Destructive cogongrass threatens crops, timber

Destructive cogongrass threatens crops, timber

2 November 2009

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USA — An invader is on the march in the Deep South, wreaking ecological havoc, cutting production in timber and agricultural crops and creating an extreme fire danger along the way.

Cogongrass is believed to have been introduced by accident through the Port of Mobile in 1911 or 1912, arriving as packing material in shipments from Asia. The non-native grass grows in thick circular patterns, choking out all native vegetation, said Bill Baisden, assistant state forester at the Alabama Forestry Commission.

And what happens in the fields and pastures has a huge impact in Alabama. Farming, which generates an annual economic impact of $43 billion, is the state’s No. 1 industry, according to Alabama Farmers Federation. The state has 48,000 farmers, and the agriculture industry creates 476,000 jobs in Alabama, or 21 percent of the state’s work force. The annual payroll of farm-related jobs is $9 billion, federation figures show.

The yield farmers see also has an impact on what you pay for groceries at the checkout counter.

Most residents are familiar with kudzu, the region’s more famous non-native weed that grows along roadsides and covers everything in its path with a mat of thick vines and leaves. Cogongrass offers a greater threat, economically and ecologically, Baisden said.

“Once it establishes itself, it just takes over,” he said. “It wrecks wildlife habitat; it’s very easily spread. It can grow to 5 to 6 feet tall.”

Baisden said cogongrass burns at a faster and hotter rate than native grasses, which can be a threat to firefighting crews.

“The fire will move so quickly you can’t get out if the way,” he said. “As people move out of cities and into the more rural areas, the spread of cogongrass poses an extreme fire danger for homes and other property.”

It’s not just homes that are in danger — people’s livelihoods are at stake. Timber and timber production is big business in the state. According to the Alabama Forestry Commission, Alabama has 22.7 million acres of forestland, or about 70 percent of the total land area of the state. It has the third most timberland in the contiguous states, behind Georgia and Oregon. In Alabama, 80 percent of the timberland is owned by non-industrial, private landowners, according to the commission.

The cogongrass is widespread throughout Alabama, Mississippi and Florida and is seen “sporadically” in Texas, Louisiana, Tennessee, Georgia and South Carolina, according to the Center for Invasive Species and Ecosystem Health at the University of Georgia. Anywhere from 1 million to 1.5 million acres are covered by the grass in the region, data from the center shows.

The grass is silver gray in color, with wispy seed heads mimicking Johnsongrass. The blades are sharp-edged, and the grass has a high silica content, which means livestock won’t feed on it. It has no natural controls in this country.

Alabama is using about $6 million in federal stimulus money in a two-year program to control and hopefully eradicate the weed. Alabama’s sister states also are trying new approaches to control cogongrass:

  • Florida: The state’s Department of Transportation is creating a database that uses GPS coordinates to locate cogongrass spots along highway rights of way. Grass cutting and earthmoving equipment easily spread cogongrass, said Dick Kane, communications director for the DOT. The grass has been reported throughout the Sunshine State, with the exception of the Keys and an area south of Miami.

    “Cogongrass spreads very quickly in disturbed areas, where there has been road construction and mowing,” Kane said. “We are trying to map the locations of cogongrass so our maintenance crews know where they are and can take precautions against spreading the grass. We have continuous training for our in-house and contract grass-cutting crews.

    “They need to know what cogongrass looks like. If they mow a spot and don’t clean the equipment thoroughly, all they are doing is spreading the grass.”

  • Mississippi: In Mississippi, several different state and federal agencies are working to control and eradicate cogongrass. Mississippi is working to join all the agencies under one cooperative effort to provide a better use of resources and more unified control, said Benny Graves, a cogongrass expert at the Bureau of Plant Industry in the state’s agriculture department.
  • Education is the key, Graves said.

    “People have to realize what a danger cogongrass is,” he said. “You can have a spot on your property and treat it. But if your neighbor across the fence has 40 acres of cogongrass and they don’t treat it, you’re wasting your time and money. Finding the spots and informing the property owners about them is a huge undertaking.

    “That’s why cooperation among all these different agencies is so important.”

