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Perennial Sorghum Species


Johnsongrass: Sorghum halepense - Poaceae Family

Sorghum-almum (Columbus grass): Sorghum almum parodi - Poaceae Family

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Sorghum grasses include many different variants and can hybridize easily with each other. Johnsongrass and Columbus grass are two species with particularly invasive habits.

Identification of Columbus grass

  • Flowers: Loose, branching clusters growing 6-24 inches long with lax, spreading branches. Panicles droop as seeds grow larger.
  • Seeds:  Reddish-brown to black, oval, 0.25-0.4 inches long.
  • Leaves: Leaves are 2.5-4 cm. wide and waxy. Stems are 1 inch thick and can reach up to 14 feet tall.
  • Flowering Time: June to September.
  • Life cycle:  Perennial that spreads via thick short rhizomes. 

Impacts of Columbus grass

  • Native to South America, Columbus grass is a hybrid between Johnsongrass and Grain sorghum.
  • Columbus grass was intentionally grown as a forage crop in Australia, but escaped cultivation and now can be found infesting ditches, canals, fields, pastures, and roadsides.
  • Columbus grass quickly establishes in disturbed soils, sending out underground runners that sprout many stems and quickly form dense stands. 

Identification of Johnsongrass

  • Flowers:  An open panicle with thousands of spikelets.
  • Seeds:  A single plant may produce more than 80,000 seeds in a single growing season, and 275 feet of rhizomes.
  • Leaves:  It has wide leaves with a thickened whitish midrib.  The leaf ligule is jagged and membranous.
  • Flowering Time:  June to September.
  • Life cycle:  Johnsongrass is a hardy 2-8 foot tall perennial that spreads through seed and creeping lateral root systems.   In addition to a typical fibrous root system, Johnsongrass produces thick cream-colored rhizomes, covered with orange scales. 

Impacts of Johnsongrass

  • Originally introduced as a forage grass from the Mediterranean.  Unfortunately, under frost or moisture stress, it becomes toxic to livestock.
  • Johnsongrass is primarily a weed in row crops and can reduce crop yields in corn, sorghum, soybean, and cotton.



Most effective control methods for Columbus grass

  • Small infestations of Columbus grass can by removed manually by digging up individual plants. Care must be made to remove as much of the plant as possible, as stems will regenerate from rhizomes left in the ground. Repeated tilling can also be effective.
  • Larger infestations require a combination of control methods. Cultivate in the summer before seeds heads form, then apply herbicide on regrowth.
  • In pastures, spot spraying and maintaining a strong and competitive pasture will help prevent infestation.
  • Chemical control can be effective against Columbus grass when plants are actively growing. Herbicide treatment is particularly successful on seedlings and young plants before they flower.  

Most effective control methods for Johnsongrass

  • Preventing Johnsongrass from becoming established in new areas is the best available control method, because the weed spreads in so many ways. Because Johnsongrass is a perennial weed, single cultural control measures or herbicide applications rarely provide adequate control.
  • To reduce Johnsongrass infestations with herbicides, it will be necessary to use an integrated approach consisting of soil-applied herbicides, post emergence herbicides, crop rotation and tillage.


Large Images

Agrobase Australia

Columbus grass: going to seed


D. Walters and C. Southwick, Table Grape Weed Disseminule ID, USDA APHIS PPQ,

Columbus grass: seeds


John D. Draeger, University of Wisconsin-Stevens Point

Columbus grass: infestation 


John D. Draeger, University of Wisconsin-Stevens Point

Columbus grass: stem, foliage, and flowers


John D. Draeger, University of Wisconsin-Stevens Point

Columbus grass: seeds



Charles T. Bryson, USDA Agricultural Research Service,




Chris Evans, University of Illinois,

Johnsongrass: stem and foliage


Ohio State Weed Lab , The Ohio State University,

Johnsongrass: flowers


Steve Dewey, Utah State University,

Johnsongrass: fruit


Steve Dewey, Utah State University,

Johnsongrass: roots


Howard F. Schwartz, Colorado State University,

Johnsongrass: seedlings


  • Johnsongrass Fact Sheet

  • Sorghum Almum (Columbus Grass) Fact Sheet

  • References

    Global Invasive Species Database. (2010, October 4). Sorghum halepense. Retrieved from

    Heuze, V., Tran, G., & Baumont, R. (2015). Columbus grass (Sorghum x almum). Retrieved from

    Howard, J. (2004). Sorghum halepense. Fire Effects Information System. Retrieved from

    Invasive Species Compendium. (2018, July 14). Sorghum halepense (Johnson grass). Retrieved from

    Michigan State University. Columbus grass (Sorghum almum). Retrieved from

    Newman, D. (2015, February 17). Sorghum halepense. Retrieved from

    Osmond, R. (2014) Columbus grass (Sorghum x almum). Retrieved from

    Warnert, J. (2016, March 4). Invasive superweed Johnsongrass is the target of a new nationwide research effort. Retrieved from

    United States Department of Agriculture. (2015, August 12). Weed Risk Assessment for Sorghum halepense (L.) Pers. (Poaceae) – Johnsongrass [PDF file]. Retrieved from View PDF