Science You Can Use
Has cogongrass invaded your land? The first step — and the easiest — is identifying the plant itself, which the U.S. federal government and multiple states list as a noxious weed.
Cogongrass has some features that make it fairly easy to identify. Compared to the deep green hues of other grasses typically found in the South, the leaves of cogongrass appear yellowish green, and the white upper midrib of the leaves tends to be slightly off center. The short nondistinct stems and the leaves appear to arise directly from the soil.
Cogongrass flowers in the spring — earlier than most other grasses — in a striking display of fluffy silvery-white seed heads. Also distinctive is the pattern of spread: patches of cogongrass often radiate outward in circular patterns that remain obvious even when the plants turn brown in winter. The Forest Service and Bugwood.org have produced a printable identification guide you can use in the field.
If you suspect cogongrass is growing on your land, contact your local forestry commission or county extension office as soon as possible for positive identification and to develop an eradication strategy. Since cogongrass is a federally listed noxious weed and is also listed as such by most southern states, state forestry and agriculture agencies will often carry out or assist in its eradication and control. Do not try to burn cogongrass infestations without first consulting these experts.
Some tips for controlling cogongrass:
- Minimize disturbance within miles of where cogongrass occurs. Anticipate its spread.
- Treat cogongrass infestations as soon as possible. Young infestations are much easier to control than those that are older and well established.
- Effective and safe herbicides are available for cogongrass control, but remember that it’s possible to kill or injure nontarget plants when using herbicides.
- Burning and mowing can improve the efficiency of herbicide treatments. However, burning can kill native shrubs and trees that constrain spread and may actually cause cogongrass infestations to expand more rapidly.
- Mowing, burning, or treating cogongrass with herbicides in early growth stages, during early flowering, or even shortly before flowering can stop seed production. Again, a caution: these treatments may also cause flowering and seeding.
- After working in a cogongrass-infested area, thoroughly clean all equipment and personnel to remove cogongrass seeds and rhizomes.
- Do not plant the ornamental cogongrass cultivars (Japanese blood grass and Red Baron). If a cultivar has been planted, remove the plantings, and control sprouts and seedlings.
- Repeated cultivation and planting of aggressive native grasses or other crops can restore pastures and croplands impacted by cogongrass infestation.
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