By Ken McMillan-Chambers County Extension Coordinator
A Chambers County landowner recently had an unwelcomed visitor – Cogongrass. Cogongrass is an aggressive exotic perennial grass that was introduced to Mobile, Alabama in 1911. It was used in packing material from Japan. Cogongrass is spreading rapidly across Alabama, reducing forest productivity, destroying wildlife habitat, and encroaching in pasture and hayland acreage. Cogongrass can quickly become the dominant understory plant which can outcompete the desired vegetation. Cogongrass is highly flammable and creates a severe fire hazard, especially in drought conditions and the winter. The extreme temperatures generated when cogongrass burns can kill seedling trees and native plants. Dense stands of cogongrass will also destroy wildlife habitat by out-competing native grasses and forbs utilized as forage.
Cogongrass forms patches in a circular pattern. It grows in full sunlight to partial shade and varies in height from 1 to 4 feet. Leaves measure .5- to 1-inch wide and are commonly 12 to 30 inches long. The whitish upper midrib of a mature leaf is often not centered on the blade. Leaf margins are rough to the touch due to tiny serrations. The leaves appear to grow directly from the soil, but short stems are present. The plant is hairless except where a few short hairs can be found at the node (where the leaf grows from the stem). Seed heads (fluffy, white, plume-like) range from 2 to 8 inches in length and appear in late spring, early summer, or after a disturbance. Each seed has silky, white hairs that are wind dispersed. Rhizomes of cogongrass are white, segmented, branched, and are sharp pointed and often pierce the roots of other plants.
Tillage can eliminate new patches of Cogongrass if continued during the growing season. Herbicides with the active ingredients Glyphosate and Imazapyr have been used to effectively control established stands of cogongrass; however, the plant often regenerates within a year following a single application. A minimum of two applications per year is needed, with older infestations requiring 2 to 3 years of treatment to eliminate rhizomes. Herbicide labels specify application methods, rates and precautions – which should be followed. Cogongrass is often spread throughout the state by contaminated equipment. To prevent spread of Cogongrass, do not mow, bush hog, or go through the grass when seed heads are present. Do not work in an infested area when soil is muddy, as rhizomes can break off and get stuck on equipment. Do not push roads or fire lanes or grade roads through cogongrass. If you must work in Cogongrass-infested areas, it is important to clean vehicles, equipment, and clothing before moving into an uncontaminated site.
For more information and Cogongrass photographs, please see Extension Publications ANR-1241 at http://www.aces.edu/pubs/docs/A/ANR-1241/ANR-1241.pdf and ANR-1321 at http://www.aces.edu/pubs/docs/A/ANR-1321/ANR-1321.pdf . If you have further questions or need assistance in identification, please contact your Chambers County Extension office (334-864-9373), Forestry Commission (334-864-9368), or NRCS (334-745-4791, ext. 3) office.