsides), ensure work is carried out before seeding and always clean machinery to prevent spread.
Biological Control: There are no biological control agents available for Coolatai Grass
Grazing: Grazing encourages growth of Coolatai Grass so to achieve an acceptable level of control, grazing pressure needs to be very high.
Cultivation & Scalping:
Monitoring: Successful treatment programs rely on ongoing monitoring of sites. Regrowth and new seedlings can easily become larger infestations if follow-up treatments are not part of the management program


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Image Credit: Stuart Moorby

Image Credit: Ashley Bullock

Image Credit: Glenn Neyland

Image Credit: Wendy Bushell

Image Credit: Wendy Bushell

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