So just how much yield loss comes from volunteer corn?
In Roundup Ready®, Xtend® or Liberty® beans, volunteer corn from the previous corn crop can cause yield loss. However, applying a grass herbicide with your post herbicide application is an easy fix.
So how much yield loss comes from volunteer corn? Recent reports show us the numbers.
University of Nebraska:
  • Volunteer corn density of 3,500 plants/acre led to 10% yield reduction in soybeans.
  • Doubling the density to 7,000 plants/acre led to a 27% yield reduction.
  • A density of 3,500 clumps (dropped ears) of corn/acre resulted in a 40% yield reduction.
  • The greatest yield reduction occurred when volunteer corn was left uncontrolled or when it was controlled too late at the R2 soybean growth stage.
South Dakota State University:
  • Volunteer corn density of 5,000 plants/acre resulted in a 20% yield reduction (12 bu/acre yield loss in 60 bu/ac soybeans).
  • Natural clumps of volunteer corn (associated with dropped ears) led to greater yield loss as they were more competitive than individual plants.
Universities of Minnesota and Illinois
  • There was greater competition with clumps of volunteer corn versus individual plants.
  • Clumps of corn (7 – 10 plants/clump) were established at different densities and soybean yield was reduced 1% for every 75 – 115 clumps/acre.
Controlling volunteer corn:  Since Roundup Ready adoption two decades ago, we should all be well-versed in controlling volunteer corn in soybeans. There are many grass herbicides labeled for this use in Roundup Ready and Ready 2 Xtend® soybeans: Select Max®, Poast®, Assure II, Fusilade® and Fusion® are labeled for this use.
If you planted LibertyLink® soybeans, Liberty can control volunteer corn, but only if the previous corn control did not carry the LibertyLink trait. Sometimes the LibertyLink trait comes naturally with the Roundup Ready trait, so you may have purchased a Roundup Ready corn hybrid without realizing it also carries the Liberty trait. The Liberty label allows a maximum of 87 fl. oz./acre per growing season and 2 applications can be made if necessary, each with 32 to 43 fl. oz./acre on soybeans carrying the LibertyLink trait.
Soybean agronomist Dr. Daniel Davidson posts blogs on agronomy-related topics. Feel free to contact him at or ring him at 402-649-5919. 

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About the Author: Dan Davidson

Soybean agronomist Daniel Davidson, Ph.D., posts blogs on topics related to soybean agronomy. Feel free to contact him at or ring him at 402-649-5919.