If it makes a list as the top 10 worst of anything, chances are it can't be good. And if that identifiable nuisance is rapidly becoming a common plant in Mississippi, that makes the situation even more ominous.
Cogongrass has been in the United States for decades, but only in the last few years was it labeled a noxious weed in Mississippi. The aggressive, resilient and prolific grassy weed is considered by international botanists as the seventh worst weed in the world. It is known to infect 35 crops in 73 countries and can be found on more than 1.2 billion acres worldwide.
In the Mid-South and Southeast, cogongrass has crept into forage and pasture operations, along highway rights of way and into pine and hardwood plantations where the weed vigorously competes for the water and nutrients needed by forage grasses, trees and wildlife.
Randy Browning, a wildlife biologist with the U.S. Wildlife Service and the Mississippi Fish and Wildlife Foundation, says now that landowners, state agencies and, in many cases, the general public have learned to recognize the plant and its dangers to agriculture and wildlife, that Mississippi is beginning to make progress on suppression of the weed in some areas and possibly even eradication in some of the lesser-infected areas.
Browning spoke recently to an overflow crowd at a Cogongrass Seminar in Jackson, Miss., sponsored by the Mississippi Department of Agriculture and Commerce's Bureau of Plant Industry.
“Cogongrass will displace entire native communities,” says Browning. “Cogongrass competes intensely for available light and nutrients. Landowners have found instances where the roots of the cogongrass literally grew through the roots of the trees. This stuff is tough.”
Cogongrass is also a physical barrier to seedling establishment of native plants, says Browning. It keeps other plants from germination. An example is yaupon, which is being choked out by cogongrass.”
Cogongrass might possibly offer a short-term forage value, but mature leaves are unpalatable to livestock because of high silica content and because the young shoots have sharp points.
“Even goats won't eat cogongrass,” says Browning.
Cogongrass can have a negative impact on numerous wildlife species, because the insects and other food sources they rely on simply cannot survive in cogongrass, and the grass is so thick it's unsuitable for nesting.
“It's virtually a biological dessert. Nothing feeds on it. It's too thick for nesting. It's too thick to even get through,” says Browning.
Other concerns are the impact cogongrass infestations are having on real estate values, primarily in southern Mississippi
Cogongrass has several common names, including japgrass, Japanese bloodgrass, Red Baron and speargrass. Its scientific name is Imperata cylindrical. The grass was first introduced into Mobile, Ala., in the early 1900s as a forage grass and as an erosion control plant. Neither proved a good decision.
According to Browning, cogongrass isn't particular about where it grows and responds to sandy light soil or heavy clay soil in sun or shade.
“It tolerates extreme drought and extreme water, even water logging. It thrives in disturbed areas such as cutover sites and roadsides or in undistributed areas,” says Browning.
“It is the first blooming grass we have in the spring, and the seed are easily dispersed by the wind for miles. It has high seed germination rates and high seed viability, as high as 90 percent or better seed germination in some trials.”
Browning and John D. Byrd, weed scientist with the Mississippi State University Extension Service, say one of the reproductive strengths of cogongrass is it produces rhizomes that give rise to nodes every 0.5 to 1.5 inches. Each node can produce up to 350 shoots.
“It can invade 43 square feet in 11 weeks,” says Browning.
“It will bloom unlike any other warm-season grass you are familiar with,” says Byrd. “It blooms right out of dormancy, and then it greens and grows the rest of the summer.”
Cogongrass does not bloom in the fall, rather it gets a reddish coloration, which is very distinctive and makes cogongrass easy to identify.
“There are a number of other grasses you could easily confuse with cogongrass, such as broomsedge or bahiagrass, but seedheads of bahiagrass are quite different from cogongrass,” says Byrd. “Don't be fooled by silver beardgrass, which is very common around Starkville and central Mississippi. Silver beardgrass doesn't bloom until midsummer and then blooms all the way through fall. Remember, cogongrass blooms right out of dormancy,” says Byrd.
Flowers typically occur at the top of the stem and are easily identified by silvery or whitish silky hairs attached to the seed, which create the appearance of a feathery plume.
