• Agronomic Insights
  • Sep 08, 2021

Why Fall Burndown Beats Spring Weed Control

Sprayer on a recently harvested field.
As farmers in the Northern Plains know all too well, relying on fall tillage to break up weed pressure going into the winter comes with some risk, especially if you end up not working the fields. When dry field conditions force producers to leave fields with bare stubble to conserve moisture, they can face heightened weed pressure in the spring.
 
That’s why I always encourage making a burndown application in the fall when weeds are easiest to control. This incredibly important for those who practice minimum/no-till and have a history of winter annuals.
 
So, why do some producers shy away from making a fall burndown application? If I had to guess, I’d say most don’t want the added cost. This application comes at a time when farmers have finally recouped input costs from their spring crop, and they’re looking at purchasing seed for next year. I understand this hesitation, but the weeds don’t care.

Fall Burndown Provides Efficacy at a Low Cost

The good news is that a fall burndown application doesn’t need to be complicated or expensive to be effective. In fact, even a late fall burndown made shortly before freezing is likely to provide far better results than a spring herbicide tank mix at a fraction of the cost.
 
Provided you’re planting a herbicide-resistant crop next spring, all you need to include in your burndown application this fall is glyphosate, a growth regulator like 2,4-D or dicamba to target glyphosate-resistant weeds and the appropriate adjuvant package. I usually recommend a tank mix containing the following products to my customers:
  • WinField® United Cornerstone® 5 Plus herbicide (glyphosate).
  • WinField United Shredder® E-99 herbicide (2,4-D).
  • WinField United Class Act® NG® adjuvant, which contains a quality nonionic surfactant.
  • WinField United InterLock® adjuvant to lock in spray coverage and lock out drift. 
For an average cost in the neighborhood of $5-$6 per acre1, this application can wipe out most weed concerns leading up to winter and help prevent them from returning early next spring. Just be sure to consult your local WinField United retailer for assistance in determining the best product rates for your fields.

Is Residual Chemistry Needed?

If you’re planting a herbicide-tolerant crop next season, it isn’t necessary to include a residual herbicide in your fall burndown application unless you’re dealing with a complex weed issue. In most cases, you can just come back next spring and clean up newly sprouted weeds with the appropriate postemergent herbicide application.
 
But if you’re planting a conventional crop, wheat on no-till or minimum-till acres, or pulse crops like peas, lentils, chickpeas or dry edible beans, it’s best to include a fall residual product in your burndown tank mix. An effective flumioxazin option like Valor® herbicide applied in the fall will continue to suppress marestail, narrowleaf hawksbeard and downy brome in the spring.

The Downsides of Relying on a Spring Application

Wheat producers who practice minimum/no-till and skip a burndown application this fall will be forced to deal with broadleaf weeds and downy brome next spring. Pyroxsulam products like OpenSky® and GoldSky® herbicides are the best options for controlling downy brome on wheat and other cereal crops. Everest® 3.0 herbicide also offers residual control, but it isn’t used as often as the others due to its longer rotational restrictions.
 
Whichever of these products you choose, relying on it for your spring herbicide application will cost about $25 per acre1. For that amount, you’d hope to get excellent control, but these tank mixes are not a silver bullet by any means. Since weeds that started growing in fall are larger and harder to manage come spring, farmers are often disappointed by the modest results they attain.
 
Choosing between spending $5-$6 per acre this fall to achieve effective control, or $25 per acre next spring to get mediocre results is a no-brainer. Depending on the size of your operation, you can save thousands of dollars with a fall burndown application, all while receiving better results.

Timing is Important, But Not an End All

The best time to make your fall burndown application is when weeds germinate after harvest, which is generally mid-September in the Northern Plains. But, as I implied earlier, you can still achieve adequate control as long as you apply a fall burndown before the first heavy freeze, or even post freeze if growing temperatures return for an extended amount of time before winter ultimately arrives.
 
I got a firsthand look at what a late application can do last fall when I made a burndown application on some volunteer wheat in a local grower’s field. As it turned out, it snowed the next day and didn’t end up melting off until spring. I thought that application was going to be a lost cause, so imagine my surprise when I saw excellent results in the spring. In addition to eliminating the volunteer wheat, there were perfect strips of black soil where we sprayed, but carpets of cheatgrass had started growing in the unsprayed border areas.
 
If you’re tired of large weeds and winter grasses outlasting your spring herbicide treatment and reducing your yield potential, give some serious thought to making a burndown application this fall. Your local WinField United retailer will help custom-tailor the right tank mix for your operation.
 
1Per acre herbicide application costs are supplied only as an estimate and will vary depending upon current pricing and rates used.
 
All photos are either the property of WinField United or used with permission.

© 2021 WinField United. Important: Before use always read and follow label instructions. Crop performance is dependent on several factors many of which are beyond the control of WinField United, including without limitation, soil type, pest pressures, agronomic practices and weather conditions. Growers are encouraged to consider data from multiple locations, over multiple years and to be mindful of how such agronomic conditions could impact results. Class Act®, Cornerstone®, InterLock®, NG®, Shredder® and WinField® are trademarks of WinField United. Valor® is a registered trademark of Valent U.S.A. Corporation. OpenSky® and GoldSky® are trademarks of Dow AgroSciences, DuPont or Pioneer and their affiliated companies or respective owners. Everest® is a registered trademark of Arysta LifeScience North America, LLC.



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