Cogongrass Imperata cylindrica (L.) Beauv
June 25, 2009
Cogongrass and Brazilian satintail
Cogongrass [Imperata cylindrical (L.) Beauv.] and Brazilian satintail (I. brasiliensis Trin.) are aggressive, colony-forming dense erect perennial grasses 1 to 6 feet (30 to 180 cm) in height. Hybridization is probable and makes differentiation difficult. Both have tufts of long leaves, yellow-green blades (each with an off-center midvein and finely saw-toothed margins), and silver-plumed flowers and seeds in spring (and sporadically year-round). Seed are dispersed by wind and on contaminated clothing, equipment, and products like pinestraw mulch and fill materials. Seed viability appears at this time to be significantly less in northern Florida and southern Georgia and higher in southern Alabama and Mississippi.
Dense stands of dried plants remain standing during winter to present a severe fire hazard, while remaining green year round in central and southern Florida. These species burn hot even when green.
Infestations form dense rhizome mats make eradication difficult, because abundant shoot and rhizome buds usually sprout after treatment or lay dormant to sprout within months or years. Rhizomes are sharp-tipped and can pierce roots of other plants. Older infestations will be more difficult to control than new invasions, which occur as circular patches.
Both species are Federal and State Noxious Weeds, while red tipped cultivars are still sold and planted in many southern states. These cultivars, bred for cold hardiness, have viable pollen that might spread to the invasive cogongrass plants. Red cultivars can revert to the green aggressive type. Some southern states prohibit the sale of the red cultivars. For more details, visit www.cogongrass.org and other State cogongrass Web sites.Management Strategies:
- Do not plant the red tipped cultivars (Japanese bloodgrass and Red Barron). Remove prior plantings, and control sprouts and seedlings.
- Treat when new plants are young and located through frequent surveillance of lands in infested zones.
- Minimize disturbance within miles of where this plant occurs, and anticipate wider occupation when plants are present or adjacent before management disturbance.
- Repeated cultivation and planting of aggressive grasses or herbicide resistant crops can restore pastures and croplands.
- Burning and bush mowing treatments can remove standing plants for more efficient herbicide treatments. However, burning usually causes rapid infestation expansion and can kill native shrubs and trees that constrain spread.
- Seed production can be stopped by mowing, burning, or herbicide treatments in early stages or early flowering or even shortly before flowering. However, these treatments can cause flowering/seeding as well.
- Clean seed and rhizomes from equipment and personnel working in infestations before leaving the infested site.
- Forage quality is low, eaten only when shoots are young and tender by goats, sheep, mules, and some cattle. Recommended control procedures:
Thoroughly wet all leaves with one of the following herbicides in water with a surfactant when grass is at least 2 feet high and with multiple applications to regrowth at this same height: Chopper Gen 2* as a 4-percent solution (1 pint per 3-gallon mix), Arsenal AC* as a 2-percent solution (8 ounces per 3-gallon mix),; when safety to surrounding vegetation is desired, a glyphosate herbicide as a 2- to 5-percent solution (8 to 20 ounces per 3-gallon mix); or combination of the Chopper Gen 2* or Arsenal AC* and a glyphosate herbicide using lowered rates of all.
Repeat before flowering in spring to suppress seed production and again in successive years for eradication.* Nontarget plants may be killed or injured by root uptake.
Alabama Forestry Commission's Cogongrass Control Recommendations
Cogongrass management in longleaf pine document
Cogongrass Conference Proceedings