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Understanding the Differences in Group 15 Herbicides

December 19, 2022
weeds growing in an untreated field

Weeds growing in an untreated plot at the Shallowater, TX, Grow More™ Experience site

Falling into a familiar routine is easy, but when it comes to weed resistance, that can be a costly recipe for disaster. Resistant weeds require diversified herbicide chemistries with multiple active ingredients and effective sites of action. This ensures you’re attacking weeds from multiple angles and helps preserve the long-term efficacy of the active ingredients. Taking time between seasons to examine the strengths and weaknesses of your current weed management program could be what stands between your fields and increased yield potential.

While choosing herbicides with multiple active ingredients and different sites of action is important, something we can overlook is half-life of a herbicide and the role it plays in length of residual control. The half-life of a herbicide describes the length of time it takes for 50% of the herbicide to break down and no longer be effective.

Syngenta Agronomy Service Representative Brent Besler shares how this ability to stay in the soil later into the season can have a major impact on the efficacy of different Group 15 herbicides:

Besler identifies a few key takeaways about the differences between Syngenta and other Group 15 herbicides on the market as he walks through a bare-ground trial at the Shallowater, TX, Grow More Experience site:

  • Dual Magnum® herbicide:
    • Half-life: 48 days
    • Benefits: While an activating rain is required for any herbicide application, Dual Magnum typically only requires 0.5” of rainfall for activation, which is especially valuable in areas with limited rainfall. Dual Magnum also offers longer soil residual activity on annual grass and small-seeded broadleaf weeds.
  • Outlook® herbicide:
    • Half-life: 29 days
    • Drawbacks: This herbicide can activate quickly but can also move out of the rooting zone quickly, so you could lose control of tough weeds like Palmer amaranth that typically germinate in the top inch or so of soil.
  • Warrant® herbicide:
    • Half-life: 16 days
    • Drawbacks: This herbicide not only has a short half-life, but it’s also encapsulated, which delays the release of the active ingredient. Both factors contribute to a short window of efficacy, which can lead to missed weed control in the top inch of soil.

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Syngenta hereby disclaims any liability for third party websites referenced herein.

Performance assessments are based upon results or analysis of public information, field observations and/or internal Syngenta evaluations. Trials reflect treatment rates commonly recommended in the marketplace.

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