Johnson-Grass

Invasive Alien Plant Species of Virginia Johnson Grass (Sorghum halepense (L.) Persoon)

Description Threats Johnson grass forms dense clumps Johnson grass is regarded as a ma- and grows to eight feet tall. Before jor agricultural weed, especially in the flowers appear, its long, smooth corn fields, where it forms tall, leaves with a white midvein are dense stands. The dead stems and characteristic. The stems may be leaves of this perennial herb cover pink to rusty red near the base. Its the ground all winter. It aggressively flowering inflorescence is large and crowds out native species, most of- loosely branched. It produces red- ten along riverbanks. Along forest dish-brown seeds which are ap- edges, it can slow the natural suc- proximately 1/8th of an inch long. cession of fields to woodlands. Johnson grass is similar in appear- ance to eastern grama grass Control (Tripsacum dactyloides), big When cut, the underground stems bluestem (Andropogon gerardii) (rhizomes) of Johnson grass and indian grass (Sorghastrum resprout, forming new plants. The nutans). Consult an agricultural ex- plant is resistant to many common tension agent or a natural resource herbicides as well. These factors specialist if your identification of the make Johnson grass a pernicious plant is in doubt. weed. Small stands may be controlled by handpulling the plants Habitat when the soil is moist. Severe in- Johnson grass occurs in cultivated festations can be controlled by re- and abandoned fields, forest edges, peated mowing to kill seedlings. streambanks, roadsides, vacant lots Mature plants, however, require re- or any disturbed ground. peated winter tilling to expose and Distribution kill root material. Spring burning This plant is found in virtually ev- may encourage regrowth therefore ery county and city in Virginia. It it is not recommended as a control was introduced to the United States method for this species. from its native range around the Control of Johnson grass with Mediterranean Sea. In fact, Johnson herbicide requires several applica- grass has spread to most warm-tem- tions with proper timing to insure perate regions of the world. It is effectiveness. Glyphosate herbicides listed by the Virginia Department of are recommended because they are Agriculture and Consumer Services biodegradable. However, gly- Johnson Grass (Sorghum halepense as a noxious weed. phosate is a nonselective, systemic (L.) Persoon)

For more information, contact the Department of Conservation and Recreation or the Virginia Native Plant Society. Virginia Native Plant Society Blandy Experimental Farm 400 Blandy Farm Lane, Unit 2 Boyce, VA 22620 (540) 837-1600 217 Governor Street, Richmond, VA 23219 (804) 786-7951; http://www.state.va.us/~dcr/vaher.html http://www.vnps.org Jim Gilmore, Governor • John Paul Woodley, Jr., Secretary of Natural Resources • David G. Brickley, Director, Department of Conservation and Recreation Invasive Alien Plant Species of Virginia Johnson Grass (Sorghum halepense (L.) Persoon) herbicide which will affect all green cialist or an agricultural extension Harvill, A., et. al. 1992. Atlas of the Virginia vegetation. To be safe and effective, agent before attempting this control Flora. Virginia Botanical Association, herbicide use requires careful measure. Burkesville. knowledge of the chemicals, appro- References Hutchinson, M. 1992. Vegetation priate concentrations, and the effec- Management Guide: Johnson Grass. Illinois Fernald, M. L. 1950. Gray’s Manual of Nature Preserves Commission. tive method and timing of applica- Botany, Eighth edition. American Book tion. Consult a natural resource spe- Company, New York. Illustration by Donna Smith.

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