Giant ragweed is the second most problematic weed in Minnesota soybean after waterhemp. Common ragweed is also recognized by soybean growers as a difficult-to-control weed.
Ragweeds are the early-emerging species and there are not many effective preemergence herbicides available in soybean for early-season control of these weeds. Moreover, most of those preemergence herbicides can cause carryover injury to subsequent crops like sugar beet. The presence of herbicide-resistant ragweeds has previously been reported in Minnesota and the spread of those populations is limiting the herbicide choices for soybean growers.
Therefore, taking an integrated weed management (IWM) approach that includes cultural and mechanical weed control tactics along with herbicide application will be important. Fall- planted cereal rye cover crop can suppress weeds in soybean by obtaining sufficient biomass. Several of our ongoing research trials showed that delaying cover crop termination by one week after soybean planting (“planting green”) can show a positive impact on weed control without negatively impacting the soybean yield. Previous studies reported that spring tillage or burndown herbicide application before soybean planting can substantially reduce ragweed density. However, very limited data is available in the literature on the effect of cover crops on ragweed control and density. Also, the interaction of cover crops and preemergence herbicides are also not well-understood. The objective of this research is to evaluate the impact of integrated weed management tactics for giant and common ragweed control and soybean yield. Experiments will be conducted in Rosemount, MN and Crookston, MN in 2023 and 2024.

1. GOAL: Evaluate the effect of integrated weed management tactics on herbicide- resistant giant ragweed and common ragweed control, soybean growth, and yield

OBJECTIVE: This project will evaluate the impact of integrated weed management tactics that include tillage, cover crops, and herbicide application on ragweed control, density, and soybean yield in Rosemount and Crookston, MN.

This team comprises three faculty (Sarangi, Peters, and Johnson) and a Regional Extension Educator (Peltier). Sarangi and Peters are the Extension Weed Specialists at UMN impacting statewide corn, soybean, and sugar beet acreages, and Peltier is one of the key personnel at UMN that reaches out to growers, crop advisors, and other stakeholders every day to advise them on weed and other pest management in northwest Minnesota and has researched winter rye, winter camelina and brown mustard as cover crops in northwest Minnesota. Johnson is a weed ecology and cover crop specialist with several years of research experience on different cover crop species and their ability to suppress weeds in corn-soybean systems. The results of this research will be demonstrated in summer Field Days in Rosemount, MN in 2023 and in Crookston, MN in 2024. The information obtained from this research will also be disseminated using web-based platforms, including but not limited to, the MN Crop News (over 1,600 subscribers), regional Extension Crop newsletters, radio spots, the Strategic Farming webinar series, and Minne-Line articles. Social media platforms such as Twitter, Facebook, and YouTube will also be used to share research updates and short videos. The results will be presented at Extension events such as the Crop Pest Management (CPM) Short Course, Research Update for Ag Professionals, the Prairie Grains Conference, the Best of the Best in Wheat & Soybean Research Conference, and the Minnesota Ag-Expo. Most of the audience at these events are agronomists, farmers, fertilizer/plant protection dealers, and independent crop consultants. One graduate student (50% salary, and tuition is requested) will be mentored as a part of this project and this research will be part of their thesis work. Peer-reviewed journal articles will be published from this research.

Update:
Please find the attached file

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Update:
Attached. Not much things changed in this project since last quarter's report.

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Updated June 3, 2024:
Attached.

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The proposed research will evaluate integrated management tactics for giant ragweed and common ragweed control in soybean. Ragweeds can reduce soybean yield significantly if proper management tactics are not implemented. Also, ragweed seed is one of the major contributors to the foreign materials in US-grown soybean. With the rise of multiple herbicide resistance in Minnesota, it will be very difficult to manage these weeds with only herbicide applications in the future. Also, there are not many effective preemergence herbicides available in soybean for ragweed control. Therefore, the approach of integrated management of ragweeds will provide additional tools for farmers to control these weeds effectively in soybean. The goals outlined in this research are timely and need immediate attention. This research will also be replicated in two locations (Rosemount and Crookston, MN) in the state, and those locations vary with their weather, soil types, weed species, and farming practices. Our ultimate goal is to increase soybean yield and quality, and farm profitability.