There are many reasons a corn crop may fail. In some years it’s a late frost and in others, soil surface crusting. Regardless of the reason the stand fails, it is important to destroy the original crop before replanting. Yield losses can occur if just 5,000 of the original corn plants remain to compete with the new stand. Therefore, it is imperative to successfully eradicate as much of the existing stand as possible.

Tillage is an effective way to control a failed stand of corn. However, the implement used must be aggressive and run perpendicular to the planted row. Typically, it will take more than one pass across the field to successfully uproot the original stand. Because the growing point on corn is located below ground until the plant reaches the V6 growth stage, it’s important to completely excavate the entire plant from the ground. In some situations, the soil is highly erodible and tillage is not an option. In cases such as these, herbicides may be the only option.

When it comes to chemical control, it is important to know the herbicide resistance traits of the failed stand. If the corn in question is Non-GMO or conventional, then glyphosate (Roundup PowerMAX®) would be the best option, but clethodim (Select Max®), paraquat with metribuzin (Gramoxone® with Sencor®), or glufosinate (Liberty®) could also be used. If Select Max is used, there is a mandatory waiting period before replanting corn. Some corn varieties on the market have a tolerance to glyphosate, but not Liberty. In these cases, Liberty can be used at a rate of 32 to 34 oz./A. to control small (V1 to V3) corn.

If the failed stand of corn is stacked with tolerance to both Glyphosate and Liberty, then the best options left are 48 oz. of Gramoxone with 4 oz. of Sencor or 6 oz. of Select Max. The Select Max label indicates that Non-Ionic Surfactant (NIS) at 0.25% volume/volume and 2.5 to 4 lb. of AMS should be added to increase efficacy. There is a six-day waiting period that must be followed if using a 6-oz. rate of Select Max. If corn needs to be replanted immediately, then Gramoxone with Sencor is the best option.

https://cropwatch.unl.edu/2018/impacts-volunteer-corn-crop-yields

Resources:
Liu, W. et al. 2004. Crop Sci. 44:847-854.
Thompson, A. and L. Steckel. 2008. Replanting Corn in a Failed Roundup Ready Corn Stand. W164.
Retrieved from 

https://extension.tennessee.edu/publications/Documents/W164.pdf

PowerMAX® is a registered trademark of Monsanto Company. Select Max® is a registered trademark of Valent U.S.A LLC. Sencor® is a registered trademark of Bayer. Liberty® is a registered trademark of BASF. Gramoxone® is a registered trademark of Syngenta.
