Control Of Volunteer Corn Before Wheat Planting

Dr. Larry Steckel

JACKSON, TENN.
The corn yields we have had here on the station as well as what I have heard of in farmer’s fields have been quite good. Even some of my weedy checks are making 160 bu/A! However, I know there are many drowned out areas in the corn that will lower the yield average and likely have stressed corn with small ears that will drop through the snap rollers. With many folks intending to plant wheat behind corn, volunteer corn will likely be a big problem this fall particularly in those areas. Volunteer corn germinating in September can be a weedy mess that makes establishing a good wheat stand this fall a challenge. For the few fields planted to non-Roundup Ready corn hybrids, one can simply apply glyphosate to control the volunteer corn. That only entails a fraction of acres so what are some good options on volunteer Roundup Ready corn?
There are really two good options to control volunteer corn before wheat planting. Finesse at 0.5 oz/A tankmixed with 32 oz/A of glyphosate is a very good option. It will provide good knock down and residual control of volunteer corn as well as most winter annual broadleaf weeds and establishing annual ryegrass. Ryegrass control should be monitored closely after a Finesse application as ALS-resistant ryegrass has become more prevalent in recent years.
The other option is Gramoxone at 40 to 48 oz/A.  Go with the higher Gramoxone rate when volunteer corn is over 10” tall. A residual like Valor can be tankmixed with the Gramoxone up to 30 days before wheat planting. The Valor should provide residual control on pigweed and winter annual broadleaves but will likely let annual rye and Poa escape.  Another residual option before wheat planting to add with Gramoxone is Sharpen. Sharpen at 1 to 2 oz/A may be applied right up to wheat planting. Like Valor, it will provide some residual control of Palmer and winter annual broadleaf weeds but will not help with annual ryegrass or Poa.∆
DR. LARRY STECKEL: Extension Weed Specialist, University of Tennessee