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Agricultural Review

Workshop raises awareness of invasive weed

The discovery of the federally regulated noxious weed cogongrass in North Carolina prompted a recent workshop in Scotland County to raise awareness about this non-native, invasive plant.

This is only the fourth time the plant has been found in North Carolina, and regulators with the N.C. Department of Agriculture and Consumer Services’ Plant Industry Division are now working to eradicate the established stand near Marston to prevent it from spreading.

About 100 people attended the workshop, including staff from the N.C. Forest Service, the N.C. Wildlife Resources Commission, N.C. Division of Parks and Recreation and others interested in knowing what the plant looks like and what they need to do if they think they spot it.

That’s exactly the type of audience Bridget Lassiter, weed specialist and workshop organizer, was hoping to draw. “By sharing information and showing people what they are looking for, it gives us more eyes on the ground looking for this and other invasive pests,” she said.

In fact, the Scotland County site was discovered when a Forest Service employee noticed a tall, spring-green patch of grass growing amid a stand of loblolly pines on the side of the road in December. Because he thought that was unusual, he reported it to his supervisor and also District 3 Service Forester Tom White who had experience with cogongrass in Stanly County. White called in Lassiter.

While the patch looks similar to decorative and generally harmless ornamental grasses, Lassiter said cogongrass is anything but harmless. With a high silica content, the plant burns around 800 degrees, which is much hotter than a typical grass fire would burn. With controlled burns designed to stimulate tree growth, that hot of a fire would more likely damage trees and put property at risk, Lassiter said.

The plant’s invasiveness also is problematic.

“Alabama spent $6 million one summer and didn’t make a dent in it. There’s a million acres of it in Florida,” said Steve Compton, the imported fire ant coordinator in South Carolina who is also responsible for tracking and eliminating cogongrass in that state. “It’s eating up heritage preserves in Alabama and taking over bogs and areas with pitcher plants.”

In addition, the dense root system of the plant chokes out other desirable plants that provide habitat and food for wildlife. In contrast, animals do not eat cogongrass because of its sharp blade-like foliage.

Eradication is difficult

Compton and Lassiter agree that public awareness is the greatest tool in eradicating this plant.

“I have never found cogongrass myself, and I have been working with it for 12 years, ” Compton said at the workshop. “All sites that I’ve identified and treated were from people who recognized it and called me about it.”

Finding stands of the plant as quickly as possible is important in trying to eliminate it, as the battle becomes more difficult after the plant has spread for some time.

“I met a colleague who had been trying to eliminate it from a pasture for 11 years,” he said. “You can’t walk away from it. The key is monitoring it for four to five years after it’s gone. In some Third World countries, people have moved because they couldn’t grow crops because of the cogongrass.”

Lassiter said that is why there is a sense of urgency about treating sites each time a new one is discovered. “Newer sites are easier to treat than established sites,” she said.

“We’re not giving up. Georgia is not giving up and South Carolina is not giving up,” Lassiter said. “There are over 1,000 sites being monitored in Georgia and they are committed to eradicating it. There are 10 sites in South Carolina and they are committed to eradicating it, too.”

Lassiter said the site has now been treated with a herbicide to kill the plants. A controlled burn will take place in the fall to remove biomass on the ground, making it easier to spot new growth next year. Extensive monitoring and more treatments will follow in the coming years.

Tips for identifying cogongrass

For many people, distinguishing between ornamental grasses can be confusing.

Lassiter said the presence of yellowish, light green leaves even in the winter can be a telltale sign. The plant has blades that are up to 6 feet long and about 1 inch wide. The leaves have a whitish, prominent midrib that can be off center.

Cogongrass is not a bunch grass. It grows in singular stems, with each leaf going almost all the way to the ground, she said. When you pull a leaf back from the stem, it is very hairy where the leaf attaches. Lassiter said cogongrass is a lot hairier than other common weedy grasses that would be growing in the wild, which helps distinguish it from others.

The plant blooms from late March to mid-June, with a silvery-white seed head that is 2 to 8 inches long. It is compact and cylindrical in shape with light, fluffy, dandelion-like seeds.

It is a rhizome, meaning the plant spreads underground through its root system. The rhizome can become a dense mat under the soil surface, which can be difficult to dig a shovel into. It also has lots of segments along the roots, including sharp, pointy pieces that can puncture skin.

Digging up the plant as a way to eradicate is not recommended, as this will likely only spread it to other locations.

Additionally, the plant tends to spread out in a circular fashion, eventually choking out other plants and trees as it spreads. At the Scotland County site, there are no trees or other plants growing in the center and denser portion of the cogongrass stand.

For more information on cogongrass, go to www.invasivespeciesinfo.gov/plants/cogongrass.shtml. If you think you may have found a cogongrass site, contact Lassiter at 919-707-3749.

 

NCDA&CS Public Affairs Division, Brian Long, Director
Mailing Address:1001 Mail Service Center, Raleigh NC 27699-1001
Physical Address: 2 West Edenton Street, Raleigh NC 27601
Phone: (919) 707-3001; FAX: (919) 733-5047


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