Bermudagrass - A lingering problematic weed in Louisiana sugarcane

Authors: Spaunhorst, Douglas; ORGERON, ALBERT - LSU Agcenter

Submitted to: Sugar Journal
Publication Type: Trade Journal
Publication Acceptance Date: 4/1/2018
Publication Date: 5/1/2018
Citation: Spaunhorst, D.J., Orgeron, A.J. 2018. Bermudagrass - A lingering problematic weed in Louisiana sugarcane. Sugar Journal. 80(12):10-13.

Interpretive Summary:

Technical Abstract: Prior to the 1900s methods to control weeds were comprised of cultivation and hand-weeding. Over the past century, herbicides have become an important component for managing weeds. Many herbicides developed for commercial use target weeds that are problematic in cereals, corn, soybean, rice, cotton, and other commodities that are grown on millions of acres of land. The potential return on investment for these crops is much greater than for minor crops, such as sugarcane. Fortunately, sugarcane is a crop that exhibits considerable tolerance to many herbicides used to control weeds in other crop markets, in particular those herbicides developed for the corn market. This creates an opportunity for herbicide registrants to add additional crops, such as sugarcane, to their proposed herbicide label provided that herbicide residues do not exceed tolerance levels mandated by the EPA. Perennial gramineous weeds are some of the most difficult to control in sugarcane. Bermudagrass, a perennial grass, is among the most problematic weeds encountered by sugarcane producers in Louisiana. The initial management of bermudagrass should be address during the fallow period prior to the establishment of sugarcane. Application of glyphosate followed by cultivation two to three weeks after a treatment of glyphosate should be repeated at least twice during the fallow period to maximize bermudagrass control. Control of bermudagrass and other perennial weeds throughout the fallow period and at sugarcane planting, by using pre emergence herbicides, ensures that newly planted sugarcane will have few competitors upon emerging from the soil. Once sugarcane is established, there are no herbicides that result in commercially acceptable bermudagrass control throughout the course of the growing season. Bermudagrass established on top of the hipped row is more difficult to manage compared to bermudagrass in the wheel furrow, as herbicides are the only tool for weed suppression. However, some herbicides can result in bermudagrass suppression for a period of four to six weeks. Research shows that the herbicide active ingredients clomazone, terbacil, trifluralin (must be soil incorporated), and hexazinone all result in partial bermudagrass suppression, but the key here is suppression and not control. Following bermudagrass suppression by the former herbicides, the formation of a dense sugarcane canopy can serve as an additional tool to help manage bermudagrass. When herbicides and shading are used in conjunction with each other there is greater potential to manage the weed than either method used alone. Successful management of bermudagrass will require a holistic approach that includes use of herbicides, cultivation, planting cultivars that emerge rapidly and shade out weeds early in the growing season. An integrated weed management approach is necessary for successful cultivation of sugarcane in Louisiana for generations to come.