  • South Carolina: There are cogongrass infestations reported in 10 of the state’s 46 counties, said Steve Compton, invasive species coordinator for Clemson University’s Department of Plant Industry. Clemson is spearheading the state’s fight to control the non-native grass. Cogongrass has been declared by agronomists as one of the 10 most dangerous weeds in the country, he said. South Carolina is using a task force of more than 200 volunteers to find the cogongrass spots, Compton said. The spots are then sprayed with herbicide.

    If not checked, the weed could spread through the upper Midwest and up the Eastern Seaboard, he said.

    “We hope we can eradicate the spots we have before it becomes too widespread,” Compton said. “Then the battle will be stopping reintroduction. All it takes is a small piece of the plant’s rhizomes stuck to a tractor or other machinery to spread cogongrass.”

  • Louisiana: The spread of cogongrass into Louisiana is following the rights of way of roads, railroads and pipelines, according to, a Web site maintained by Louisiana State University. The infestations are “restricted” in the state, but danger of the grass spreading is “high,” according to the site. The university is researching the use of selective chemicals that would kill cogongrass without causing mortality in native or beneficial plants, the site shows.

    Herbicides are the best way to control the spread of cogongrass, said Ernest G. Lovett of Larson and McGowin, a forest management and consulting firm out of Mobile that won the Alabama contract to fight the grass in early September. The company has been plotting spots since mid-September and has begun widespread spraying.

  • “It’s very important to develop a plan. We don’t want to do any harm to the native vegetation,” said Lovett, vice president and western division manager for the company. “We don’t have much time to do the actual spraying this year because we are near the end of the growing season.

    “We hope to have a plan in place for next year, so we can get more spraying done.”

    The strategy in Alabama is to eradicate the grass north of U.S. 80, which bisects the state. It sounds simple in theory, but reality rules in practice, said Stephen Pecot, a forester and environmental specialist with Larson and McGowin.

    “The state agencies had already mapped some spots, but as we scout, we are finding out how large the problem is,” he said, pointing to the situation in Greene County, a sparsely populated rural county in west Alabama. “The state had 12 spots in Greene County. Once we started scouting, we found 123 and are still counting.”

    Spots found in Alabama range from just a few square feet in size to more than 200 acres, Lovett said. The grass grows in pastures and woods. The control effort includes everything from portable backpack sprayers to more elaborate rigs on ATVs and large tractors.

    “If you get in an airplane, the cogongrass is very easy to spot,” said Tom Lang, county forester for Dallas County, about 50 miles west of Montgomery. “You fly over the west part of the state and some pastures look like they have the measles because cogongrass grows in circular patterns.”

    The grass can spread through the expansion of its thick root system. If you walk through cogongrass, you can feel the hard points of the roots at the surface of the ground, even through thick-soled boots. The ends of the root tips underground are needle sharp and their woody structure makes them very hard.

    Lang said he has seen photos of cogongrass roots that have forced their way through the roots of pine trees.

    Jamie Thomas found out firsthand about the danger of cogongrass and fire. Thomas, a forester, operates Industree Timber Inc. and manages a 700-acre tract of land for a hunting club in Dallas County.

    He set a controlled burn, a common timberland management practice, this past winter in a pine plantation on the property.

    “The fire was burning just fine until it hit a cogongrass spot I didn’t know was there,” he said. “The fire just exploded when it hit the cogongrass. It burned up most of the trees. Luckily, I was able to get a break around the fire, away from the cogongrass. It wasn’t a fun day in the woods.”

    For decades, cogongrass was centered in the coastal counties of Alabama, and Mississippi and Florida’s western Panhandle, said Baisden, Alabama’s assistant forester. That began to change after September 2004 when Hurricane Ivan, a Category 3 storm, came ashore at Gulf Shores. The strongest storm of the 2004 Atlantic season, Ivan caused widespread damage in Alabama, Mississippi, Florida’s Panhandle and southwest Georgia.

    “The cleanup and recovery effort after Ivan was massive,” Baisden said. “We had help and utility crews come in from states throughout the region. All that equipment moved earth and put in new utility poles for weeks, and sometimes months. Then they went home and carried cogongrass roots and seeds with them.

    “We have reached critical mass with the spread of cogongrass. It is set to explode in the next few years.”

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