Influence of topramezone plus triclopyr mixtures and application timing on bermudagrass control in sugarcane

Authors: Spaunhorst, Douglas

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 9/1/2019
Publication Date: 9/23/2019
Citation: Spaunhorst, D.J. 2019. Influence of topramezone plus triclopyr mixtures and application timing on bermudagrass control in sugarcane [abstract]. International Society of Sugarcane Technologists 3rd Agricultural Engineering, Agronomy and Extension Workshop, September 23 - 28, 2019, La Reunion Island. p. 49

Interpretive Summary:

Technical Abstract: Bermudagrass remains one of the most troublesome perennial weeds to control in sugarcane. Previous research has shown increased herbicidal activity with mixtures of topramezone plus triclopyr on bermudagrass in tall fescue turf. Limited data is available on sugarcane yield response and bermudagrass control with topramezone plus triclopyr mixtures. The first objective of this study was to evaluate the single herbicide treatments: topramezone (24.5 g ai ha-1) plus triclopyr (1,130 g ae ha-1), topramezone (24.5 g ai ha-1) plus triclopyr (1,130 g ae ha-1) plus asulam (1,850 g ae ha-1), and topramezone (24.5 g ai ha-1) plus triclopyr (1,130 g ae ha-1) plus trifloxysulfuron (15.8 g ai ha-1). A sequential treatment of topramezone (24.5 g ai ha-1) plus triclopyr (1,130 g ae ha-1) was applied 3 weeks after treatment to plots that were treated to the previously listed herbicide mixtures, and bermudagrass control was evaluated. The second objective was to determine if bermudagrass infestation level at the time of herbicide treatment influences herbicide efficacy for control of bermudagrass and sugarcane yield components and the third objective was to evaluate if additional bermudagrass control can be achieved with the addition of asulam or tryfloxysulfuron to topramezone plus tryclopyr to create a three-way herbicide mixture. Sequential herbicide treatments reduced green bermudagrass biomass and bermudagrass cover 4 and 43% more than single herbicide treatments, respectively, and had no negative impact on sugarcane yield and sucrose yield. Delaying the herbicide treatment timing until bermudagrass infestation reached 100% resulted in 21% less green bermudagrass biomass compared to herbicide treatments applied at 25% bermudagrass infestation. Increased control is likely attributed to having less time for bermudagrass to recover from the herbicide treatment before the row middles were shaded out by the crop canopy. Sucrose yield is a function of theoretical recoverable sucrose and sugarcane biomass yield. Herbicide treatments did not reduce sugarcane yield, but some treatments reduced sucrose yield. The three-way mixture of topramezone plus triclopyr plus asulam resulted in 11% greater sucrose yield than the two-way topramazone plus triclopyr mixture, but was similar to the topramezone plus triclopyr plus trifloxysulfuron mixture. Results from this study show plant cane (cultivar L 01-299) is highly tolerant to bermudagrass competition, as sucrose yield recorded from the nontreated check was equal to or greater than sucrose yields from herbicide treated plots. Additional research is needed to determine the effect of bermudagrass competition on subsequent ratoon yield and to evaluate other commonly planted sugarcane cultivars yield response to topramezone plus triclopyr mixtures.