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“Cogongrass is so aggressive, if left unchecked it can replace an entire ecosystem,” says Jim Hancock, invasive plant control program coordinator for the Mississippi Forestry Commission at Brookhaven. It has been called “the weed from hell” and “the mother of all invasive species.”
Came into U.S. in 1912
It was introduced into the U.S. at Grand Bay, Ala., in 1912 as packing material for a shipment of satsuma orange rootstock from Japan. It was later used in Mississippi and Florida in forage test trials and for erosion control.
Various cultivars (Japanese bloodgrass and Red Baron grass among them) have been used by landscapers and new varieties continue to be introduced, much to the dismay of invasive plant managers and researchers.
No northern boundary for overwintering has been established, but researchers say most of the eastern U.S. and Pacific Northwest may also be at risk.
In a video presentation, “Cogongrass — The Perfect Weed,”
produced for the Mississippi Coastal Plains Resource Conservation & Development Council, Inc., which serves six coastal counties — George, Hancock, Harrison, Jackson, Pearl River, and Stone — Randy Browning, U.S. Fish and Wildlife Service/Mississippi Fish and Wildlife Foundation, says cogongrass “has no known value and no known enemies.
“Researchers found out pretty quickly it had no value as a forage crop because of its high silicon content.”
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.