Managing volunteer corn prior to wheat planting
Paraquat provides rapid control of vegetation; therefore, it may be preferred over glyphosate if speed of control is desired. Paraquat helps manage volunteers with GMO traits, including glyphosate-tolerant corn. However, paraquat alone tends to be inconsistent in controlling corn that originates from seed that were planted or incorporated in soil. This is often the case when trying to kill corn for replant situations in the spring. Limited research in 2007 showed at least 95% control for corn plants from seeds that were not incorporated into soil. Our current theory is that the growing points of volunteer corn plants originated from seed on or near the soil surface and were exposed to paraquat and other related stresses.
Finesse is another option that has been evaluated for controlling volunteer corn. Finesse is a premix of two ALS inhibitor herbicides (chlorsulfuron + metsulfuron) which is slow in its activity. It is labeled at 0.5 oz/A preplant or prior to emergence of wheat for volunteer corn control up to 18” in height. The addition of a nonionic surfactant at 0.125% to 0.5% with Finesse is required. Research in 2007 on the use of Finesse showed up to 60% control of volunteer corn within 7 days after planting no-till wheat.
Unfortunately frost occurred before Finesse reached maximum activity; consequently, we were unable to determine if the herbicide would have eventually killed the volunteer plants. Additional research on Finesse at 0.5 oz/A in 2011 showed 80% control at 19 days after application. The advantage of Finesse is that it would likely provide residual activity for any later emerging volunteer plants as well as help in managing Italian ryegrass. The rotational crop restrictions for Finesse require an interval of at least 6 months before planting STS soybeans or 18 months for non-STS soybeans and field corn.
Select Max has been discussed as another option for managing volunteer corn. It is labeled to control volunteer corn in soybeans or in preplant applications for field corn; however, it is not labeled prior to wheat planting. Since the Select Max label does not address the use of Select Max for wheat, a minimum of 30 days is required after application before wheat should be planted.