Fall Herbicide Considerations

Since harvest is nearing completion or has been completed, thoughts are turning to what corn and soybean products worked well this year and which ones should be planted for the 2022 growing season. Another important decision to make is if a fall herbicide program is needed and what should be used. 

As harvest winds down, it is important to scout fields for weed pressure, density, and the species present. Type of tillage and crop rotation also needs to be determined. 

Most farmers are aware of troublesome fields that often have winter annuals like marestail, henbit, and pennycress. Those fields should be scouted early and often. With the wet springs that some farmers have experienced the last few years, getting timely herbicide applications completed in the spring can be difficult. Therefore, getting ahead of winter annuals in the fall can help take the pressure off getting timely spring-time applications completed. While a fall applied herbicide program is not intended to provide weed control into the next summer, they can be very beneficial when trying to start clean, especially in no till situations. 

Fall Timing 

Timing on a fall herbicide program is important. For the most part, in Illinois, any time before Thanksgiving is optimal and depending on the weather, we can sometimes even push a bit later. Always read and follow the label directions on carrier type, volume, and conditions for application. In general, for burndown programs, good sunshine with daytime temperatures above the mid-50s and nighttime temperatures in the 40s or above can give better control than applications made on colder, overcast days. With residual programs, the target should be soil temperatures between the upper 30s and 50° F.

Residue Management 

Generally, the presence of crop residue can be managed. The herbicides seem to work well even with heavy crop residue. When running a burndown only program, it’s a good idea to wait a bit after harvest to give the weeds time to emerge through the residue but not so long that the temperatures drop off. If planning to use a residual, then pushing toward the later side may not be as much of an issue and the cooler soil temperatures can help hold onto the residual longer. The ground should not be frozen because of runoff risk. 

Spring Timing

One of the great things about a fall herbicide program is that it can give us clean fields early in the spring. Take advantage of those clean fields and get that crop in early. We often see an advantage for planting soybean fields early and an early canopy helps manage weed growth. 

Whether using a burndown only fall program or a fall program that includes a residual like Autumn™ Super 51 WDG herbicide, a fall weed control program can be a great tool for farmers to start clean. Additionally, clean fields can allow soils to warm quicker, reduce the attractiveness of the fields to black cutworm moths, and make them less likely to support nematodes, white grubs, and wireworms. 

Brandon Beck

Technical Agronomist

Legal Statement

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.

Not all products are registered 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. Channel® and the Arrow Design® and Seedsmanship At Work® are registered trademarks of Channel Bio, LLC. Autumn™ is a trademark 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. ©2021 Bayer Group. All rights reserved.

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