A NOVEL APPLICATION OF THE HERBICIDE ETHOFUMESATE TO INCREASE AND PROLONG THE EFFECTIVENESS OF GLYPHOSATE RESISTANT TECHNOLOGY IN SUGARBEET

• Sponsoring Institution: National Institute of Food and Agriculture
• Project Status: COMPLETE
• Funding Source: HATCH
• Reporting Frequency: Annual
• Accession No.: 0213038
• Project Start Date: Jan 1, 2008
• Project End Date: Sep 30, 2010
• Program Code: [(N/A)]- (N/A)

Recipient Organization
UNIVERSITY OF WYOMING
1000 E UNIVERSITY AVE DEPARTMENT 3434
LARAMIE,WY 82071-2000

Performing Department
PLANT SCIENCES

Non Technical Summary
Glyphosate resistant sugarbeet represents the most significant technological advance in sugarbeet weed management since the introduction of selective herbicides. Unavailability of currently used postemergence herbicides, hesitance to use preemergence herbicides, and reluctance to use tillage for weed control in the glyphosate resistant sugarbeet crop could potentially result in near total reliance on a single herbicide for weed management in the glyphosate resistant sugarbeet crop. Reliance on a single herbicide will almost surely lead to glyphosate resistant weeds, and by the time glyphosate resistant weeds appear in Wyoming sugarbeet fields, growers will have few acceptable management options. It is therefore imperative that this technology be utilized prudently, and proactive management strategies put in place in order to prolong the utility of the technology well into the future. We propose a novel use of a herbicide currently registered for weed control in sugarbeet in order to increase the effectiveness and prolong the utility of glyphosate resistant technology in sugarbeet. Ethofumesate is widely used as a preemergence herbicide on conventional sugarbeet acres in Wyoming and the US. The use rate of ethofumesate required to achieve adequate weed control often results in injury to the sugarbeet crop. Previous research has demonstrated that preemergence application of ethofumesate can increase uptake of subsequently applied herbicides. The goal of this research project is to determine whether ethofumesate can be applied to glyphosate resistant sugarbeet at a rate low enough to minimize crop injury, but still provide an economic weed control benefit by increasing uptake, and therefore increasing the efficacy, of subsequently applied glyphosate. If the findings of this research support our hypothesis, weed management programs will be more likely to include multiple herbicide modes of action for proactive resistance management, and provide better management of difficult to control weeds while reducing crop injury potential.

Animal Health Component

60%

Research Effort Categories

Basic

15%

Applied

60%

Developmental

25%

Classification

Knowledge Area (KA)	Subject of Investigation (SOI)	Field of Science (FOS)	Percent
205	2010	1140	30%
213	2300	1140	70%

Knowledge Area
205 - Plant Management Systems; 213 - Weeds Affecting Plants;

Subject Of Investigation
2010 - Sugar beet; 2300 - Weeds;

Field Of Science
1140 - Weed science;

Keywords

glyphosate

roundup ready

ethofumesate

nortron

herbicide resistance

sugarbeet

sugar beet

beta vulgaris

Goals / Objectives
The goal of this research is to quantify and characterize the interaction between sequential or tank-mix applications of ethofumesate and glyphosate in order to provide information on management of glyphosate resistant sugarbeet to growers in Wyoming, Colorado, and across the US. Specifically, we intend to: 1) determine whether synergistic, additive, or antagonistic interactions exist between ethofumesate and glyphosate; 2) obtain qualitative data on the disruption of sugarbeet and common lambsquarters leaf epicuticular waxes by ethofumesate; 3) determine whether disruption of leaf waxes by ethofumesate allows increased retention and penetration of glyphosate; 4) determine a rate of ethofumesate that will provide weed control benefit when combined with postemergence glyphosate applications with minimal phytoxicity to the sugarbeet crop; 5) determine the optimal timing of ethofumesate application in relation to glyphosate applications.

