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Scientific Name:

Common Name:

Sorghum halepense (L.) Pers.
Johnsongrass
Family: Poaceae

USDA Plant Code: SOHA

Habitat: Terrestrial; fields, rights-of-way, open forest

Growth Habit: Perennial Graminoid

Native Environment: Mediterranean Region

Introduction


Problems Caused
Johnsongrass [Sorghum halapense (L.) Pers.] is a perennial warm-season grass native to the Mediterranean. It was introduced as forage and escaped, especially along roadsides. It can cause cyanide poisoning in livestock, particularly in cattle, horses and sheep feeding on Johnsongrass following stress such as cutting or frost. Cyanide poisoning can also cause deformities in livestock offspring.

Regulations
Johnsongrass is Noxious in Arkansas, California, Delaware, Idaho, Illinois, Indiana, Kansas, Kentucky, Maryland, Missouri, Nevada, Pennsylvania, Utah, and West Virginia. It is a C List noxious weed in California and Colorado, a B designated weed in Oregon, and Class A noxious weed in Washington. It is prohibited in Ohio, quarantined in Oregon and Washington. Johnsongrass is regulated as a non-native plant species in South Dakota. It can be problematic in all MidSouth states, especially on roadsides.

Description



Johnsongrass Inflorescence Showing Panicle Size
Vegetative Growth
Johnsongrass is a rhizomatous perennial, forming dense stands. Stems can reach 6 feet tall. Stem nodes are appressed pubescent, but internodes are glabrous (smooth). Leaf blades are up to 25 inches long and just over an inch wide. They are pilose on the upper surface basally and sheath margins are glabrous or ciliate. Ligules are membranous, usually ciliate, about 0.1 inches long.

Flowering
Flowering occurs from May to October. The inflorescence is a panicle about 25 inches long and about 8 inches wide. The rachis and ascending branches are rough (scaberulous) and the raceme joints are pubescent. Spikelets are less than inch long with short pubescent pedicels. Glumes of fertile spikelet pubescent and those of staminate spikelet are glabrous or pubescent both less than inches long. Sterile and fertile lemmas are ciliate and slightly shorter. The awn on fertile lemmas may be present or absent, twisted geniculate and 0.25 to 0.75 inches long when present. The paleas are absent. The grain (caryopsis) is small, roughly 0.8 inches long, generally reddish and oblong to ellipsoid.


Johnsongrass Spikelets Showing Size, Shape, and Color
Dispersal
Johnsongrass can be spread both by rhizomes in soil and by seed in contaminated hay and equipment. Mowing, movement of contaminated soil, or other activities on roadsides or other areas can also spread johnsongrass.

Spread By
Johnsongrass is spread by seed and rhizomes.

Habitat


Johnsongrass is a problem in pastures, fields, prairies, roadsides and waste places. It can form dense stands, replacing the surrounding native vegetation. Although it can be utilized as a forage crop, caution should be taken because of potential cyanide poisoning. On roadsides, its height can obstruct visibility. It is tolerant of a wide range of terrestrial conditions, but generally does not tolerate deep shade.

Distribution


United States
Johnsongrass is widespread in the United States, possibly in all states except Maine and Minnesota. It has escaped in other parts of the world as well. It is easily spread both by rhizomes in soil and by seed in contaminated hay and equipment.

MidSouth
It is widespread in all MidSouth states, particularly in open areas along roadsides and in pastures.

IPAMS Surveys:

Control Methods


Postemergence Herbicides for Johnsongrass Control
Common Name Trade Name Method Rate per Acre
Asulam Asulox 128 oz
Bromacil Hyvar 7 to 15 lbs
Clethodim Select, Prism, etc. With crop oil concentrate 8 oz
Fluazifop Fusilade, etc. With crop oil concentrate 24 oz
Glufosinate Liberty, Finale With nonionic surfactant 128 oz
Glyphosate Roundup, etc. 128 oz
Imazamox Raptor, Beyond With nonionic surfactant 6 oz
Imazapic Plateau, Cadre, etc. With nonionic surfactant 6 oz
Imazapic + glyphosate Journey With nonionic surfactant 22 oz
Imazapyr Arsenal With nonionic surfactant 16 oz
Imazethapyr Pursuit With nonionic surfactant 6 oz
MSMA MSMA, etc. 2.5 to 6 pints
Nicosulfuron Accent With nonionic surfactant 0.67 oz
Primisulfuron Beacon With nonionic surfactant 0.76 oz
Prometon Bromacil 7.5 to 10 gal
Quizalofop Assure With crop oil concentrate 12 oz
Sethoxydim Poast, Vantage, etc. With crop oil concentrate 24 oz
Sulfometuron + Chlorsulfuron LandMark XP With nonionic surfactant 9 oz
Sulfosulfuron Maverick, Outrider With nonionic surfactant 1.3 oz
Biological
Aside from livestock grazing, no widespread use of biological controls is utilized in the United States. In pasture systems, three or more years of intensive grazing will significantly reduce johnsongrass populations. Frequent mowing is also effective for johnsongrass control. Likewise, flooding infested areas with 2 to 4 inches water for 3 to 6 weeks in early spring will kill most rhizomes, but will not damage viable seed in the soil.

Chemical
A number of herbicides are effective for johnsongrass management. These include asulam, bromacil, clethodim, fluazifop, glufosinate, glyphosate, imazamox, imazapic, imazapic plus glyphosate, imazapyr, imazethapyr, MSMA, nicosulfuron, primisulfuron, prometon, quizalofop, sethoxydim, sulfometuron plus chlorsulforon, and sulfosulfuron. Most require either crop oil or a nonionic surfactant.

Mechanical
No mechanical controls for johnsongrass are currently in widespread use. Mowing is a common practice, but does not generally eradicate johnsongrass. Since johnsongrass has long rhizomes, hand removal is difficult. However, hand removal for small patches in a landscape may be feasible.

Physical
Physical controls are generally not effective, although johnsongrass generally does not tolerate deep shade.

References


Knight, A.P., and R.G. Walter. 2001. A guide to plant poisoning of animals in North America. Teton NewMedia, Jackson, WY.

McWhorter, C. G. 1989. History, biology, and control of johnsongrass. Pp. 85-121 in Rev. of Weed Sci. Vol. 4, Weed Sci. Soc. Am.

USDA, NRCS. 2007. The PLANTS Database (http://plants.usda.gov, 6 August 2007). National Plant Data Center, Baton Rouge, LA 70874-4490 USA.

More Information


The Genus Sorghum belongs to the Grass (Poaceae or Gramineae) Family. Sorghum, with 24 species, is primarily native to the Old World, although species occur in Europe and Mexico. Sorghum halepense and S. vulgare Persoon (milo, grain sorghum) are the primary species escaped in the MidSouth. They are easily distinguished since S. vulgare is an annual, lacking rhizomes. Sorghum vulgare is not as invasive in the MidSouth and generally found where harvested grain was dropped from trucks or other farm equipment.

Contributing Authors


Dr. Victor Maddox, Geosystems Research Institute, Mississippi State University
Dr. Randy Westbrooks, USGS, Biological Resources Discipline, Whiteville, NC.


Contact Info


Dr. John D. Byrd, Jr.
Mississippi State University
Plant and Soil Sciences
Box 9555
Mississippi State, MS 39762-9555
Ph. (662)325-4537
jbyrd@PSS.MsState.Edu

Geosystems Research Institute
Contact: John D. Madsen, Ph.D.  •  WebMaster