The grass spreads by seeds and by underground rhizomes. Its fluffy white seedheads can produce up to 3,000 seeds which, like dandelion seeds, can be blown up to 15 miles by winds, and are transported by animals when the seeds are caught in their fur.

Spreading also occurs from rhizomes and seeds on earthmoving and road maintenance equipment that has been used in infested areas. Land managers working on food plots and loggers often spread the grass in moving from one area to another, as do fire plows when wildfires occur.

“It takes four weeks from time a mature seed germinates until it starts producing rhizomes,” Browning notes. “With good soil and moisture conditions, it can spread up to 43 square feet from the time it germinates. Across an entire landscape, it doesn’t take long for an exponential spread.

The grass is also allelopathic — it produces chemicals that suppress growth of other plants.

“All this is a bomb waiting to happen,” Browning says.

Thinning of commercial pine plantations, which opens up the canopy and allows more sunlight, often opens the door to cogongrass invasion, which can quickly spread throughout the forest understory, hampering productivity of the trees and choking out desirable wildlife habitat.

Judd Brooke, a Hancock County, Miss., landowner, says the expense of fighting the grass has been “enormous — but we had to do it, because it was starting to smother out areas of the forest — there was no natural vegetation at all; it even choked out yaupons and wax myrtles. It was totally changing the characteristics of the forest. In areas where we were planting trees, no seedling would grow, the plant and root mass is so thick.”

J.B. Brown, a Stone County timber producer, says, “Until we thinned pines about five years ago, didn’t notice much cogongrass, but after thinning it was sprouting everywhere.

“It also has a negative impact on wildlife. Birds won’t consume the seeds. The grass is so thick, there’s no way turkey poults or quail chicks can navigate through it; they can’t nest in it or forage in it”

Randy Merritt, Mississippi Forestry Commission ranger, says cogongrass represents a major fire threat.

“Due to its high vegetative density and biomass, burning grass produces a very volatile fire that can reach temperatures of up to 850 degrees with flames five feet high, and spread very quickly. This high heat usually kills trees and surrounding vegetation, as well as endangering homes and farm buildings. If there’s any wind, we have trouble with it jumping firebreaks. Even with no wind, it’ll spread much faster than any other kind of fire, and it’s extremely hard to extinguish.”