Quick Facts

  • Perennial, rhizomatous grass that grows 2-4 feet in height with bright yellowy-green foliage
  • Leaves are about an inch wide, with a prominent white midrib and sharp end point
  • Leaf margins are finely toothed and embedded with silica crystals
  • Upper surface of leaf blade is hairy near base
  • Undersurface is usually hairless
  • Flowers arranged in silvery, cylindrical, branching structure (panicle), about 3-11 inches long and 1 ½ inches wide
  • Has been found in Alabama, Florida, Georgia, Louisiana, Mississippi, South Carolina, Texas, and Virginia

Species Facts:

Cogongrass, imperata cylindrical, is a hardy species, tolerant of shade, high salinity and drought. It can be found in virtually any ecosystem, especially those experiencing disturbance. Cogongrass has been found growing on sand dunes in the southeast, along roadsides, mining sites, borrow pits, forests, open fields, and up to the edge of standing water. Following initial invasion, cogongrass often forms dense, field-like monocultures. A pest in 73 countries, and considered to be one of the "Top 10 Worst Weeds in the World", cogongrass affects pine productivity and survival, wildlife habitat, recreation, native plants, fire behavior, site management costs and more.

Cogongrass was introduced to the United States both accidentally and intentionally. It was first introduced to the U.S. at Mobile, Alabama, via shipping crates that contained cogongrass as a packing material. It was also brought in and distributed by the USDA for use as a forage grass and for soil erosion control. Cogongrass is a Federal Noxious Weed valued for its attractive foliage and hardness and is sold by nurseries as the ornamental cultivar Red Baron bloodgrass, Japanese bloodgrass, japgrass or speargrass, valued for its attractive foliage and hardiness. However, Cogongrass can lose its red color and become a problem weed.

Cogongrass reproduces both vegetatively and from seed. A single plant can produce several thousand very small seeds that may be carried great distances by the wind. Vegetative spread of Cogongrass is aided by its tough and massive rhizomes that may remain dormant for extended periods of time before sprouting. Rhizomes of Cogongrass may be transported to new sites in contaminated fill dirt or by equipment used in infested areas.

Prevention: One should avoid soil disturbance, timber harvest, fire, etc. unless as a part of a specific treatment regime. A person should always clean equipment after operating in infested areas.

Mechanical/Cultural Prevention: One should mow or prescribe a burn prior to herbicide application to remove built-up thatch and promote active growth herbicide uptake. Someone should not mow when seedheads are present. Also, one should not burn without a follow-up herbicide treatment.

Chemical Prevention: A person should allow 12 inches of re-sprout before applying herbicide. Most managers recommend a foliar application of 2% glyphosate (eg. Roundup/Accord), or 1-1.5% imazapyr (eg. Arsenal/Chopper) (be aware of soil activity), or a tank mix of the two herbicides. One should apply the herbicide by spraying all foliage just until wet to the point of run-off. Links to Identification and Control Guides.

Timing: If someone can only do one treatment a year, he/she should apply the treatment in the fall before the first frost. Otherwise, one should re-treat regularly whenever adequate foliar re-sprout has occurred in infested sites.

The early summer (May) flowering time is a unique characteristic for identification of Cogongrass and should assist in detection. One should look at non-cultivated disturbed sites, such as pastures, orchards, fallow fields, forest, natural areas, and highway, electrical, utility, pipeline, and railroad rights of way.

Image of Cogongrass (Photo from: www.bugwood.org Credit to: James H. Miller)