PRE herbicides are essential components of a soybean weed management program, even when planting occurs earlier than traditional. However, the potential for soybean injury from PRE herbicides can be increased in early-planted systems. Cold, wet soil conditions can delay soybean seed germination and prolong the duration of soybean emergence, thereby increasing the duration of exposure to the PRE herbicides. These conditions also reduce the soybean plant’s ability to rapidly metabolize the herbicide, further increasing the potential for injury. Anecdotal conversations with early soybean planting practitioners have revealed some general reluctance to use certain herbicide chemistry classes for fear of enhanced soybean injury. Our previous research included only one commercial PRE herbicide because the focus of that research was to establish weed management concepts. This proposed research will take the next step in understanding weed management in early-planted soybean by investigating soybean injury potential from several commercially available PRE herbicides. Results of this research will better inform soybean producers about which herbicides or herbicide classes they might want to avoid in early-planted soybean scenarios. The 2025 growing season will be the second year of this two-year research project.

Field research will be conducted for two growing seasons at the Crop Sciences Research and Education Center. Treatments will include 12 commercially available herbicide premixes that span 10 herbicide active ingredients encompassing five site-of-action groups. Each herbicide will be applied at its respective 1x rate according to label directions for soil type and organic matter content. All treatments will be applied immediately after soybean planting in late March or early April each season. The experiment will be located on an area with an historically low weed density to reduce a potentially confounding effect on soybean yield. A nontreated control will be included for comparison.

This research will generate data necessary to formulate herbicide-specific recommendations in very early planted soybean. Treatments in our previous experiment were designed more to test research concepts than individual product performance against weeds. This research will build upon our experiences with early-planted soybean and provide us with the ability to make research-based herbicide recommendations that minimize the potential for soybean injury. The experience gained from this research project will guide future research in very early-planted soybean, such as including a cover crop, soybean row spacing for optimal weed control, etc.

Results of this research will better inform soybean producers about which herbicides or herbicide classes they might want to avoid in early-planted soybean scenarios.