Is Cogongrass Taking Over Your Lawn?

Weeds are plants capable of causing public health crises, economic losses, and ecological harm. They thrive and spread in various conditions, damaging natural resources, major agricultural processes, and wildlife habitats.

Cogongrass, also known as Japanese blood grass, is a weed that does all of the above. This pesky non-native plant is causing serious issues in the lower region of the United States. If you don’t know much (or anything at all) about cogongrass, buckle in. We’ll discuss this wicked weed and how to know if it’s infesting your lawn.

What Is Cogongrass?

Cogongrass (Imperata cylindrica) is an exotic perennial grass species known for its aggressive growth habit and drought tolerance. Since it arrived from Southeast Asia to America in 1911, cogongrass has earned its spot on the Federal noxious weeds list. It disrupts thousands of acres in the Southeastern United States, mainly in Florida, Georgia, Alabama, Louisiana, Mississippi, South Carolina, Virginia, Texas, and Oregon.

This invasive plant doesn’t just torment gardens and crops in North America; it’s currently recognized as the seventh worst weed in the world. According to the Mississippi Forest Health Program, cogongrass infests over 1.2 billion acres of land worldwide and continues to overtake more.

Infestations often occur along roadsides, rights-of-way, and undisturbed pastures where the soil is drier and less fertile. However, the settings safe from this persistent spreader are few to none. Cogongrass is capable of destroying residential lawns and gardens, too.


Why Is Cogongrass So Bad?

Cogongrass has rhizomatic root systems that spread up to 48 inches below the soil. Along with their deep rooting capabilities, the rhizomes produce needle-like points that slice through other plants’ tender roots. Worst yet, each cogongrass rhizome produces numerous more plants, leading to near-uncontrollable proliferation.

This rapid spreading habit allows the grass to outcompete native species for natural resources and outlive them during unfavorable climate conditions. As the weed spreads, it stamps out existing grasses and native perennials that are critical to the ecosystem. The United States Department of Agriculture (USDA) says that cogongrass infestations steal precious food resources from many threatened species, including the Henslow’s sparrow, bobwhite quail, gopher tortoise, and eastern indigo snake. Even grazers like cattle and goats won’t feast on the grass because it’s too sharp and silica-rich.

The plant’s presence in hotter, drier states also makes it a huge burn risk. Cogongrass is severely flammable and produces dry, scorching flames capable of burning through even fire-tolerant trees like mature longleaf pines.

Signs of a Cogongrass Infestation

By now, you can probably tell that cogongrass is one problematic plant. You don’t want it in your state, much less your lawn and garden. The first step to stopping a full-blown infestation before it occurs is knowing how to identify the weed in a natural setting. The University of Georgia Warnell School of Forestry provides these common cogongrass identifiers:

Plant Part Description
Flowers and Seed Heads
  • 2 to 8-inch long seed pods
  • Fluffy dandelion-like heads with a silvery-white color
  • Typically blooms from March through June
  • 6-foot-long grass blades with prominent white midrib
  • Yellowish-green color throughout spring and summer
  • May turn reddish brown in the fall and winter
  • Leaves are erect but may droop over as they grow
  • Leaves sprout directly out of the ground and are usually surrounded by thick thatch buildup
  • Densely matted rhizomatous roots
  • White color covered by brown, flaky scales
  • Sharply pointed at the ends

Cogongrass is fast spreading, which means you’ll rarely see one plant by itself. If you notice a weed with the above characteristics, look around for more. Patches of cogongrass are often dense and circular, with plants growing up to 6 feet tall. If the climate is chilly, the patch may be more brown instead of green.


Cogongrass Control Methods

Controlling cogongrass is no easy feat. This weed is incredibly persistent, constantly growing new shoots. Even if you successfully kill a cogongrass plant aboveground, it likely has a hardworking, reproductive rhizome system belowground. This endless proliferation makes total eradication seem near impossible.

Luckily, land managers and forestry officials are serious about controlling cogongrass. This push for weed control has led to a few solid options for eliminating unfriendly flora. We’ll go over some effective chemical and physical cogongrass control methods next.

Chemical Control of Cogongrass

Few herbicides are capable of completely controlling cogongrass. However, chemical formulations containing glyphosate and imazapyr are the most effective.

Glyphosate and imazapyr are systemic herbicides that prevent plants from producing vital proteins. They block plants’ enzyme pathways, leading to withering and eventual death. Imazapyr is used in commercial pesticides like Arsenal, Polaris, Habitat, and Chopper. Glyphosate is the active ingredient in popular herbicide treatments like Roundup, Rodeo, and Aquamaster.

Imazapyr and glyphosate herbicides are non-selective and will kill any plant. Consider this factor before applying these chemicals to your lawn.

The Center for Invasive Species and Ecosystem Health lists the following tips for controlling cogongrass in residential settings:

  • Perform herbicide application in the early fall, preferably August through October.
  • Produce a tank mix of about 5 fluid ounces* of herbicide per every gallon of water.
  • Be careful to keep the solution and spray drift away from desirable plants.
  • Treat regrowths the following spring and fall to ensure rhizome elimination.
  • Suppress new infestations by replating the area with cover crops, perennial grasses, or shrubs.

*Depending on the size of the infestation, you may need a far lower percentage of herbicide in your solution. Always read the product’s label and instructions before use.

Physical Control of Cogongrass

Physical control methods like hand-pulling and weed eating won’t work for cogongrass. The weed’s roots are simply too expansive and aggressive. Additionally, the rhizomes are sharp, making hand pulling a dangerous endeavor.

If you have a large yard or pasture overtaken by cogongrass, you can try to manage the infestation with tillage. Tillage is the process of working the ground with a large machine called a till. Though primarily used to prepare fields for crop planting, tillage can also be an effective way to break up extensive root systems.

Control cogongrass by tilling the infested area throughout its growing season. Start in the early spring and repeat every six to eight weeks, turning over the soil from at least 6 inches down. For smaller infestations, mowing can be a temporary solution. Cut down the cogongrass patches frequently at your mower’s lowest height setting.

Regardless of the equipment you use for physical eradication, clean it thoroughly after every use. Cogongrass seeds and rhizome segments spread easily via lawn care equipment.

Final Thoughts

Identifying cogongrass in your landscape is the first step in controlling it. Without identification tools and knowledge about the plant’s harmfulness, you may have an infestation on your hands without even realizing it. But equipped with the knowledge from this guide, you’re a step closer to keeping your lawn and garden safe.

If you need help controlling a cogongrass infestation on your land, check out this support resource from the Cogongrass Control Program.

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