December 13, 2019
Glyphosate-resistant weeds continue to be a concern across corn and soybean growing areas. The wet spring and early summer that many growers faced in the Midwest made it challenging to make timely herbicide applications. Lack of weed control this past year is likely to lead to an increase in the weed seed bank, including glyphosate-resistant weeds.
If a glyphosate application was made and weed escapes occurred, there are several factors to consider. The escapes could be the result of an incorrect application rate for the weed size or species, rain before the glyphosate was absorbed by the weed, weather-stressed weeds, incomplete spray coverage, or weeds emerging after the glyphosate application rather than glyphosate resistance. If lack of weed control cannot be explained by the environment or these application factors, glyphosate resistance may be a concern, especially if the weed escapes were Palmer amaranth, waterhemp or marestail.
Looking ahead to the next growing season, it is important to have a plan in place if you suspect your fields may contain glyphosate-resistant weeds. Below are some things to keep in mind when dealing with glyphosate resistance.
- Start with clean fields by utilizing a pre-emergence residual herbicide.
- Add a residual chemistry to the postemergence application so that residuals overlap.
- Implement an herbicide program that employs multiple sites of action.
- Apply glyphosate at the labeled rate and at the correct weed heights.
- Utilize cultivation or other mechanical weed management practices.
- Keep field edges clean.
If you have any additional questions about managing glyphosate-resistant weeds, please reach out to your local Channel Seedsman or technical agronomist.
Sources:
Boerboom, C. (University of Wisconsin) and Owen, M. (Iowa State University) 2006. Facts about glyphosate resistant weeds. The Glyphosate, Weeds, and Crops Series. GWC-1. Knowledge to Go. Purdue Extension. Purdue University. https://www.extension.purdue.edu/extmedia/gwc/gwc-1.pdf
Web source verified 10/15/19.
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. 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. Channel® and the Arrow Design® and Seedsmanship At Work® are registered trademarks of Channel Bio, LLC. All other trademarks are the property of their respective owners. ©2019 Bayer Group. All rights reserved.