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The War Against Giant Ragweed Continues Until Harvest

August 31, 2019
This agronomic image shows giant ragweed

Giant ragweed competes with corn in DeKalb, IL.

Giant ragweed in corn and soybean fields is not a rare site as you drive past Midwest farm fields. This large-seeded broadleaf weed can grow up to 20’ tall and consume large amounts of vital in-field resources like water, sunlight and nitrogen that impact corn and soybean health. A single giant ragweed plant consumes nearly 3x as much water to produce 1 lb. of dry matter as a corn plant, meaning these weeds are problematic yield robbers even in small populations.

Similar to other large-seeded broadleaf weeds, giant ragweed is difficult to control because its seeds germinate deep within the soil profile, where they are shielded from herbicide applications. This deeper germination depth means that giant ragweed emerges with more plant mass, making it even harder to control with post-emergence herbicide applications.

At our DeKalb, IL, Grow More™ Experience site, we have trials evaluating different herbicides sites of action (SOAs). This year we saw especially heavy weed pressure because of the herbicide application delays caused by the prolonged rains during the spring. In our corn herbicide bare ground SOAs trial pictured here, we’re able to show the difference between components of Acuron® corn herbicide versus competitors and how they attack giant ragweed.

Active ingredient of Resicore: Stinger® 5.07 fl oz/A with SOA 4

Active ingredient of Resicore® : Stinger® 5.07 fl oz/A with SOA 4.

Active ingredients of Acuron: Callisto® 5.76 fl oz/A + BIR 3.5 fl oz/A + AAtrex® 4L 0.75 qt/A with SOA 5+27

Active ingredients of Acuron: Callisto® 5.76 fl oz/A + BIR 3.5 fl oz/A + AAtrex® 4L 0.75 qt/A with SOA 5+27.

To combat giant ragweed in corn, we recommend using a 2-pass system of Acuron or Acuron® Flexi herbicide followed by Halex® GT herbicide plus an atrazine brand. Each of these corn herbicide premixes contain multiple, effective SOAs for built-in resistance management and provides long-lasting residual control, especially when used in a 2-pass system. And, Acuron gives you 5-15 more bushels an acre than any other herbicide*.

Contact your Syngenta sales representative for help identifying the right weed management plan for your area.

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All photos are either the property of Syngenta or are used with permission.

©2019 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.

*Yield advantage range based on 2016 Syngenta and University trials comparing Acuron to Corvus®, Resicore, SureStart® II and Verdict®.