Corn and Soybean Herbicide Trials Show How to Combat Waterhemp
A large patch of waterhemp at the edge of the Pontiac, IL, Grow MoreTM Experience site.
Waterhemp is the most problematic weed at the Pontiac, IL, Grow More Experience site due to its long-standing presence in the area, massive seed production and resistance to many different sites of action (SOAs). It’s followed by Palmer amaranth, a relative newcomer to the area, and giant ragweed. All 3 weeds are very different but, if left unchecked, can seriously reduce yield potential by competing with corn and soybeans for valuable resources like nitrogen, sunlight and water throughout the season.
So what’s the best way to control these and other tough weeds? A sound and reliable agronomic strategy is to use herbicides with multiple effective SOAs and overlapping residuals at their full labeled rates. Additionally, this strategy can be combined with other agronomic tools, like cover crops or tillage, for enhanced weed management and resistance prevention.
To show the importance of using herbicides with multiple effective SOAs, we set up several herbicide trials – corn and soybean bare ground trials and an in-crop soybean trial. The trial plots were set up on May 13, and each preemergence herbicide application received an activating rainfall shortly after. Since then, conditions have been on the drier side with some sporadic rain in between.
Watch as Agronomic Service Representative Kevin Scholl talks through the trials, or check out a few pictures below:
Corn herbicide bare-ground trial:
Acuron® corn herbicide applied preemergence at the full labeled rate (3 qt/A). Acuron contains 4 active ingredients and 3 effective SOAs (Groups 5, 15 and 27). Photo taken 56 days after treatment.
Soybean herbicide in-crop trial:
Boundary® 6.5 EC herbicide applied preemergence at the full labeled rate (2 pt/A) followed by a post-emergence treatment of Flexstar® GT 3.5 herbicide (3.5 pt/A) plus Dual II Magnum® herbicide (1 pt/A) and Enlist One® (2 pt/A). This program includes 5 total SOAs (Groups 4, 5, 9, 14, 15). Photo taken 56 days after preemergence treatment.
Boundary 6.5 EC herbicide applied preemergence at the full labeled rate (2 pt/A) followed by a post-emergence treatment of Prefix® herbicide (2 pt/A) plus Liberty® 280 SL herbicide (36 fl oz/A). This program includes 4 total SOAs (Groups 5, 10, 14 and 15). Photo taken 56 days after preemergence treatment.
Boundary 6.5 EC herbicide applied preemergence at the full labeled rate (2 pt/A) followed by a post-emergence treatment of Tavium® Plus VaporGrip® Technology herbicide (3.53 pt/A) plus glyphosate (26 fl oz/A). This program includes 4 total SOAs (Groups 4, 5, 9 and 15). Photo taken 56 days after preemergence treatment.
To start and stay clean in 2021, we recommend Acuron herbicide or it’s atrazine-free counterpart, Acuron Flexi, in corn. Acuron and Acuron Flexi both contain the Syngenta-exclusive active ingredient, bicyclopyrone, and Acuron is the only corn herbicide that delivers 5-15 more bushels an acre when used preemergence at the full labeled rate.* In a 2-pass program, a foundation rate of Acuron or Acuron Flexi can be followed by the remaining rate post-emergence or an application of Halex® GT plus either an atrazine or dicamba for an additional SOA. Calculate the extra revenue potential you could find next season with Acuron.
In soybeans, we recommend a preemergence application of Boundary 6.5 EC herbicide, which works well with a variety of soybean trait systems, including Roundup Ready 2 Xtend® Soybeans, Enlist™ and LibertyLink® Soybeans. For the post-emergence application, we recommend Flexstar GT 3.5 or Prefix herbicides. Tavium Plus VaporGrip Technology herbicide is also a post-emergence option in dicamba-tolerant soybeans. All of these programs include multiple, effective SOAs for control of tough weeds through canopy or beyond.
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*Acuron yield advantage range based on 2016 Syngenta and university trials comparing Acuron to Corvus®, Resicore®, SureStart® II and Verdict® applied preemergence at full label rates.