Page Banner

United States Department of Agriculture

Agricultural Research Service

Research Project: Conservation Systems Research for Improving Evnironmental Quality and Producer Profitability

Location: National Soil Dynamics Laboratory

Title: Pushing towards cogongrass patch eradication: the influence of herbicide treatment and application timing on cogongrass rhizome elimination

Authors
item Aulakh, J -
item Enloe, S -
item PRICE, ANDREW
item Loewenstein, N -
item Wehtje, G -
item Patterson, M -

Submitted to: Invasive Plant Science and Management
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: March 21, 2014
Publication Date: N/A

Interpretive Summary: Cogongrass is an invasive grass native to Asia that has infested thousands of hectares in the southeastern US. A field study was conducted at two locations near Tillman’s Corner and Bayou La Batre in southwestern Alabama to evaluate specific herbicide treatments at spring, summer, and fall application timings for cogongrass patch eradication. Results demonstrate for the first time that the entire rhizome layer of cogongrass can be eliminated with multiple treatment options within three years and that cogongrass patch eradication is possible for many land managers.

Technical Abstract: Cogongrass is an invasive grass native to Asia that has infested thousands of hectares in the southeastern US. While numerous studies have examined cogongrass control, no published studies have tested strategies for cogongrass eradication. Since cogongrass has a persistent, thick, rhizome mat and ephemeral seedbank, successful eradication methods must largely focus on the rhizome issue. A field study was conducted at two locations near Tillman’s Corner and Bayou La Batre in southwestern Alabama to evaluate specific herbicide treatments at spring, summer, and fall application timings for cogongrass patch eradication. Herbicide treatments included glyphosate at 4.48 kg ai ha-1, imazapyr at 0.84 kg ai ha-1 and a tank mix of glyphosate and imazapyr at the same rates. The three application times were May, August and October and treatments were applied at each timing for three consecutive years. Cogongrass visual control, vegetative cover, shoot and rhizome biomass, and rhizome depth and energy content were sampled over the course of the study. Cogongrass response to treatments varied by location but by 36 months after initial treatment (MAIT), complete elimination of cogongrass shoot and rhizome biomass, and 100 % visual control was achieved in several herbicide treatment timing combinations at both locations. These included glyphosate + imazapyr treatment at any application timing, imazapyr treatment in August or October, and glyphosate treatment applied in May and October of each year. Total nonstructural carbohydrate (TNC) levels of healthyrhizomes were not affected by herbicide treatments but a seasonal pattern was observed. The maximum live-rhizome depth was not influenced by any treatment, indicating that herbicides were not preferentially leaving deeper surviving rhizomes. These results demonstrate for the first time that the entire rhizome layer of cogongrass can be eliminated with multiple treatment options within three years and that cogongrass patch eradication is possible for many land managers.

Last Modified: 9/10/2014
Footer Content Back to Top of Page