Released June 8, 2009
ST. PAUL, Minn. — Significant populations of volunteer corn have been reported in some fields this year. Strong winds that blew corn down last fall just prior to harvest likely contributed to the increase. If volunteer corn is present, be sure weed management strategies address this potential yield robber.
If volunteer corn is present in Roundup Ready (RR) soybeans and the corn you planted last year was a RR or a RR/Liberty Link (RR/LL) hybrid, you will need to use either a postemergence grass herbicide as a tank-mix partner or cultivate to control the volunteer corn. If you followed Liberty Link (LL) or RR/LL corn with LL soybeans, control options are the same as above. If you planted conventional corn last year, glyphosate (in RR soybeans) or Ignite (in LL soybeans) will provide control of the volunteer corn.
If you need to add a postemergence grass herbicide as a tank-mix partner to control volunteer corn in soybean, be sure to refer to the product label for the recommended application timing, rate and adjuvants.
If you planted any of the same corn herbicide technologies this year as last year and wish to control volunteer corn, cultivation is your only option. If you rotated LL and RR technologies, glyphosate can control LL volunteer corn and Ignite can control RR volunteer corn, although Ignite may not be as effective due to its contact activity.
Just how much can volunteer corn affect yield?
Research conducted at South Dakota State University in 2007 found that volunteer corn densities ranging from 800 to 14,000 plants per acre reduced soybean yield from 0 to 54 percent and corn yield from 0 to 13 percent. Research conducted at the University of Minnesota in 2007 found similar results in corn, with yield losses ranging from 0 to 14 percent at Lamberton and 0 to 19 percent at Waseca. Yield losses were highest at volunteer corn populations of 19,348 and 21,152 plants per acre at Lamberton and Waseca, respectively.
For further details on volunteer corn management, check out the U of M Extension Crop News article “Volunteer Corn Management in Corn and Soybean” by Jeffrey Gunsolus at http://blog.lib.umn.edu/efans/cropnews/. Research results from U of M weed management trials on volunteer corn control can also be found on the Applied Weed Science website at http://appliedweeds.cfans.umn.edu/. Look under Research Reports/Soybean/2007 and 2008.
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http://www.extension.umn.edu/extensionnews/2009/volunteer-corn.html
Contacts: Lizabeth Stahl is a crops educator and Jeffrey Gunsolus is a weed specialist, both with University of Minnesota Extension.
Catherine Dehdashti, (612) 625-0237, ced@umn.edu
