3 Tips for Applying Herbicide to Soybeans

Matt Moore

Matt Moore, Soybean Product Manager

Weeds, when left unmanaged, can quickly takeover a field and greatly reduce yield.

Planting into weed-free fields and using pre-plant and pre-emergence herbicides with residual gets your crop off to a clean start. Using a pre-emergence herbicide also can provide a wider window to make your post-emergence herbicide application.

Below are three basic steps to take when applying herbicide to soybeans:

  1. The post application, regardless of what herbicide platform is used, should target small weeds of three inches or less. Pair it with a residual to provide weed control through canopy closure.
  2. Optimize coverage by using the correct rate, water volume, and spray droplet size, according to the label.
  3. Continue to monitor soybean fields throughout the growing season. If a weed escape occurs, a second post-application may be necessary.

Slow the Growth of Weed Resistance

It’s important to consider the number of effective modes of action in each herbicide application. Research by Dr. Aaron Hager of the University of Illinois and other weed scientists shows the significant benefits of using multiple modes of action (MOA). Their research examined factors related to landscape, weed, and management from 105 Illinois grain fields, including over 500 site-years of herbicide application records.

Their research shows that management practices are the best predictors of glyphosate-resistant waterhemp among all 66 variables included in the analysis. The occurrence of glyphosate-resistant waterhemp was greatest in fields where glyphosate had been used in more than 75% of the seasons included in the analysis, where fewer MOA were used each year, and where herbicide rotation occurred annually. However, exposing populations to multiple MOA through tank-mixtures greatly reduced the selection for glyphosate-resistant waterhemp.

A field in which 2.5 MOA per application were used was 83 times less likely to select glyphosate-resistant waterhemp within four to six years than a field in which only 1.5 MOA per application were used. Researchers stressed this strategy only works if each component of the tank-mixture is effective against the target species.  They also emphasized that effective, long-term weed management will require even more diverse management practices.

Weed Resistance

2022 Dicamba Application Updates 

For the 2022 Season, the revised federal labels for XtendiMax®, Engenia®, and Tavium® will contain the following prohibitions:

  • No spraying on dicamba-tolerant (DT) crops after June 20 in Iowa.
  • No spraying on DT crops after June 12 in Minnesota, south of Interstate 94.
  • No spraying on DT crops after June 30 in Minnesota, north of Interstate 94.
  • No spraying when the forecast for high temperature exceeds 85 degrees Fahrenheit in Minnesota.