2017
Integrated Strategies to Manage Herbicide Resistant Weeds in MD Soybean Systems
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Contributor/Checkoff:
Maryland Soybean Board
Category:
Sustainable Production
Keywords:
AgricultureCrop protectionHerbicide
Parent Project:
This is the first year of this project.
Lead Principal Investigator:
Benjamin Beale, University of Maryland
Co-Principal Investigators:
Project Code:
Contributing Organization (Checkoff):
Maryland Soybean Board
$6,457
Institution Funded:
University of Maryland
$6,457
Brief Project Summary:

Herbicide resistance continues to be a major concern for Maryland soybean growers, particularly with palmer amaranth, common ragweed, common waterhemp and marestail. Previous research demonstrated the efficacy of various pre-emergent herbicide treatments for Palmer amaranth control. This research continues investigating strategies that will provide season-long control of Palmer amaranth. It evaluates combinations of pre-emergent herbicides with delayed early post residual herbicides and timed post-emergence herbicides. It continues to include evaluation of burndown treatments prior to planting, and evaluation of pre-emergent herbicides for confirmed ALS resistant common ragweed.

Key Benefactors:
farmers, agronomists, Extension agents

Information And Results
Project Deliverables

1. Report detailing the results of field trials comparing various herbicide treatments and identifying those treatments which were most effective at controlling target weeds.
2. Field demonstration days were conducted each year at the trial locations to demonstrate trial results, weed identification and management techniques.

Final Project Results

Update:
Herbicide treatments
Results from the 2017 trial are consistent with findings in 2015 and 2016. The trials indicate significantly better control of Palmer amaranth with the use of any residual product when compared to a non-treated control. Prowl, Dimetric, and Prowl plus Dimetric provided 1-2 weeks of control, Boundary and Canopy provided 2-3 weeks of control and Fierce, Fierce XLT, Authority XL, and BroadAxe XC provided 3-5 weeks of control. The trial did not show significant differences between treatments that received an additional post-emergence application of the residual herbicide Dual. The use of residual products also provided a longer timeframe for the timely and thus effective application of post-emergent herbicides. The trials show that a post-emergent herbicide treatment needs to be applied within 28 days of planting to achieve reliable control. Waiting beyond 28 days will result in emerged Palmer amaranth plants that are larger than the 3-4 inch height limit for post-emergent herbicides. If no residual herbicide is used, the post-emergent treatments need to be applied within 14 days, and season long control is very unlikely.

Ragweed trials
The trial indicates significantly better control of common ragweed with the use of any residual product when compared to a non-treated control. Treatments that utilized more than one effective mode of action provided better control then single mode of action treatments. Products containing the active ingredients linuron, metribuzin, and flumioxazin performed best. Command (clomazone) performed significantly better than the control, but was not as effective as other products. There was some plant stunting and phytotoxicity observed on plots treated with Linex plus Dimetric.

View uploaded report Word file

Results indicate significantly better control of Palmer amaranth with the use of any residual product when compared to a non-treated field. The length of control provided by residual products varied from two to six weeks. Products with the active ingredient flumioxazin including premixes of Fierce or Fierce XLT or products with the active ingredient sulfentrazone including premixes such as Broadaxe or Authority XL provided the most consistent control. Residual herbicides also resulted in differences in weed height over the length of the season. This is especially advantageous in that it provides a longer timeframe for the timely and thus effective application of post-emergent herbicides.

The United Soybean Research Retention policy will display final reports with the project once completed but working files will be purged after three years. And financial information after seven years. All pertinent information is in the final report or if you want more information, please contact the project lead at your state soybean organization or principal investigator listed on the project.