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It’s Never Too Early to Scout for Corn and Soybean Weeds

June 11, 2020
This agronomic image shows field scouting

Early-season weeds are competitive and can reduce your crop’s yield potential right from the start. Marestail, giant ragweed and common lambsquarters can emerge as early as March, so it’s important to be proactive early in the season.

As you develop your weed management program, devote some time to scouting your fields, both early and often. Knowing the type, volume and location of weeds will be valuable information for protecting your yield potential throughout the year. Scouting can also help you determine the most cost-effective options available to fight pest pressure and resistance.

Top 6 Tips to Help You Scout

This chart shows walking patterns for field scouting

Follow an M-shaped walking pattern to get the best representation of weed pressure across the whole field.

  1. According to the University of Wisconsin-Extension, your walking route is the foundation for effective scouting. For square and rectangular fields, an M-shaped pattern will be the most beneficial. For irregular shapes, ensure you cover a representative amount of the field.
  2. Keep in mind that you can’t judge the weed population of an entire field by what you see on the edges.
  3. For larger fields, you will likely need to split the area into smaller parts. This helps ensure you have the most accurate results, even if population data differs from one section of the field to another. Note the weed species you see, their locations in the field and the degree of control achieved with your current program and past herbicides.
  4. Weed populations can be split into 4 categories, which can help determine your control options:
    • Scattered – Occurs when there are not enough weeds to cause yield loss, but the population will produce seed and can increase the weed seed bank if left uncontrolled.
    • Slight – In this case, yield loss is unlikely but possible in areas where pressure is heavier. The population is considered slight when there is 1 weed in every 3 feet of row.
    • Moderate – At this point, yield loss is likely unless an effective management program is used. Moderate pressure is an average of 1 weed per foot of row. You may also see spots with severe populations.
    • Severe – With this level of weed pressure, yield loss will undoubtedly occur unless effective control strategies are utilized. For broadleaf species, more than 1 weed per foot of row constitutes severe pressure. For grass weeds, it’s 3 plants per foot of row.
  5. Use your findings to determine which weed control measures are right for your fields, both this season and next.
  6. Scout early and often. Then use that information to plan your weed management program accordingly.

In soybeans, 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 premix residual dicamba herbicide, controls a broad spectrum of tough weeds for up to 3 weeks longer than dicamba alone.

For corn, Acuron® herbicide delivers 5-15 more bushels an acre when used preemergence at full label rates by controlling the tough weeds that other products miss.* Acuron has unmatched application flexibility, from 28 days preplant up to 12” corn. It can be followed up with a post-emergence herbicide, such as Halex® GT. This approach also helps with weed resistance management, as it gives 4 total sites of action in fields. Calculate the potential extra revenue you could be making with Acuron.

See how weed resistance has spread across the U.S. in the last 50 years, and learn more about how to keep tough weeds from jeopardizing your profits.

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©2020 Syngenta. The trademarks or service marks displayed or otherwise used herein are the property of a Syngenta Group Company. All other trademarks are the property of their respective owners.

* When applied preemergence and at full label rates. Acuron yield advantage range based on 2016 Syngenta and University trials comparing Acuron to Corvus®, Resicore®, SureStart® II and Verdict®. For more information on Acuron versus an individual product, ask your Syngenta representative.

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