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NWRC Coastal Prairie Research Program

COGONGRASS ALERT!

Cogongrass (Imperata cylindrica) is an agressive, perennial grass from Southeast Asia. Introduced into the United States on at least two separate occasions, this weed is currently invading Florida, Alabama, Mississippi, and Louisiana and has recently been discovered in East Texas. Cogongrass is considered one of the 10 worst weeds worldwide and is a pest in at least 73 countries. Although the transport of this plant into and throughout the United States is prohibited by federal law, cogongrass continues to spread throughout the southeast gulf coast threatening forests, rangelands, natural areas, roadsides, and residential areas.

WHY IS COGONGRASS A PROBLEM?

Cogongrass is an aggressive invader capable of displacing native vegetation,desirable pasture grasses, and tree seedlings in a wide range of soil types and conditions.cogongrass in a field

Cogongrass is unsuitable as a livestock forage because of poor nutritional value and low palatability.

Cogongrass is extremely flammable, capable of altering natural fire regimes; dense stands create a serious fire hazard.

Cogongrass spreads both by rhizomes and wind-dispersed seeds.

Cogongrass has no known pests or diseases to control its spread in the Southeast.

HOW DO I KNOW IT'S COGONGRASS?

Cogongrass is a yellowish-green, fibrous grass of variable size.

Long, erect leaves have a distinctive white, off-center midrib.

White rhizomes are scaly and tough, making removal of plants by hand difficult.

New shoots emerging from rhizomes are hard and sharply pointed; capable of piercing the skin.

Inflorescence is a solitary, terminal, tightly branched panicle that initially appears silvery, turning white and fluffy at maturity.

Flowering typically occurs from March through May.

Only cross-pollinating populations produce viable seed, although most populations will still produce the characteristic fluffy, plumed inflorescences.
cogongrass inflorescence

HOW IS COGONGRASS CONTROLLED?

An integrated approach that targets cogongrass rhizomes is required to provide long-lasting control. Repeated deep cultivation during the dry season can effectively dessiccate rhizomes, although tillage combined with a systemic herbicide (i.e., glyphosate) is more effective. Where cultivation is not possible or desirable, a combination of burning or mowing with repeated herbicide applications can control cogongrass. Burning or mowing alone stimulates cogongrass and so must be followed by herbicide. Burning or mowing is needed to remove dead biomass so the herbicide can be applied to actively growing leaves. Systemic herbicides are most effective when applied in the fall when cogongrass is storing carbohydrates in the rhizomes. Immediate revegetation of the area with more desirable species and retreatment of newly sprouting cogongrass with herbicide are necessary for effective control.

Controlling cogongrass requires persistence and diligence by the land manager but will be well worth the effort for protecting our natural resources from this very serious exotic invader.

The text for this page was prepared by Sharon King.

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Page Last Modified: Monday, 19-Aug-2013 16:49:33 EDT