Invader of the Roadside and Landscape

Eddie Powell
Horticulture Agent
Walton County
732 North 9th Street
Defuniak Springs, Fl   32433

You have probably seen it along our Florida roadsides, but you may not have recognized just how dangerous it is.  “It” is cogongrass, considered one of the ten most noxious plants worldwide.  And it is now a major pest in the Southeast.   So much so, that states and the federal government are all concerned about its spread.

Cogongrass that has been bushhogged on the roadside. Photo Credits: Eddie Powell

The grass entered our country through the port of Mobile, Alabama, where it had been used as packing material in shipping crates.  It was also once approved by the USDA for use as forage and for erosion control.  But cogon had something else in mind.  It is an aggressive invader which disrupts ecosystems, reduces wildlife habitat, decreases seeding of native plants, and alters fire regimes.  The government is so concerned about this weed that it asks you to contact your state department of agriculture if you have it on your land.

Cogongrass leaf blade Photo Credits: Eddie Powell

At first glance, you might consider cogon to be an attractive grass.  It sports a silver white plume, cylindrical in shape, which appears in late March to mid-June.  The grass can be six feet long, although it is more commonly 3-4 feet long, and one inch wide.  It’s a light yellowish green color and somewhat hairy.

Tightly packed huge rhizomes aid in its spread.  It tends to infest in circular formations.  It can reproduce from seed; in fact one plant can launch thousands of wind-borne seeds.  Seeds stuck on equipment can also spread the weed.

It takes a concerted commitment to control cogongrass.  It’s recommended to mow the area in late spring.  Then wait six to eight weeks and disc deeply.  Next step is to apply herbicide. Call your local extension office for information on new herbicides for control.  Replant the area with a native grass to keep the cogon from reappearing. 

It is also possible to use controlled fire measures to beat back the invader.  The problem with the fire method is that cogongrass has a substance that burns exceptionally hot and makes fires harder to manage.  The rhizomes can lay dormant for a long time just waiting to re-infest an area. Don't let this invader on your landscape or land!