By William S. Curran
Choices for post-grass herbicides and the correct rates to control volunteer corn depend on the height of the corn.
As the soybean crops continue to mature, volunteer corn is rearing its head in some fields. We assume that most of the volunteer corn is glyphosate- and glufosinate-resistant so we will not spend time going over all the options for killing the various types of volunteer corn. In general, the most logical choices to control volunteer corn in any kind of soybean are the post-grass herbicides (e.g., Assure II, Select, clethodim, Fusilade, etc.). Below are some rates to consider depending on the height of the volunteer corn:
| Product | Volunteer corn height | Rate/acre |
|---|
| Select Max 0.97EC | <12 inches | 6 fl oz |
| | 12-24 inches | 9 fl oz |
| Clethodim 2EC | 4-12 inches | 4 fl oz |
| | 12-18 inches | 6 fl oz |
| Assure II/Targa 0.88EC | 10-12 inches | 4 fl oz |
| | 12-18 inches | 5 fl oz |
| | 18-30 inches | 8 fl oz |
| Fusilade DX 2EC | <12 inches | 4 fl oz |
| | 12-18 inches | 6 fl oz |
Always include the necessary adjuvants otherwise control will be impacted. In most cases, this will require the addition of a crop oil concentrate (COC) or methylated seed oil (MSO). If crop injury is a concern, a nonionic surfactant (NIS) may be used in place of an oil with Select Max only. Keep in mind if you plan to tank-mix a broadleaf-specific herbicide, the rate of the grass herbicide may need to be increased to overcome possible antagonism.
Source:psu.edu