Volunteer Corn Management

• Volunteer corn has been shown to reduce yields by up to 20% in corn and up to 56% in soybeans if left untreated.  
• Minimizing harvest losses, stalk lodging and opportunities for germination are effective measures to proactively manage a potential volunteer corn escape the following season.  
• Each management strategy for volunteer corn must be tailored to the specific crop being planted next, with respect to the traits incorporated into it. 

Volunteer corn is a competitive weed that deprives corn and soybeans of water, nutrients, light and space, which consequently reduces yield. Management of volunteer corn plants has traditionally involved a combination of cultural and mechanical practices. Herbicide-tolerant crops now offer more volunteer corn management options with non-selective herbicides that control all treated plant material. Managing via herbicide-tolerant crops requires more advanced planning, because most volunteer corn will be tolerant to non-selective herbicides, such as glyphosate or glufosinate, if the hybrid planted in the prior year contained traits resistant to those herbicides.

The Golden Harvest® Agronomy in Action research team conducted trials to understand the effect of volunteer corn on both corn and soybean yields. Trials were conducted in Iowa, Illinois and Nebraska using volunteer corn arranged in consistent patterns and various densities. Conventional corn, not having any herbicide tolerance, was harvested the previous fall for use as volunteer corn. The corn hybrids used in the trials were herbicide-tolerant to both glyphosate and glufosinate. Comparisons were made showing the effectiveness on volunteer corn between the 2 non-selective herbicides. Multiple herbicide application timings were used to evaluate the importance of application timing on volunteer corn.  

Effect of Volunteer Corn on Corn and Soybean Yields 

• Volunteer corn reduced corn yield by up to 20% (Graph 1). 
• Volunteer corn reduced soybean yield by up to 56% (Graph 2). 
• Volunteer corn became more competitive in both corn and soybeans as the density increased. 
• Low densities of less than 2 individual volunteer plants did not economically affect corn yield while all densities reduced soybean yield significantly. 

Application Timing is Critical 

Like any other weed, volunteer corn starts competing with crops at early growth stages, so it is imperative to control volunteer corn early in the season to maintain corn and soybean yield potential.   

Application Timing Influence on Corn and Soybean Yield

Controlling volunteer corn at 6” versus 12” tall helped increase: 

• Corn yields by 4% (Graph 3).
• Soybeans yields by 7.5 bu/A (Graph 4).

Controlling volunteer corn early reduces competition and increases potential yields for corn or soybean crops. 

General Strategies to Reduce and Manage Volunteer Corn 

• Use Agrisure Viptera® corn hybrids to manage insect damage that could contribute to ear drop from insect feeding in the ear shank. 
• Use Agrisure Duracade® hybrids alone or in combination with Force® insecticides to prevent root lodging from corn rootworm damage.  
• Schedule field harvest based on scouting for fields at an elevated risk of lodging and ear drop. 
• Properly adjust combine to minimize harvest losses. 
• Complete fall tillage early to promote volunteer growth before a killing freeze. 
• Consider no-till to minimize seed-to-soil contact and reduce volunteer germination.  
• Graze cattle in fields with lodging and ear drop to minimize germination of volunteers the following year. 
• For fields with high quantities of dropped corn, delay field planting to allow early germination prior to planting. 

​​​​​​​Managing Volunteer Corn in Corn
If volunteer corn wasn’t successfully managed the previous year and rotating to soybeans is not an option, there are limited herbicide options that exist for controlling volunteer corn in corn crops. It is important to have good planting records from the previous year to understand the herbicide tolerance of the volunteers in the current field.   

1. No herbicide trait the prior year: If an herbicide-tolerant hybrid was not planted the previous year, an opportunity exists to plant a hybrid with gylphosate or glufosinate tolerance to manage volunteer corn.
2. Previous year hybrid only contained glyphosate tolerance: Many herbicide-tolerant corn hybrids offer tolerance to both glyphosate and glufosinate. However, some only offer glyphosate tolerance and do not provide tolerance to glufosinate. A solution for fields where these traits were planted in the prior year is to plant an Agrisure® traited hybrid containing tolerance to both glyphosate and glufosinate and make a timely application of a glufosinate-based herbicide to manage small volunteer corn plants (Figure 2). Consult the bag tag labels for Agrisure® E-Z Refuge® product herbicide options, and always read and follow label and bag tag instructions. Only those labeled as tolerant to glufosinate may be sprayed with glufosinate ammonium-based herbicides. 

Managing Volunteer Corn in Soybeans

Volunteer corn resulting from any traited hybrid in soybeans can be controlled effectively with several graminicide herbicides, although the potential control can be reduced when applied in a tank mix with an auxin herbicide¹ (Figures 3 and 4).

​​​​​​​In Roundup Ready 2 Xtend® soybeans or XtendFlex® soybeans, Fusilade® DX herbicide is available for use as a tank mix partner with XtendiMax® with VaporGrip® Technology, which requires a drift-reducing adjuvant, or Engenia® herbicide. Fusilade DX herbicide may also be tank mixed with Enlist One® or Enlist Duo® herbicides and offers superior control of volunteer corn with less risk of antagonism over Clethodim 2EC herbicide. In Enlist E3® soybean systems, refer to EnlistTankMix.com for other approved graminicide herbicide tank mix partners with Enlist One or Enlist Duo herbicides. Liberty® herbicide (glufosinate) may be used to control volunteers in Enlist E3 soybeans and now XtendFlex soybeans, but not Roundup Ready 2 Xtend soybeans. It will only be effective if the hybrid corn planted the prior year was not LibertyLink®. Antagonism has not been documented between graminicides and glufosinate herbicides, however, glufosinate control can be impacted by factors such as application time of day, relative humidity and cloud cover.  

For more information on managing volunteer corn, contact your local Golden Harvest Seed Advisor. 

Photos are either the property of Syngenta or used under agreement. 
Syngenta hereby disclaims liability for third-party websites.
The trademarks or service marks displayed or otherwise used herein are the property of a Syngenta Group Company. All other trademarks are the property of their respective owners. 

References: 

¹Underwood M., N. Soltani, D. Hooker, D. Robinson, J. Vink, C. Swanton, and P. Sikkema. 2016. The addition of dicamba to POST applications of quizalofop-p-ethyl or clethodim antagonizes volunteer glyphosate-resistant corn control in dicamba-resistant soybean. Weed Technology, 30(3), 639-647.