Project Methods
Greenhouse dose response studies will be conducted to accomplish Specific Objective 1, and provide preliminary data to inform research to address Specific Objectives 3 through 5. Since very little data exists describing the combined effects of ethofumesate with glyphosate, it is important that the interaction be characterized with respect to weed control as well as sugarbeet injury. The experiment will be set in a factorial completely randomized design with 5 replicates. Data will be analyzed using non-linear regression techniques. The dose of glyphosate that effectively controls 90% of the common lambsquarters plants (ED90) will be quantified for each rate of ethofumesate applied preemergence or postemergence. Likelihood ratio tests will be conducted to determine whether the herbicides interact in an additive, synergistic, or antagonistic manner, and whether the interaction is the same between ethofumesate application timings. The effect on sugarbeet plants (ED10) will also be quantified in order to evaluate crop safety for each rate combination. Qualitative evaluation of wax disruption by ethofumesate will accomplish Specific Objective 2, and provide preliminary data to inform research to address Specific Objectives 3 and 5. little information exists on the dose required to illicit a given level of wax disruption, or the time required following ethofumesate application to achieve substantial wax disruption. We will use methods similar to Sylvester et al. (2001) in order to view changes in the epicuticular waxes of sugarbeet and common lambsquarters following application of ethofumesate. Dental wax impressions will be taken from the adaxial leaf surface of plants of both species at various time points prior to and following ethofumesate application. A positive impression will then be made by applying epoxy resin to the mold created by the dental wax. The impression will then be viewed with scanning electron microscopy in the UW Microscopy facility. Quantification of glyphosate absorption in response to ethofumesate treatment will accomplish Specific Objective 3. The rates and timings to be used in this study will be chosen based on results from field, greenhouse, and laboratory research. Common lambsquarters and sugarbeet plants will either not be treated with ethofumesate (control) or be treated with ethofumesate at one of two timings (preemergence and postemergence) that are chosen. 14C-glyphosate will then be applied to all plants once they reach the two to four true-leaf stage of growth. The location of 14C-glyphosate will then be monitored at 3 time points following application. Data will be subject to a factorial ANOVA and presented as percent of the total recovered radioactivity. Field studies will accomplish Specific Objectives 4 and 5. Field and greenhouse research will be used to choose the best subset of treatments to be included at each field location.

Progress 01/01/08 to 09/30/10

Outputs
OUTPUTS: During the course of this project, presentations describing the results have been given locally, regionally, and nationally, including: Field tours at Research and Extension Centers near Lingle and Laramie, Wyoming; grower presentations in Worland, Powell, and Casper, Wyoming, and Billings, Montana; scientific presentations at the North Central Weed Science Society, American Society of Sugar Beet Technologists, and Weed Science Society of America. A manuscript reporting on the laboratory and field trials is nearly complete and will be submitted to a peer-reviewed journal within a year. PARTICIPANTS: Andrew Kniss (PI) was the project leader, and has taken a leadership role in design, analysis, publication, and presentation of results. Dennis Calvin Odero (Postdoctoral Research Associate) conducted a majority of laboratory experiments and aided in all field trials. Dr. Odero presented the results to scientists and growers throughout the project. Dr Odero received training in the areas of light microscopy, nonlinear regression analysis, and non-destructive leaf sampling techniques. Abdel Mesbah (Co-PI) aided in project design, and was responsible for conducting field studies. Scott Nissen (Co-PI) aided in project design. David Claypool aided in many of the field and laboratory trials. Western Sugar Cooperative (partner organization) has shown interest in the results, and has agreed to fund additional research to expand on results obtained during the course of this project. Training has been provided to one postdoctoral research associate, several graduate students, and the results have been utilized in undergraduate teaching as part of Dr. Kniss's Weed Science and Technology (PLNT 4070/5070) course to illustrate sequential herbicide interactions. TARGET AUDIENCES: The target audience for this project is primarly sugarbeet growers in the high plains production region who are utilizing glyphosate-resistant sugarbeet, but also weed scientists who work in similar systems. Efforts to reach this audience have included numerous field day and training presentations, as well as presentations at regional and national professional societies. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.

Impacts
These studies have demonstrated for the first time that use of ethofumesate prior to weed emergence increases retention of herbicides that are applied subsequently, and can therefore increase the efficacy of those postemergence herbicides. This knowledge has been of great interest to sugarbeet growers and scientists alike. Presentations have been made to over 300 sugarbeet growers within the last year, and it is expected that growers will consider changing production practices based on the results of these studies. When adopted, these practices will help to protect a technology that has been valued at nearly $7 million to Wyoming sugarbeet growers.

Publications

• Kniss, A.R. and D.C. Odero. 2011. Preemergence ethofumesate increases postemergence spray retention on common lambsquarters. Journal of Sugar Beet Research (Abstract). 48(1&2):52.
• Odero, D.C. and A.R. Kniss. 2009. Interaction of ethofumesate and glyphosate for weed control in glyphosate-resistant sugarbeet. Proc. North Cent. Weed Sci. Soc. 64:181.
• Odero, D.C., A.R. Kniss, and A.O. Mesbah. 2009. Common lambsquarters control with glyphosate and ethofumesate in glyphosate-resistant sugarbeet. Proc. Western Soc. Weed Sci. 62:152.
• Kniss, A.R. and D.C. Odero. 2010. Preemergence ethofumesate increases postemergence spray retention on common lambsquarters. Proc. North Cent. Weed Sci. Soc. 65:105.
• Odero, D.C., and A.R. Kniss. 2010. Reduced rates of ethofumesate for use in glyphosate resistant sugarbeet. Proc. Weed Sci. Soc. Am. P A-24.

