Cogongrass (Imperata cylindrical) is an ever-present threat to not only our mitigation banks in Alabama, Florida and Mississippi, but most banks in the southeast. A native grass of Korea, Japan, China, India, and tropical eastern Africa, it is nonnative and invasive throughout the southeastern United States. Cogongrass grows in dense patches, up to six feet high. The leaves are often light, yellowish-green in color but can have a reddish cast in fall and winter. The silvery-white flowers are two to eight inches in length, generally blooming from late March to mid-June.
This exotic grass is thought to have arrived in the United States from Japan as a packing material by way of the Port of Mobile in 1912 and into Mississippi from the Philippines in 1921 as a possible forage grass. Whatever the means of arrival, it is here and spreading like wildfire, pun entirely intended.
Cogongrass presents specific challenges at our Chickasawhay Conservation Bank where we protect the federally-listed gopher tortoise and its required habitat. The gopher tortoise and Cogongrass thrive in the same upland, fire-maintained environment. In fact, Cogongrass is so well adapted to fire that response to fire is one of the distinguishing characteristics between its varieties.
Prescribed burning is an essential management tool at Chickasawhay Conservation Bank, with multiple burns taking place each year. Given the characteristic large and dense stands associated with Cogongrass, its fuel load is very high and can be catastrophic without controlling action. Additionally, mature plants lack moisture increasing the likelihood and length of fire. Aggressively controlling Cogongrass infestations is a high priority task in preventing wildfires and destruction of the critical habitat we have carefully restored on the bank. Cogongrass fire behavior is best described as explosive, as shown in this video.
Another serious problem Cogongrass presents is that it can also out-compete native vegetation that is a more appropriate food source for the gopher tortoise. The high silica content of Cogongrass leaves make them very unpalatable treats to almost all wildlife. Further, young shoots have sharp points that pose risks of mouth injury.
On Chickasawhay Conservation Bank, Westervelt Ecological Services manages Cogongrass infestations by flagging patches and applying prescribed herbicide treatments. It is not uncommon to apply treatments two, three or more times until the patch is successfully eradicated. Constant surveillance, treating new infestations, and ultimately, rehabilitation with native plantings are crucial in our management of this invasive grass.
We strongly encourage all land owners in the southeast to visit www.cogongrass.org to learn about efforts put forth by public and private agencies to control the spread of Cogongrass.