Revised by Joey Williamson, HGIC Horticulture Extension Agent, Clemson University, 10/15. Prepared by Joey Williamson, Ph.D., HGIC Horticulture Extension Agent, Clemson University. New 11/08. Images added 3/09.
Cogongrass (Imperata cylindrica) is one of the world’s ten worst weeds and has already invaded 153 billion acres worldwide. Cogongrass is becoming established in Florida, Georgia, Alabama, Mississippi and Louisiana, and has now been found in South Carolina. In Florida alone, it has infested one million acres, where it has displaced many native species of plants. Cogongrass will invade pastures, where it reduces the forage quality because its leaves are unpalatable to livestock. It can quickly displace other vegetation in forests and fields, including native plants that birds and small animals need for shelter and forage.
Cogongrass (Imperata cylindrica) in bloom in early summer.
Fred Singleton, Department of Plant Industry, Clemson University
This weed spreads not only by an aggressive root system, but also by fluffy white seed heads that produce an abundance of wind-blown seed in the early summer. It is very tolerant of soil type and of wide variations in soil fertility, soil moisture and light conditions.
Cogongrass (Imperata cylindrica) seedheads appear in early summer.
Steve Compton, Department of Plant Industry, Clemson University
Cogongrass has sharp-pointed leaf blades which are ¾ to 1 inch wide, and the main vein of each leaf is off-center and white.
For more information on cogongrass identification, please see: www.cogongrass.org/identification
Notice the off-center, white, main vein in cogongrass leaves (Imperata cylindrica).
Mark Atwater, Weed Control Unlimited, Inc., US
Japanese bloodgrass (Imperata cylindrica ‘Red Baron’) is a 2-foot tall perennial grass with red and lime-green leaves. The problem is that Japanese bloodgrass (‘Red Baron’ bloodgrass) is a variety of cogongrass, and this red-leafed ornamental grass can revert back to the extremely aggressive, 4 to 5 foot-tall, green form. Sales of this popular ornamental grass have been halted in South Carolina, but plants have been brought in from other states. Although this grass might make a nice colorful addition to the perennial garden, it’s highly aggressive nature warrants us to think twice about planting it.
Japanese bloodgrass (Imperata cylindrica ‘Red Baron’).
Karen Russ, ©2009 HGIC, Clemson Extension
For gardeners who would like to have a red-leafed ornamental grass in their perennial beds, there are other choices. There are several cultivars of our native switchgrass (Panicum virgatum) that have red foliage, which is especially prominent in mid-summer through fall. The species and the cultivars of switchgrass are non-invasive plants and form clumps that slowly spread by creeping rhizomes. They grow best in full sun gardens and are adapted to a wide range of soil conditions. These switchgrasses grow well in USDA zones 4 to 9.
Panicum virgatum ‘Shenandoah’.
Karen Russ, ©2009 HGIC, Clemson Extension
Clemson University’s Department of Plant Industry is a member of a task force, which includes the SC Forestry Commission and the US Forest Service, with the goal of preventing the spread of cogongrass within South Carolina. If you have Japanese bloodgrass or have seen cogongrass in your area, contact the Clemson Department of Plant Industry at 864-646-2140. Any sighting will be investigated.
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This information is supplied with the understanding that no discrimination is intended and no endorsement of brand names or registered trademarks by the Clemson University Cooperative Extension Service is implied, nor is any discrimination intended by the exclusion of products or manufacturers not named. All recommendations are for South Carolina conditions and may not apply to other areas. Use pesticides only according to the directions on the label. All recommendations for pesticide use are for South Carolina only and were legal at the time of publication, but the status of registration and use patterns are subject to change by action of state and federal regulatory agencies. Follow all directions, precautions and restrictions that are listed.