As herbicide-resistant weed varieties continue to spread across the United States, having an effective weed-management strategy is more essential than ever for soybean farmers. To develop such a strategy, it is important for farmers to have access to data measuring the effectiveness of different weed-control practices, which is precisely what the University of Wisconsin-Madison Weed Science program aims to provide.
The team found that using a diverse weed-management strategy had a significant effect on soybean yield.
“Fields with a herbicide resistance strategy of both preemergence herbicides and postemergence herbicides were six bushels to the acre better in yield,” explains Tommy Butts, a graduate research assistant at University of Wisconsin-Madison. “Additionally, these fields allowed only one tenth the amount of pigweeds compared to fields having only postemergence herbicides.”
Butts says using the one-two punch of preemergence and postemergence herbicides not only aids soybean development, it also significantly decreases the number of weeds exposed to the postemergence herbicide, which helps prevent weed species from developing resistance to herbicides.
“A big aspect of our study was trying to reduce the likelihood of herbicide resistance,” Butts said. “Every farmer needs to be concerned about herbicide resistance, and hopefully the results of our study will help back the idea that a diverse, multi-faceted herbicide strategy can help reduce weed numbers and improve yields.”
The project is based on enabling a field of soybean plants to take in as much sunlight as possible and keep that light away from weed plants. Partially funded by the soy checkoff, the research measures how well different row widths, seeding rates, and herbicide resistance practices increase rate of soybean canopy coverage. The group worked with six other universities at eight field locations across the Midwest. Researchers used a digital-image technology called SigmaScan to measure the amount of canopy coverage through color identification.
“We took pictures of soybean fields and SigmaScan detected the percentage of green pixels in the images – telling us the approximate canopy coverage of the area,” Butts stated. “We’re investigating how different herbicide resistance strategies, row width and other factors contribute to a field’s overall canopy coverage and yield.”
Researchers began collecting data during the 2013 growing season and continue to add to that data this year. Though not the intent of the project, Butts indicated the SigmaScan technology could be used by farmers and grain elevators in the future.
The project also includes researchers from the University of Arkansas, University of Nebraska-Lincoln, Southern Illinois University, University of Tennessee and The Ohio State University. Purdue University and University of Missouri joined the partnership in 2014.