June 16, 2008

Cogongrass Invades County: Experts Say Plant Could Turn State’s Forests into Savannahs

By Andy Johns, The Anniston Star, Ala.

Jun. 16--Alabama agencies are banding together to battle an invading Japanese grass that recently has crept into Calhoun County.

Experts say if the invasion isn't stopped, it could turn the state's forests into savannahs.

Cogongrass not only grows so thickly that other plants can't get roots into the soil, but its roots excrete chemicals that inhibit other plants. The underground stems, called rhizomes, are so sharp and grow so quickly they have been known to impale other plants, according to an expert.

"It's the whole arsenal," said Auburn University's Nancy Loewenstein, an extension specialist studying the weeds. "Anything bad that a plant does, cogongrass does it."

"It's beyond kudzu."

On May 13, 22 representatives from various state agencies signed a memorandum of understanding to form the Alabama Cogongrass Task Force. The group aims to at least slow the weed's invasion, which began in Mobile almost 100 years ago. Scientists believe seeds were brought over on a ship from Japan.

Dana McReynolds, a spokeswoman for the Alabama Forestry Commission, said the task force will use a federal invasive species grant to train personnel on the weed's characteristics as well as how to control and eradicate it.

The plant not only chokes out native plants, but patches of cogongrass are so thick that animals like gopher tortoises can't dig their burrows into the soil. Chemicals in the weed also cause it to burn quickly and at much higher temperatures than other grasses, increasing the damage and risk of forest fires.

"It pretty much takes over the entire site eventually," McReynolds said.

According to a map drawn by the University of Georgia's Center for Invasive Species and Ecosystem Health, the weed was found in Talladega County in 2004, in Cleburne County along Interstate 20 in 2007 and in St. Clair County in 2004.

Loewenstein said she received a sample from a patch of cogongrass in Piedmont this May, but did not know when the patch was first spotted.

Calhoun County Extension Agent David West said the spot was on private land and he believed it was first identified in 2006 or 2007.

Seeds and partial root systems from the cogongrass have been known to spread across the state through wind, transported fill dirt and on construction equipment, according to Loewenstein. She said she suspected patches in the Birmingham area may have sprung forth from seeds in the dirt of potted plants grown near the coast and transported north. In managed forests alone, cogongrass spreads over 2,000 acres per year.

The new task force hopes to turn the tide.

The spot in Cleburne County has been treated and other spots across the state have been contained, Loewenstein said.

McReynolds said the weeds are tough enough that burning them only allows them to grow back stronger. She said the most common method to eradicate cogongrass involves burning it first to destroy the dense surface thatch and then using herbicides to kill the roots.

Loewenstein said tilling up the patch six to eight inches deep several times over a season is another common method of eradication.

Anyone who sees cogongrass is urged to call the county extension office.


--In the roots, rhizome is sharp with a white papery cover. --Yellowish green leaves. --Feathery seedpods bloom in late spring or early summer. --Seeds disperse like dandelions. --After freeze it turns brown.

--Source: Alabama Forestry Commission

About Andy Johns Andy Johns is the mobile reporter for The Star. He is a graduate of Berry College in Rome, Ga.


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