For help with controlling cogongrass on your property, learn more about the Cogongrass Control Program offered by the Mississippi Forestry Commission.
Cogongrass (Imperata cylindrica) is an invasive, non-native grass that occurs in the Southeast region of the United States. It is considered to be an invasive species in 73 countries and one of the “Top 10 Worst Weeds in the World.”
Cogongrass has several common names, including Japanese bloodgrass, Red Baron, or Speargrass.
Cogongrass produces upright, smooth stems 6–47 inches tall that form loose or densely compacted stands. Its dense stems and rooting system choke out other vegetation. Leaves of cogongrass display a midrib that is off-set (closer to one leaf margin than the other).
An unusual characteristic of cogongrass is its flowering pattern. It flowers immediately after the transition from dormancy to full greenup in the spring, typically from March to May, although warm winters may cause earlier greenup and flowering. Cogongrass can also flower following frost, fire, mowing, tillage, or other disturbances. Most native grasses that resemble cogongrass flower well after plants have turned green, rather than immediately after greenup. Flowers typically occur at the top of the stem and are easily identified by silvery or whitish, silky hairs attached to the seed that create the appearance of a feathery plume. Silver beardgrass [Bothriochloa saccharoides (Sw.) Rydb; Syn. Andropogon sacchariodes Sw.] can be confused with cogongrass. However, silver beardgrass is smaller, forms clumps rather than dense stands, and flowers in summer.
Each cogongrass plant can produce up to 3,000 seeds per season. Cross-pollination is necessary for seed production. Seedlings are frequently found in open sites that have been disturbed by clear-cutting, burning, tillage, excavation, grading, fire ant mounds, or other disturbances. Seedlings begin to produce rhizomes about 4 weeks after emergence.
Cogongrass is typically spread by wind, vehicles, equipment, animals, and contaminated soil.
In the Midsouth and other southern states, cogongrass usually occurs in non-cultivated sites, including pastures, orchards, fallow fields, forests, parks, natural areas, and highways, electrical utility, pipeline, and railroad rights-of-way. Cogongrass prefers sandy soils with low nutrient levels, although it will inhabit more fertile sites.
Cogongrass occurs as a weed in Alabama, Florida, Georgia, Louisiana, Mississippi, Oregon, South Carolina, Texas, and Virginia. Several thousand acres are infested with cogongrass in the southeastern United States; more than 1.2 billion acres are infested worldwide. Unfortunately, this weed continues to spread.
Currently, there is no single treatment that effectively eliminates cogongrass infestations. Roundup Ultra, Roundup Pro, or other brands of glyphosate (41% active ingredient formulations) at 5 quarts per acre or as a 1.5% solution will suppress cogongrass. Repeated applications each year for several years are needed for control. Applications of Arsenal, Imazapyr, Polaris, or Habitat (2 pounds imazapyr per gallon formulation) at 48 ounces per acre can be used in certain areas and provide excellent control up to 1 year after application.
Because Arsenal and Roundup are nonselective, applications may damage nearby desirable vegetation. Since Arsenal remains in the soil for long periods, its effectiveness on cogongrass and other plants may continue up to a year after application. Do not apply imazapyr herbicides within two times the dripline of any desirable vegetation.
Cogongrass will not persist in areas frequently tilled, so frequent tillage can control cogongrass in certain sites.
Mowing or burning will remove aboveground cogongrass vegetation, but these methods open the plant canopy for the emergence of seedlings and new stems from rhizomes.
Broadcasting or drilling Roundup Ready soybeans into cogongrass, followed by glyphosate applications, has been a very effective control method.
Source: Mississippi State University Extension Service
- Cogongrass Control Program
- Field Guide to the Identification of Cogongrass (PDF)
- Plant Profile – USDA Natural Resource Conservation Service Plants Database
- Five-year Cogongrass Supression Map in MS
- Video: Cogongrass, the Perfect Weed developed and produced by the Coastal Plains RC&D Center
- Video: Cogongrass on Fire, filmed on location in Alabama
Report a Sighting of Cogongrass
To report a sighting of this invasive grass, please call the Mississippi Department of Agriculture and Commerce – Bureau of Plant Industry at (662) 325-3390.