Texas Invasives

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Federal Noxious Weed

TDA Noxious Weed

TPWD Prohibited Exotic Species

Invasive Plant Atlas of the US

NOTE:

means species is on that list.

Sorghum halepense

Johnson grass

Synonym(s): Holcus halepensis, Sorghum miliaceum
Family: Poaceae (Grass Family)
Duration and Habit: Perennial Grass/Grasslike

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Description

Perennial with vigorous rhizomes. Coarse grass with reddish to purplish-black panicles, to 2 m tall. Plants can rapidly develop colonies. Johnsongrass is considered one of the 10 most noxious weeds in the world. It is especially troublesome in cotton fields in California.

Native Lookalikes: Currently no information available here yet, or there are no native Texas species that could be confused with Johnson grass.

Ecological Threat: Johnsongrass grows rapidly, is highly competitive with crops, and can be difficult to control. Infestations in crops can reduce harvest yields significantly. Plants are highly variable and many regional biotypes exist. Healthy plants can provide good forage for livestock. However, foliage of johnsongrass and other sorghums can produce toxic amounts of hydrocyanic acid when exposed to frost, stressed by drought, or damaged by trampling or herbicides and may be poisonous to livestock when ingested.

Biology & Spread: Panicles retain seed or shed seed near the parent plant (shatter). Seed disperses to greater distances with wind, water, agricultural activities, and animals. Some seed survives ingestion by birds and mammals. Unlike commercial sorghums, glumes tightly enclose seeds and can protect seeds from decomposition in the soil for several years. Photosynthesis is by the C4 pathway.

History: Brought to South Carolina in the early 1800s as a forage crop. Continues to spread by seed dispersal in agricultural machinery.Introduced from the Mediterranean region.

U.S. Habitat: Disturbed sites, roadsides, fields, agronomic and vegetable crops. Grow best on fertile, well-drained soils in warm temperate to sub-tropical regions where some warm season moisture is available. Also orchards, vineyards, cotton fields, ditchbanks. Often grows in moist soils.

Distribution

U.S. Nativity: Introduced to U.S.

Native Origin: Africa, Asia

U.S. Present: AL, AR, AZ, CA, CO, CT, DE, FL, GA, HI, IA, ID, IL, IN, KS, KY, LA, MA, MD, MI, MO, MS, MT, NC, ND, NE, NH, NJ, NM, NV, NY, OH, OK, OR, PA, PR, RI, SC, SD, TN, TX, UT, VA, VT, WA, WI, WV, WY

Distribution in Texas: Located in nearly every state of the U.S., with the exception of some northern states. Located in all regions of Texas, including Harris, Brazoria, and Galveston counties of the lower Galveston Bay watershed.

Mapping

Invaders of Texas Map: Sorghum halepense
EDDMapS: Sorghum halepense
USDA Plants Texas County Map: Sorghum halepense

Invaders of Texas Observations

List All Observations of Sorghum halepense reported by Citizen Scientists

OBS# 817

OBS# 14737

OBS# 3312

Native Alternatives

Fall panicum [Panicum dichotomiflorum Michaux][PANDI] is a summer annual, to 1 m tall, that resembles johnsongrass. Nodes and internodes of fall panicum give the plant a zig-zag appearance. Unlike weedy sorghums, fall panicum has ligules that consist of a fringe of hairs and are not membranous at the base. Fall panicum seedlings are smaller than those of Sorghum and have short hairs on the lower side of the leaf blades.

Texas alternatives include Square-stem spikerush (Eleocharis quadrangulata)
Sugarcane plumegrass (Saccharum giganteum)
Powdery thalia (Thalia dealbata)

Management

Mechanical: Plants cannot tolerate repeated, close mowing. Repeated tilling every few weeks in summer or winter can help control infestations in agricultural fields. However, if you only till once a season the grass will grow back. Intensive tillage will suppress rhizome growth but moderate tillage will only break and spread rhizomes, allowing the plant to thrive. Crop rotations that include winter crops and crops planted in late summer also help control infestations. Spring burning encourages re-growth from rhizomes.
Chemical: Intensive glyphosate application has created resistance in 35 known weed species, including Johnsongrass. In Argentina, Johnsongrass has developed independent multiple types of resistance towards glyphosate requiring higher dosages for effective control.

USE PESTICIDES WISELY: ALWAYS READ THE ENTIRE PESTICIDE LABEL CAREFULLY, FOLLOW ALL MIXING AND APPLICATION INSTRUCTIONS AND WEAR ALL RECOMMENDED PERSONAL PROTECTIVE GEAR AND CLOTHING. CONTACT YOUR STATE DEPARTMENT OF AGRICULTURE FOR ANY ADDITIONAL PESTICIDE USE REQUIREMENTS, RESTRICTIONS OR RECOMMENDATIONS. MENTION OF PESTICIDE PRODUCTS ON THIS WEB SITE DOES NOT CONSTITUTE ENDORSEMENT OF ANY MATERIAL.

Text References

Fernandez L et al. 2013. Population genetics structure of glyphosate-resistant Johnsongrass (Sorghum halepense L. Pers) does not support a single origin of the resistance. Ecol Evol 3:3388-3400. https://doi.org/10.1002/ece3.671

Heap I, Duke S.O. 2018. Overview of glyphosate-resistant weeds worldwide. Pest Manag Sci 74:1040-1049. https://doi.org/10.1002/ps.4760

Howard, J.L. 2004. Sorghum halepense. In: Fire Effects Information System. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory.

Klein, P., Smith, C.M. Invasive Johnsongrass, a threat to native grasslands and agriculture. Biologia 76, 413-420 (2021). https://doi.org/10.2478/s11756-020-00625-5

Miller, J.H. 2003. Nonnative invasive plants of southern forests: a field guide for identification and control. Gen. Tech. Rep. SRS-62. Asheville, NC: U.S. Department of Agriculture, Forest Service, Southern Research Station. 93 pp (USDA SRS).

Warwick, S.I. and L.D. Black. 1983. The biology of Canadian weeds. 61. Sorghum halepense (L.) PERS. Canadian Journal of Plant Science 63:997-1014.

Online Resources

Encycloweedia, California Department of Food and Agriculture

The Quiet Invasion: A Guide to Invasive Plants of the Galveston Bay Area (www.galvbayinvasives.org). Lisa Gonzalez and Jeff DallaRosa. Houston Advanced Research Center, 2006.