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The true cost of weed control

Navigating weed control amidst soybean herbicide technology consolidation.

February 1, 2024

4 Min Read
Soybean traits - What have we learned?
Submitted by Beck's Hybrids.

The last several years have brought about significant soybean herbicide technology consolidation. This rapid merging of herbicide resistance traits into single soybean cultivars would make it seem as if weed control has been simplified. However, as the stacking of herbicide resistance traits has taken place, the pressure on specific Sites of Action (SOA) has increased exponentially. Preservation of Enlist E3®, XtendFlex®, and future stacked soybean traits is heavily predicated on not only sound management practices but also the responsible use of residual herbicides as well.

WEED COMPETITION: THE NOT-SO-OBVIOUS, MORE SIGNIFICANT IMPACT

Weeds directly impact crop yields by competing for resources like water, sunlight, and nutrients. However, there are more impactful means by which weeds rob yield. Recently, researchers discovered that plants experience stress just by “seeing” weeds or unlike plants. The University of Guelph uncovered that reflected far-red light from weeds is actually more damming to crop yield than competition for the resources previously listed.

This new discovery emphasizes the importance of two things:

1. Pre-Emergence: Utilize a residual herbicide program effective on your specific weed spectrum at rates appropriate for your weed density and utilize multiple effective SOAs. While less comprehensive programs will save you money up-front, weed escapes result in reflected light that may likely cost you more in the end. Researchers also discovered that competition throughout early growth stages resulted in a greater yield impact than competition later in the growing season.

Figure 1 indicates the importance of multiple SOAs to waterhemp control. The same principle applies to other troublesome weeds like giant ragweed, kochia, palmer amaranth, and marestail.

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2. Post-Emergence: Timeliness is not only key to controlling existing weeds while they are smaller and manageable, but the economic impact of delayed weed control is also now known. According to the University of Nebraska, every growth stage of delayed weed control in soybeans equates to 2.5% yield loss (Figure 2).

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SOYBEAN TRAITS - WHAT HAVE WE LEARNED?

Enlist E3®

  • Enlist® herbicides: work most effectively with 2 to 3 lb./A. of AMS

  • Post-emergence waterhemp control: Enlist One® + Liberty® (92%) is more effective than Enlist One + glyphosate (85%)

  • Carrier Rate: Enlist One + glyphosate at 15 gal./A. = an increase of 17% to 20% weed control vs. Enlist One + glyphosate at 10 gal./A.

  • Enlist One + Clethodim: antagonism can occur, so increase the clethodim rate by 33% or greater for effective grass control

  • Enlist One + Liberty: tank-mix at a 1:1 ratio

  • Enlist One + Liberty: offers two effective SOAs on glyphosate-resistant weeds

  • Post-emergence cutoff: through R1. Expect soybeans to "droop" very soon following a post-emergence application. Recovery will occur within days.

XtendFlex®

  • Engenia®/XtendiMax® = improved marestail burndown vs. Enlist herbicides

  • Engenia/XtendiMax = significant soil activity compared to Enlist herbicides

  • Dicamba (DGA salt) = 50% less volatility applied to soil vs. foliage (Iowa State University)

  • Engenia/XtendiMax: cannot be tank-mixed with Liberty

  • Post-emergence cutoff: through June 30. Applications after R1 are prohibited (dates vary by state.)

Liberty® + Glyphosate

  • AMS: 2 to 3 lb./A. will result in the most effective control

  • Manage like Liberty on its own:

  • Tank-mix: 1.125 lb. i.e. glyphosate to every 32 oz. of Liberty

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While the stacking of herbicide traits affords us many conveniences, the key to maximizing ROI and sustaining these technologies is to do all we can to prevent weeds from ever emerging in the first place.

Beck's - Farmers At Heart® - revolutionized the customer seed buying experience by remaining true to a foundation built on faith, family, and farming. Founded in 1937, Beck's appreciates the farmers who have helped them become the largest family-owned retail seed company and the third-largest seed brand in the United States. The Beck family is now in its fifth generation of family members who work in the business to honor God and help farmers succeed. The Beck family and team of employees help farmers achieve success from generation to generation through authentic customer experiences, product diversity, seed quality, and performance. With a home office located in Atlanta, Ind., Beck's serves farmers throughout the Midwest and Mid-South. For more information about Beck's Superior Hybrids, Inc., visit www.beckshybrids.com.

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