Non-GMO soybean is an important market for Michigan farmers. This market is particularly important as profit margins tighten. Premiums for non-GMO and other specialty non-transgenic soybeans often exceed $1.00 per bushel, and are currently close to $1.75. However, one of the greatest impediments to farmers of non-GMO soybean is good weed control. The MSPC has been a strong supporter of our weed management research for non-GMO soybean growers for several years. As herbicide-resistant horseweed (marestail) continues to plague Michigan farmers, we would like to expand on our non-GMO research to show the difference in non-GMO weed management programs between no-till and conventional tillage soybean, especially where horseweed is a problem. We are proposing to continue to develop effective, economically-sustainable weed management programs for Michigan’s non-GMO soybean growers.

These research and demonstration plots provides growers of non-GMO soybean with hands-on information on effective, sustainable weed control strategies. Additionally, alternative cost-effective weed control strategies in soybean may encourage growers to use other strategies for weed control to help delay the evolution of glyphosate and multiple-resistant weeds. This information may also serve as an opportunity for other Michigan farmers to grow non-GMO soybeans were a premium could be realized; therefore improving overall grower profitability.

1) Continue to develop and evaluate the effectiveness of several non-GMO weed control programs in tilled and no-till soybean.
2) Determine the economic returns of these weed control programs.
3) Provide this information specifically to non-GMO soybean producers through a web-accessible fact sheet, a field tour and at winter meeting specific to weed control in non-GMO crops.

Weed control, soybean injury, yield, and economic returns are used to rank the various weed control strategies available for use in non-GMO soybean. We are currently working on the economic analysis from the 2019 growing season to determine the most cost-effective of these programs. Premiums are included in the economic analysis. As mentioned earlier, these trials are good discussion points for growers at the MSU weed control tour, as well as for the 30+ non-GMO soybean growers that have attended the afternoon tours highlighting weed control in non-GMO soybean. The web-based fact sheets developed from this information are housed at the www.MSUweeds.com website and on the MSPC website if applicable. This information is also used at winter meetings that focus on weed control in non-GMO soybean.

Updated September 23, 2020:
Initial results and observations:
• The weed populations at the MSU Agronomy Farm were annual grasses (mainly giant foxtail and barnyardgrass), common lambsquarters, Powell amaranth, common ragweed, velvetleaf, and eastern black nightshade.
• Within two weeks of planting and PRE herbicide application there was over 1.25-inches of precipitation in multiple rainfall events. This rainfall thoroughly incorporated the PRE herbicides for excellent weed control. Due to warmer temperatures that lead to actively growing soybean, soybean injury was limited.
• Soybean injury from the PRE herbicides ranged from 3 to 13% ~21 DAP. The higher levels of injury were from treatments that contained the active ingredient flumioxazin (Valor) in some combinations with metribuzin, Surveil + metribuzin, Fierce MTZ, and Trivence. However, by the time of the POST application (~33 DAP) soybean injury was 4% or less except for Trivence were injury was 8%, illustrating soybean’s ability to recover from PRE herbicide applications.
• Weeds that escaped control from the PRE treatments was predominately common ragweed, and some annual grasses, and on occasion common lambsquarters and velvetleaf.
• Out of the 20 PRE herbicide treatments, four treatments provided excellent control at the time of the POST, so no POST was applied. These treatments were Sonic (6 oz) + Boundary (1.5 pt), Authority Edge (10 fl oz) + metribuzin (6 oz), Zidua PRO (6 fl oz) and Prefix (2 pt) + metribuzin (6 oz). By July 27, these treatments all provided >90% weed control.
• The POST herbicides following PRE treatments provided varying levels of soybean injury and weed control.
• Soybean injury from POST treatments ranged from 2-28%, 7 DAT. Cobra applied form 8 to 10 fl oz caused the greatest injury. By 28 DAT soybean injury was less than 2%.
• By 28 days after the POST treatments, all PRE followed by POST treatments provided greater than 90% control of all weed species.
• Common ragweed control was the species that was the least consistently controlled >90% with the PRE treatments. The fact that the common ragweed population was Group 2 (ALS)-resistant was the most challenging issue with some of the POST treatments. Additionally, Flexstar, Cobra, Marvel, and Ultra Blazer were used to clean up common ragweed escapes.
• Pictures and video have been taken throughout the season. We are hoping to highlight this research to non-GMO soybean growers this winter. Additionally, the web-accessible fact-sheet highlighting the economic returns of the different programs will be available soon after harvest.

This research provides growers with information on effective, sustainable weed control strategies in non-GMO soybean. The economic analysis is used to determine the cost-effectiveness of these strategies. With the increasing cost of soybean seed, particularly seed with herbicide-resistant traits, this information will provide growers with alternatives that may enhance their economics and potentially provide growers with alternative strategies for weed control to help delay the evolution of glyphosate-resistant weeds. This information could potentially open the doors for other growers to get into the production of soybeans were a premium could be realized; therefore improving overall grower profitability.