Cogongrass along Mississippi's El Camino Real

On a sunny day in May, driving across Mississippi one is stuck by the sight of miles of silvery grass glistening and swaying in the wind and sun.  Depending on the time of day the reflection off the grass as it sways in the wind can be blinding.  So of course I had to stop, many times, to investigate this unusual grass that looked at first glance to be exotic (non-native).

A closer look reveals Cogongrass (Imperata cylindrica), an invasive, non-native grass that has been naturalized in the Southeast region of the United States. It is considered to be an invasive species in 73 countries and one of the top 10 worst weeds in the world, and it is everywhere in Mississippi.  But, there is no denying that it is enchanting when in full bloom.

Cogongrass (Imperata cylindrica) on US HWY 84 (El Camino Real) in Mississippi

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Cogongrass has several common names, including Japanese bloodgrass, Red Baron, or Speargrass.  It is not the same plant that is commonly smoked in the South as a rite of passage, that plant is commonly called Rabbit Tobacco (moe about that below).

Vegetative Growth

Cogongrass produces upright, smooth stems 6–47 inches tall that form loose or densely compacted stands. Its dense stems and rooting system choke out other vegetation. Leaves of cogongrass display a midrib that is off-set (closer to one leaf margin than the other).  The leaves of the grass are quite sharp if you catch them at the wrong angle.

Flowering

An unusual characteristic of cogongrass is its flowering pattern. It flowers immediately after the transition from dormancy to full greenup in the spring, typically from March to May, although warm winters may cause earlier greenup and flowering. Cogongrass can also flower following frost, fire, mowing, tillage, or other disturbances. Most native grasses that resemble cogongrass flower well after plants have turned green, rather than immediately after greenup. 

Flowers typically occur at the top of the stem and are easily identified by silvery or whitish, silky hairs attached to the seed that create the appearance of a feathery plume. Silver beardgrass [Bothriochloa saccharoides (Sw.) Rydb; Syn. Andropogon sacchariodes Sw.] can be confused with cogongrass. However, silver beardgrass is smaller, forms clumps rather than dense stands, and flowers in summer.

Each cogongrass plant can produce up to 3,000 seeds per season. Cross-pollination is necessary for seed production. Seedlings are frequently found in open sites that have been disturbed by clear-cutting, burning, tillage, excavation, grading, fire ant mounds, or other disturbances. Seedlings begin to produce rhizomes about 4 weeks after emergence.

Dispersal

Cogongrass is typically spread by wind, vehicles, equipment, animals, and contaminated soil.

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Habitat

In the Mississippi and other southern states, cogongrass usually occurs in non-cultivated sites, including pastures, orchards, fallow fields, forests, parks, natural areas, and highways, electrical utility, pipeline, and railroad rights-of-way. Cogongrass prefers sandy soils with low nutrient levels, although it will inhabit more fertile sites.

Distribution

Cogongrass occurs as a weed in Alabama, Florida, Georgia, Louisiana, Mississippi, Oregon, South Carolina, Texas, and Virginia. Several thousand acres are infested with cogongrass in the southeastern United States; more than 1.2 billion acres are infested worldwide. Unfortunately, this weed is very adaptable (rhizomes and copious seed production) so it is unlikely to be eradicated, anywhere, ever.

Control Methods

Chemical

I do not advocate using chemicals in the environment but a lot of people in the South use them regularly.  Chemicals are currently ineffectively against Cogongrass so using them only poisons the environment while temporarily slowing the growth of the grass.

Currently, there is no single treatment that effectively eliminates cogongrass infestations. Roundup Ultra, Roundup Pro, or other brands of glyphosate (41% active ingredient formulations) at 5 quarts per acre or as a 1.5% solution will suppress cogongrass. Repeated applications each year for several years are needed for control. Applications of Arsenal, Imazapyr, Polaris, or Habitat (2 pounds imazapyr per gallon formulation) at 48 ounces per acre can be used in certain areas and provide excellent control up to 1 year after application.

Because Arsenal and Roundup are nonselective, applications may damage nearby desirable vegetation. Since Arsenal remains in the soil for long periods, its effectiveness on cogongrass and other plants may continue up to a year after application. Do not apply imazapyr herbicides within two times the dripline of any desirable vegetation.

Mechanical

Cogongrass will not persist in areas frequently tilled, so frequent tillage can control cogongrass in certain sites.

Physical

Mowing or burning will remove above ground cogongrass vegetation, but these methods open the plant canopy for the emergence of seedlings and new stems from rhizomes.

Cultural

Broadcasting or drilling Roundup Ready soybeans into cogongrass, followed by glyphosate applications, has been shown to be an effective control method, but again you are dealing with a toxin that is nonselective, application may damage nearby desirable vegetation.

Cogon Gatherers

In the Philippines, Cogon grasses native range, there are so-called "cogon-gatherers," people who make a living by cutting and selling cogon grass.  This grass is used in its native range as a cheap material for roofing houses as well as other building s such as sheds for animals.  It is also used for sheds to dry tobacco (but it is not smoked).  Cogon-gathering is not a full-time occupation, although for some farmers it has turned into an important part of the agricultural calendar and is a major source of cash income.

The frequency and timing of burning in order to obtain the best quality of cogon grass as roofing material is important.  The cogon-gatherers burn towards the end of the dry season with the aim of rejuvenating and stimulating the growth of cogon, so that it will be of the same length during harvest time.  They also burn the fields after harvesting the cogon to get rid of all remnants and to destroy other weeds and shrub vegetation.  Read more about Cogon Grass in its native range in Indigenous Environmental Knowledge and its Transformations:  Critical Anthropological Perspectives (edited by Roy Ellen, Peter Parkes and Alan Bicker; 2005).

Rabbit Tobacco (Pseudognaphalium obtusifolium)

Rabbit Tobacco

Smoking rabbit tobacco is a rite of passage in the South.  Much like baptisms, bar mitzvahs, confirmations, school graduation ceremonies, weddings, retirement parties, and funerals are important in other parts of North America.

Rabbit tobacco is a different plant than Cogongrass but can look similar when in full bloom.   I can imagine that some have tried smoking cogon grass when rabbit tobacco was in short supply.  I know of Southerners also smoking cross-vine and other native plants that one wouldn't normally think of as smokable "weed."

Strongly aromatic Pseudognaphalium obtusifolium has no narcotic properties.  Usually smoked in a pipe one strips the crinkly gray leaves from the rabbit tobacco plans, packing them into the pipe and then passing around the lit bowl.  Read more about this rite of passage at the Tuscaloosa News in Ben Windham's "The Simple Pleasure of Rabbit Tobacco."

Pseudognaphalium obtusifolium
An Asteraceae family member
Yes, people still smoke it in the South