Plant invaders pose problems in state

Linda Benedict, Van Osdell, Mary Ann  |  1/11/2011 1:02:05 AM

Chinese privet is not the only plant that has invaded the Louisiana landscape and created problems for farmers, forest owners and homeowners.

Hallie Dozier, an assistant professor in the School of Renewable Natural Resources, says the introduction of foreign plants often causes problems because these plants don’t have natural enemies to control their spread.

One of the top invasive plants in Louisiana is the Chinese tallow tree, often called popcorn or chicken tree, she said.
 
"Characteristics that make a plant a good ornamental can help make a plant a good invader," Dozier said. "It flowers and fruits and produces lots of seeds."

Flowering plants are attractive to pollinators, and plants that produce fruit attract "dispersers" – primarily birds, she says. "So people who like bees and birds in their yards like these plants."

In addition to flowering profusely and producing fruits and seeds, other characteristics of invasive plants include the ability to thrive under a wide variety of growing conditions and tolerate significant above-ground damage.

Left unchecked, Chinese tallow trees began growing in wet prairie soils in southeast Louisiana, where they transformed the ecosystem from a grassland environment to a woodland en vironment. "That changed all the rules for all the animals that used that system," Dozier said.

Dozier said insect and disease resistance are common among invasive species. These traits not only make them hardy in the wild but also allow them to thrive in cultivated locations.

Kudzu was planted extensively for erosion control in Georgia and Alabama woodlands and is now in northeast Louisiana, Tunica Hills and south Louisiana, Dozier said. "It is tough to manage, growing as much as a foot a day, and takes a minimum of six to seven years of repeated mechanical and herbicide treatment before a site can successfully be re-planted and restored."

Cogongrass is a new forest problem in Louisiana, primarily in the Florida parishes, where conditions are conducive for its growth, Dozier said. It is moving west from Florida and Alabama, where it was introduced as forage for grazing cattle.

"Unfortunately, it’s only good for grazing when it’s small," Dozier said. "When it grows taller than a few inches, it becomes rough and unpalatable. If managed while in small clumps, there might be some success in preventing its spread and the problems they have faced in neighboring states and elsewhere in the South."

Mary Ann Van Osdell

(This article was published in the fall 2010 issue of Louisiana Agriculture.)

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