Progress 01/01/09 to 12/31/09

Outputs
OUTPUTS: Outputs for the first year of this project include training of a postdoctoral research associate, one graduate student, and two undergraduate students in methodologies associated with herbicide dose-response studies herbicide retention analysis. Results of greenhouse and field studies were presented to producers and extension personnel at two extension field tours and one sugarbeet grower meeting, and to other researchers at the North Central Weed Science Society annual meeting. PARTICIPANTS: Andrew R. Kniss, Assistant Professor; Abdel O. Mesbah, Director, Powell R&E Center; Scott Nissen, Professor, Colorado State University; David A. Claypool, Master Technician; Calvin Odero, Postdoctoral Research Associate; Randy Violett, Research Associate; Jared Unverzagt, Undergraduate Research Assistant; Cole Brandon, Undergraduate Research Assistant; Nevin Lawrence, Graduate Research Assistant. TARGET AUDIENCES: In the second year of this project, the target audience has been sugarbeet growers and agriculturalists, other sugarbeet researchers, undergraduate and graduate students, and extension personnel. PROJECT MODIFICATIONS: No major modifications have been made to this project.

Impacts
Outcomes to date involve extension of knowledge from the first two years of the project to end users of the information. Based on field studies, it was found that reduced rates of ethofumesate applied preemergence (0.28 kg/ha) reduced redroot pigweed and common lambsquarters densities by 61 and 40%, respectively. When added to the first postemergence application of glyphosate, ethofumesate at 0.28 kg/ha reduced redroot pigweed, common lambsquarters, and hairy nightshade densities by 61, 32, and 16%, respectively, compared to glyphosate alone. These results indicate that significant weed control benefit can be observed from this herbicide at rates that cause little to no crop injury. These results have been presented to end-users of the technology. Subsequent extension and education efforts will be aimed at increasing awareness of this information for use by sugarbeet growers.

Publications

• Odero, D.C. and A.R. Kniss. 2009. Interaction of ethofumesate and glyphosate for weed control in glyphosate-resistant sugarbeet. Proc. North Cent. Weed Sci. Soc. 64:181.

Progress 01/01/08 to 12/31/08

Outputs
OUTPUTS: Outputs for the first year of this project include training of a postdoctoral research associate in methodologies associated with herbicide dose-response analysis and non-destructive leaf microscopy. Preliminary results of greenhouse studies were presented at the annual meeting of the Western Society of Weed Science in March, 2009. PARTICIPANTS: Andrew R. Kniss, Assistant Professor; Abdel O. Mesbah, Director, Powell R&E Center; David A. Claypool, Master Technician; Calvin Odero, Postdoctoral Research Associate; Randy Violett, Research Associate; Jared Unverzagt, Undergraduate Research Assistant; Cole Brandon, Undergraduate Research Assistant. Training was provided to one postdoctoral research associate and two undergraduate students as part of this project (Odero, Unverzagt, and Brandon). TARGET AUDIENCES: In the initial year of this project, the target audience has been other researchers and students. As the knowledge is translated to the field, the target audience will include sugarbeet growers and agriculturalists as well. PROJECT MODIFICATIONS: No major modifications have been made to this project.

Impacts
Based on greenhouse studies, it was determined that when ethofumesate and glyphosate are applied in combination, they act in an additive fashion on common lambsquarters. This knowledge will aid in designing field studies to further evaluate the interaction of these two herbicides. Since it is the first year of this project, most outcomes to date involve development and refining of research methodologies. For example, non-destructive leaf microscopy methods that have been used successfully in maize have been modified for use in common lambsquarters. These methods will soon allow us to accomplish our objective of determining the optimal rate and timing of ethofumesate in relation to glyphosate applications. Methods to evaluate glyphosate retention in common lambsquarters following pre-treatment with ethofumesate are also underway. Adverse environmental conditions limited the value of field studies conducted in 2008, however, the results of greenhouse work will allow for refined field studies to go on as planned in 2009.

Publications

• Odero, D.C., A.R. Kniss, and A.O. Mesbah. 2009. Common lambsquarters control with glyphosate and ethofumesate in glyphosate-resistant sugarbeet. Proc. Western Soc. Weed Sci. 62:152.