Six Echinochloa species, i.e. barnyard grass (Echinochloa crus-galli (L.) Beauv.), awnless barnyard grass (E. colona (L.) Link), hairy millet (E. oryzoides (Ard.) Fritsch), prickly barnyard grass (E. microstachya (Wieg.) Rydb), Japanese millet (E. esculenta (A Br.) H Scholz), and channel millet (E. inundata Michael et Vickery), were detected in surveys of Australian rice fields in south-eastern Australia. Differences were detected in the rate of germination of species and this may affect the efficacy of herbicide treatments where mixes of species occur.

Phenotypic variation within E. crus-galli, such as size of panicles, size of spikelets, and degree of awning, sometimes makes identification difficult and may have implications for seed growers.

No instances of herbicide resistance were found in any Echinochloa species despite its widespread occurrence in other countries.