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Over the past decade, U.S. Forest Service researchers have been working with university cooperators to find some way to slow down or stop the relentless spread of cogongrass. This last fall, Auburn University researchers reported results that demonstrate, for the first time, that patches of cogongrass can be eliminated completely within three years — showing that eradication of the invasive plant is actually possible for many land managers.

Cogongrass is in a class of its own. Ranked the seventh worst weed in the world, it grows on every continent except Antarctica and is particularly destructive to the ecological structure of forests and natural areas, where the weed can literally take over understories.

Cogongrass currently occupies an estimated 66,000 forested acres in the U.S. South. It’s classified as a noxious weed in Alabama, Florida, Georgia, Mississippi, South Carolina, Texas, and Virginia, where it is widely believed to be impossible to eradicate. Estimated to spread 800 acres a year, cogongrass could infest 100,000 forested acres by 2060.

“Cogongrass grows mainly by extending rhizomes, which are like creeping rootstalks,” says Jim Miller, emeritus Forest Service Southern Research Station (SRS) researcher who helped with the study. “Cogongrass rhizomes are exceptionally aggressive, strong, and resistant to heat and water stress, making the plant a formidable and frustrating opponent.”

For the recently published study, researchers established a field study in two locations in southwestern Alabama where they applied herbicide treatments —  glyphosate, imazapyr, and a mixture of both —  in May, August, or October for three consecutive years.

From the USFS Southern Research Station: https://www.srs.fs.usda.gov/compass/2015/03/03/good-news-for-eradicating-cogongrass-in-the-south/