Grains Research and Development

Windmill grass (Chloris truncata)

Windmill grass in fallow

Photo: A. Storrie

Windmill grass (Chloris truncata) is an erect, hairless, warm season biennial or short-lived perennial to 0.5 m high, usually forming a dense low crown, sometimes with short, branched stolons. The leaf blade is 2 to 5 mm wide with a blunt (obtuse) and boat-shaped tip and has a ligule consisting of short hairs.

Flower spikes are usually six to nine in number, resembling fingers radiating horizontally and 4 to 20 cm long. Spikelets are arranged alternately in two rows on the underside of the spikes. Florets are black when mature and the seed is ovoid.

Factors that make Windmill grass a major weed:

  • Windmill grass is difficult to control in no-till fallows and can reduce the yield of winter crops
  • Prolific seeder
  • A host to cereal diseases
  • Seed-heads blow in the wind, enhancing its spread

Further detail about this weed including integrated weed management tactics that could be considered when developing a management plan can be found in the section on problem weeds in the Integrated Weed Management Manual.

Further information

Ecology and biology of common weeds are outlined in section 6 of the Integrated Weed Management Manual.  

Update papers

Status of key summer fallow weeds in the Riverina an update (2016)

Biology and management of summer weeds (2015)

Weeds and resistance considerations for awnless barnyard grass chloris and fleabane (2014)

Windmill grass (Chloris truncata) the current state of play (2011)

GRDC Video links

Groundcover TV episode on Windmill Grass (2011)

Other information

Ecology and management of windmill grass, Queensland Alliance for Agriculture and Food Innovation, Qld Department of Agriculture and Fisheries and the NSW Department of Primary Industries (2016)

Control of windmill grass over the summer fallow increases wheat yield (2009), 17th Australasian Weeds Conference (2010) (CAWS)