3 corn fields

Two-pass versus one-pass weed control programs in corn

May 18, 2023 8:00 a.m.

Weed management strategies have changed significantly as farmers are facing the challenge of herbicide resistance. Successful weed management strategies use an integrated approach of incorporating herbicide, mechanical, and cultural control tactics. As a component of herbicide management, the use of residual herbicides and different sites of action have become the cornerstones of successful sustainable herbicide programs. In most cases, these tactics are used in a two-pass herbicide scheme. Recent crop profit margins, however, are causing many farmers to re-evaluate many inputs including herbicide costs. Thus, many are considering a one-pass scheme, particularly if they are not dealing with herbicide-resistant weed populations, using conventional tillage, and planting a glyphosate-tolerant corn product.

Advantages of a Two-Pass Scheme

Field trials conducted over a three-year period compared variations in herbicide application schemes in a two-pass system in a glyphosate-tolerant corn product. A preemergence residual herbicide application followed by a late post application of glyphosate provided full-season weed control and was equal in yield to a weed-free plot. Additionally, the most effective and profitable weed management strategies included 2, two-pass systems: a sequential application of glyphosate and a preemergence residual herbicide and a late application of glyphosate. Additionally, the two-pass program that included a residual product had glyphosate stewardship benefits.1

Can a One-Pass Scheme Work?

While the benefit of a one-pass program is the reduced costs for that production year, there is a higher risk of failure and, because of the possibility of reduced control, a possibility for a build-up in the weed seed bank for the following years. A successful one-pass program must include a herbicide or herbicide tank mix that can provide excellent control across a wide spectrum of weeds and control weeds until row closure that allows the canopy to shade the weeds, limiting their growth. Dry conditions after application of a one-pass preemergence herbicide program often lead to poor performance. A rule of thumb is that at least a half inch of water is needed to move the herbicide to the necessary depth to provide control of germinating weed seeds.

One Product for Both Options

TriVolt™ herbicide from Bayer brings built-in resistance management and consistently high levels of weed control for corn growers. This proprietary combination of Groups 2, 15, and 27 herbicides provides burndown and residual activity for up to 8 weeks through a variety of weather conditions. Following a dry period, Isoxaflutole re-activates with as little as ½ inch of rain and provides continued residual activity. When tank-mixed with Atrazine, TriVolt™ delivers 4 different sites of action to help combat troublesome grass and broadleaf weeds, such as Waterhemp and Palmer Amaranth.

To see how farmers utilized TriVolt herbicide in one and two-pass schemes, visit trivoltinaction.com

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1Soltani, N., Nurse, R.E., Gillar, C.L., and Sikkema, P.H. 2013. Weed control, environmental impact and profitability of two-pass weed management strategies in glyphosate-resistant corn. The Open Plant Science Journal. 7:31-38. https:// benthamopen.com/contents/pdf/TOPSJ/TOPSJ-7-31.pdf

Legal Statements

ALWAYS READ AND FOLLOW PESTICIDE LABEL DIRECTIONS. Performance may vary, from location to location and from year to year, as local growing, soil and weather conditions may vary. Growers should evaluate data from multiple locations and years whenever possible and should consider the impacts of these conditions on the grower’s fields.

TriVolt™ is a restricted use pesticide. Not all products are registered for use in all states and may be subject to use restrictions. The distribution, sale, or use of an unregistered pesticide is a violation of federal and/or state law and is strictly prohibited. Check with your local dealer or representative for the product registration status in your state. Tank mixtures: The applicable labeling for each product must be in the possession of the user at the time of application. Follow applicable use instructions, including application rates, precautions and restrictions of each product used in the tank mixture. Not all tank mix product formulations have been tested for compatibility or performance other than specifically listed by brand name. Always predetermine the compatibility of tank mixtures by mixing small proportional quantities in advance. Harness®, Laudis® , Roundup PowerMAX® and TriVolt™ are trademarks of Bayer Group. All other trademarks are the property of their respective owners. For additional product information call toll-free 1-866-99-BAYER (1-866-992-2937) or visit our website at www.BayerCropScience.us. Bayer CropScience LP, 800 North Lindbergh Boulevard, St. Louis, MO 63167. ©2023 Bayer Group. All rights reserved.