Weeds of tropical Australia.
In a review of grassy weeds of crops and pastures in tropical Australia it is stated that most of these weeds are exotic in origin. The occurrence of the following weeds and possible control measures are described. Rottboellia cochinchinensis and Mimosa invisa are important in sugarcane, Eleusine indica and Setaria sphacelata in tea, Echinochloa colonum, Cyperus iria and a variety of red rice in rice, Echinochloa spp. and Xanthium spp. in cotton, Pennisetum pedicellatum in sorghum, and Sorghum halepense, S. verticilliflorum and Cenchrus echinatus in maize, sorghum, groundnuts and many horticultural crops. The most important pasture weeds are Imperata cylindrica on infertile burned land, Themeda quadrivalvis on over-grazed land and roadsides, and Hyparrhenia rufa and Pennisetum polystachion both currently spreading along roadsides. The threat to tropical Australia from 8 further grass species found in countries to the north of Australia is discussed.