Soybean Herbicide Choice Critical to Managing Weeds
Agronomic Service Representative Dean Grossnickle compares 2 soybean herbicide treatments at a recent Grow More™ Experience event in Slater, IA.
Conditions at the start of the 2019 season were not favorable for many growers. They were, however, advantageous for early-season weeds. Delayed fieldwork, late planting, excessive rainfall and cool conditions, combined with herbicide resistance, meant countless tough weeds emerged safely and then grew past the optimal herbicide application height of less than 4”. Many of those tough weeds remained uncontrolled and went to seed, adding to the weed seed bank for 2020 and the likelihood that fields have increased pressure next season.
The soybean herbicide trials at our Slater, IA, Grow MoreTM Experience and Gilbert, IA, research and development sites highlighted performance in this season’s less-than-ideal conditions. Here’s what we saw at each site:
- Soybeans planted June 3.
- Preemergence herbicide applications made on June 3 and post-emergence applications made on June 25.
- Driver weeds include: giant foxtail, morningglory, redroot pigweed, waterhemp and velvetleaf.
Untreated check full of the aforementioned driver weeds.
Prefix® herbicide plus Tricor® applied preemergence, followed by Tavium plus glyphosate. 49 days after second treatment.
- Soybeans planted April 15.
- Preemergence herbicide applications made on April 15 and post-emergence applications made on June 10.
- Driver weeds include: giant foxtail, common lambsquarters, purslane, smartweed, waterhemp and velvetleaf.
Boundary 6.5 EC applied preemergence, followed by Tavium and glyphosate. 64 days after second treatment.
Valor® SX applied preemergence, followed by XtendiMax® and glyphosate. 64 days after second treatment.
To start clean and stay clean in 2020 and manage increased weed pressure, our best recommendation is a burndown application of Gramoxone® SL 2.0 herbicide followed by:
- A preemergence application of Boundary 6.5 EC or BroadAxe® XC herbicides, both of which contain 2 effective SOAs. Those can be followed by Tavium herbicide, the market’s first premix residual dicamba herbicide. Tavium is a formulation of dicamba and S-metolachlor, making it convenient for managing key ALS-, PPO- and glyphosate-resistant broadleaf and grass weeds.
- Keep in mind that better weed control can lead to better yield potential.
- In addition to higher potential yields, clean fields lead to cleaner grain and less chance of being docked at the elevator for weed seed.
Interested to know how the corn herbicides performed in Slater, IA? Check out the corn herbicide version of this post.
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Performance assessments are based upon results or analysis of public information, field observations and/or internal Syngenta evaluations.
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