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Overlapping Residuals Protect Future Soybean Crops

February 12, 2021
This agronomic image shows waterhemp


Maintaining effective weed management throughout the season sets soybean fields up for success now and in the years to come. The best way for growers to achieve optimal management, protect yield and reduce their weed seed bank is with an overlapping residual herbicide program.

The video below, recorded at our Orient, IA, Grow More™ Experience site in 2020, illustrates the importance of overlapping residual weed control. Dean Grossnickle, Syngenta agronomy service representative, explains how easily a single waterhemp plant can go to seed and wreak havoc on a field if it’s not well managed through the season. But waterhemp isn’t the only weed that can quickly flood the weed seed bank and create years of problems:

The Impact of Problem Weeds

  • Marestail produces up to 200,000 seeds per plant. These seeds are highly mobile, which result in rapid spread.
  • Palmer amaranth produces 10,000 to 100,000 seeds per plant. It has a faster and more competitive growth rate than other pigweed species and can grow up to 3” per day, quickly overtaking crops.
  • Giant ragweed can produce up to 5,100 seeds per plant. It has an initial competitive advantage over many other crops and weeds due to its early emergence and rapid growth rate.
  • Morningglory can produce up to 500 seeds per plant. These seeds have a hard protective coating that allows them to remain viable in the soil for up to 50 years.

Pressure from these weeds goes beyond creating management headaches – it has a major impact on yield. For instance, research shows that it only takes season-long competition from 2 giant ragweed plants per 110 sq. feet to reduce yields by 13%. With a few escaped weeds able to create significant yield loss, there’s no point during the season when growers can let their guard down.

As Grossnickle explains in the video, a planned 2-pass program that uses robust preemergence and post-emergence herbicides is the best strategy to manage weeds through the season and prevent additions to the weed seed bank.

We recommend a preemergence application of Boundary® 6.5 EC, BroadAxe® XC or Prefix® herbicides followed by Tavium® Plus VaporGrip® Technology herbicide in dicamba-tolerant soybeans for a 2-pass system with both contact and residual control. Tavium, the market’s first and only premix residual dicamba herbicide, manages a broad spectrum of tough weeds for up to 3 weeks longer than dicamba alone.

To find the right herbicide for your field, view the soybean herbicide program planning tool.

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