Strategies are Limited for Late Season Marestail Control in Soybeans
University of Illinois’ Aaron Hager wrote an excellent article on Late-Season Herbicide Applications in Soybean. Many farmers are struggling with weeds such as volunteer corn, velvetleaf, etc. Most of these weeds are easy enough to control but there are a couple of weeds that are very difficult to control. One of those weeds that is making its presence known in Ohio is marestail.
Unfortunately, there are not many great options for postemergence control of marestail. In populations that are not glyphosate- or ALS-resistant, postemergence application of glyphosate, FirstRate, or Classic can control small plants that emerge after soybean planting. A combination of glyphosate plus either Classic or FirstRate has the most chance for success, but primarily for control of plants that emerged after soybean planting and are still small. Postemergence application of Ignite in Liberty Link soybeans can control small plants.
Below is a factsheet from Purdue/OSU on marestail control; you’ll note the information is heavily geared to preplant/preemergence control.