Toxic Parts:
cyanogenic glycosides
Flower Color:
  • flower color
haybales, meadows, woodlands, ornamental

Time of Greatest Risk


Geographical Distribution

Johnsongrass distribution - United States

Related Species


Sorghum halepense

8/ 10
Johnson grass (Sorghum halepense) is a coarse, extremely competitive, perennial, rhizomatous grass that grows in clumps or nearly solid stands. It is thought to be native to the Mediterranean region but has been introduced to temperate regions worldwide. Johnsongrass can often cross with other Sorghum species, which results in plants which are difficult to identify accurately. It has adapted to a wide variety of habitats including open forests, old fields, ditches and stream banks.

Johnsongrass Toxins

Johnsongrass has the capability of producing high levels of cyanogenic glycosides and nitrates, which can be lethal to horses if ingested.

What Johnsongrass Looks Like

  • Roots: Fibrous with thick rhizomes.
  • Stem:Green to maroon-colored sheath, especially near the base of the plant; Round to somewhat flattened.
  • Leaves: Rolled in the shoot, without auricles and with a prominent white midvein; toothed, membranous ligules; leaf blades usually have no hairs on both surfaces, but may be present at the base of the leaf blade.
  • Seedhead: Large, purplish tinted, open panicle that develop during the summer months. Seeds are dark red to black at maturity, oval-shaped, 3 - 5 mm in length.
  • Look alikes: Barnyardgrass (Echinochloa crus-galli)) and/or Fall panicum (Panicum dichotomiflorum) prior to seedhead formation.


  • Staggering
  • Difficulty Breathing
  • Anxiousness
  • Recumbency
  • Convulsions
  • Bright Red Blood Color
  • Chocolate Brown Blood Color
  • Death


CHEMICAL CONTROL: Application of glyphosate at 2 qt/A. It is essential to thoroughly cover all foliage, and higher rates of glyphosate may be required to control other weeds or sod that may be present.

MANUAL CONTROL: Mowing every three weeks, and allowing the grass to regrow between mowings. The first mowing should take place before the grass produces seed.