Invader from Asia

Cogongrass, called one of the world’s worst weeds and known for its nail-sharp roots and ultra-flammable oils, is creeping its way into North Georgia.

Department of Transportation officials noticed a patch of cogongrass along Interstate 75 in Catoosa County earlier this summer, causing concern across the region.

“It could potentially be another kudzu,” said Ray Dorsey, the state’s agronomist.

Labeled the seventh worst weed in the world in the 1977 book “The World’s Worst Weeds,” cogongrass is spread throughout Mississippi, Alabama and Florida, where seeds are believed to have been imported from Asia in packing material and accidentally set loose at U.S. ports.

Cogongrass’ discovery in Catoosa County is one of the northernmost patches on record, according to data from the Center for Invasive Species and Ecosystem Health at the University of Georgia.

Cogongrass has been found in only one Tennessee county — Henderson County in West Tennessee, according to the data.

“You can see how close it came to Tennessee,” Mr. Dorsey said. “We definitely don’t want it to move in up there.”

The patch along I-75 is fairly typical, experts say. The weed often is spread by roots and seeds carried on mowing or construction equipment moved around the state. While the patch was only 40 feet by 40 feet, Catoosa County forester Josh Burnette said transportation department crews have taken special care to kill it and still have two more treatments scheduled to ensure that it’s dead.

The problem with the weed, he explained, is it crowds out native plants and has no known value for wildlife in native ecosystems.

“You can kill kudzu by getting a goat to eat it, but even a goat or a cow, you can’t get them to touch cogongrass,” Mr. Burnette said.

Additionally, he said, the weeds catch fire quickly and the oils in them burn extremely hot, presenting a hazard to firefighters and nearby structures while increasing the spread of forest fires.

James Johnson, forest health coordinator for the Georgia Forestry Commission, went further, saying that cogongrass, if unchecked, could turn a diverse forest into a “monoculture,” choking out everything except itself.

“It will literally take over just about any ecosystem,” Mr. Johnson said.

For a more direct impact on humans, the weed also can be painful for unsuspecting passers-by, experts say.

Mr. Johnson said walking barefoot on a patch with its sharp root would feel like “walking on a bed of nails,” and Mr. Dorsey said the serrated blades of the weed also pose a hazard.

“If you weren’t wearing long pants, it would probably cut your skin,” he said.

Both men agree that educating the public is the key to combating the spread of the weed.

Mr. Johnson asked the public to be on the lookout for the feathery, white, cottonlike seed heads from March through June and report any sightings to local extension offices. Forestry crews will treat patches on private land with the landowner’s permission, he said.

In Georgia, cogongrass is not yet as entrenched as other invasive plants such as kudzu or the exotic hedge privet, according to Mr. Johnson. He said scientists only can hope to manage those species, while cogongrass still could be eradicated.

“Cogongrass is one (battle) we think we can win,” Mr. Johnson said.