According to numerous informational publications now being widely dispensed through a multi-agency effort to rapidly accelerate identification, growth patterns and control methods, cogongrass produces numerous upright smooth stems 6 to 47 inches tall, which form loose or densely compacted stands. Because of the dense stems and rooting system, cogongrass usually chokes out existing vegetation.
One unique characteristic for identification is that the midrib of the leaf is off-set (closer to one leaf margin than the other).
In Mississippi and other Southern states, cogongrass usually occurs in non-cultivated sites, including pastures, orchards, fallow fields, forests, parks, natural areas, and highway, electrical utility, pipeline and railroad rights of way.
Cogongrass can grow to heights ranging from 6 inches to 4 feet, but the average height is about 3 feet.
Cogongrass is confirmed in 50 of Mississippi's 82 counties. In the southernmost of those counties, botanists and biologists speaking at the seminar shared agreement that suppression of the weed is a more attainable goal for that area than eradication. However, in northern Mississippi, where the grass is still only in leading spots, the specialists are hopeful chemical and production control can eradicate the weed from some areas.
During the past few years, numerous control studies by private and public agencies led to some successful recommendations for control. However, the studies also identified some control efforts best avoided by landowners.
“Due to its high vegetative density and biomass, burning cogongrass can reach temperatures of 842 F at heights ranging from 0 to 5 feet, which usually ends up killing trees and all other surrounding vegetation,” says Browning.
While natural dispersal of the seed via the wind is a common method of spreading the plant, man is also contributing to the rapid expansion. Flowers and rhizomes on highway construction equipment, moving of contaminated dirt, disking of fire lanes, landscapes and failing to clean contaminated equipment before moving it to new areas all help spread the weed.
Cogongrass can be spread through contaminated nursery stock, turf and hay, which easily documents the presence of the plant along highway rights of way.
“One of the things we need is a standard operating procedure to be developed for the decontamination of equipment,” says Byrd. “That needs to be brought into our strategies for control.
“Sanitation is critical. If you are mowing in the spring when it is blooming, you are going to have debris on the tractor, around the radiator, and on the mowing equipment that needs to be cleaned off before you leave that field and go to another area,” warns Byrd.
“We are trying to get a handle on how far these seeds can move by wind dispersal. It could be as far as 50 miles, which is a lot further than we want to realize. I really think it would be best to not even mow this weed during blooming.”
Other control strategies have been developed, including multiple chemical applications with compounds such as Roundup and Arsenal. Other suppression efforts include regular mowing and repeated deep-disking following mowing.
“Currently there is no single treatment that effectively eliminates cogongrass infestations,” says Byrd. However, the weed will not persist in areas that are frequently cultivated, which is Byrd's explanation for why row crop producers aren't yet battling the grass.
“However, as more growers rely on no-till operations, I am concerned we could allow cogongrass into some of these fields,” says Byrd.
“We know the problem's in south Mississippi, but we can find it now in Lee County and Carroll County just by driving along the highway. Our plans are to develop new survey techniques using global positioning systems and spatial technology to see it in other places as well.”
Byrd says cogongrass begins blooming in south Mississippi about April 1 and moves northward. Blooming begins in the Starkville area by April 15.
The best of the alarming news from the cogongrass seminar is that some cost-share assistance money is available to help landowners control cogongrass.
“We have come so far in two years,” says Benny Graves, plant pest program director with BPI. “Cogongrass is a real problem and even more of a problem if it's on your land.
Graves says with some federal funds, the BPI was able to provide 218 landowners with chemicals to treat about 2,000 acres of cogongrass-infested land in 2003.
“That sounds like a small acreage, but it is a start,” he says. “We have come a long way in a year. We hope to continue that program. We have 200 applications in a waiting mode to be sure we get the money. More information on the cost share program is available on the BPI Web site at www.mdac.state.ms.us/Library/BBC/PlantIndustry or by contacting a local Farm Service Agency office.
Eva Ann Dorris is a free lance writer from Pontotoc, Miss. e-mail: [email protected].