• Crop Protection
  • May 06, 2019

When Corn Becomes a Weed

Farmer and Retailer holding a corn plant
Volunteer corn plants are a nuisance for soybean growers because they grow quickly and are difficult to manage. Left uncontrolled, volunteer corn can lead to yield loss and also serve as a host for corn rootworm larvae. Timely herbicide applications are essential to managing volunteer corn in soybeans. In order to be effective, herbicides must penetrate corn’s waxy cuticle, which requires good spray coverage with the right products.
Here are a few tips to rid your soybean fields of volunteer corn plants that can rob yield.

1. Reduce volunteer populations. 

Limit the number of dropped ears by protecting plants from insects and diseases that can promote weak roots and stalks. That may mean adding a fungicide or insecticide spray to your corn management program. Avoid ear and kernel loss at harvest by properly maintaining equipment and adjusting combines for field conditions.

2. Treat volunteers promptly. 

Corn can quickly outcompete soybeans if left untreated, leading to yield loss. A study by the University of Nebraska showed 5,000 volunteer corn plants per acre reduced soybean yield by approximately 20 percent.1   

3. Use the right products. 

The waxy cuticle of corn plants can make them difficult to treat if you don’t use the right products. Section® Three herbicide combined with StrikeLock® adjuvant from WinField United is an excellent option for controlling volunteer corn. Grassy weed herbicides, including Section Three, require the use of a high-surfactant oil concentrate for effective control. The addition of StrikeLock adjuvant helps the grass herbicide penetrate waxy corn cuticles for better coverage and control, while also providing industry-leading drift and deposition performance.

4. Apply the right herbicide and adjuvant rates. 

Depending on the size of the volunteers you’re trying to manage, you may need to increase herbicide and adjuvant rates to be effective. Increasing the spray volume can help ensure adequate coverage of volunteer plants. Herbicide and adjuvant rates vary according to conditions and tank mix partners, so consult with your local agronomist for specific treatment recommendations. 
Volunteer corn can be managed with timely action and the right products. Consult with your locally owned and operated WinField United retailer or your trusted advisor to learn about cost-effective ways to keep your soybean fields clean.

Editor's Note: This article was originally published in April 2018 and was updated in May 2019.
1. J. Alms, M. Moechnig, D. Deneke, D. Vos. “Volunteer corn effect on corn and soybean yield.” North Central Weed Science Society, 2008. Abstracts Volume 63.
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