Managing Volunteer Corn
If your combine was not set for collecting smaller kernels created by the drought, many of them went out the back with the stover, and have performed well in germination tests throughout the field. But now you are planning to take advantage of the high market prices and the crop insurance guarantee for 2013 wheat, and have a lush green field of volunteer corn in the way. Normally it could be burned down with either Round up or Liberty, but your 2012 corn had both glyphosate and gluphosinate tolerance and its offspring carry those genes as well.
Johnson and Legleiter suggest two alternatives.
- Fields containing volunteers following a RR/LL crop can only be controlled with applications of gramaxone or by tillage. Grass herbicides cannot be used to control volunteer corn prior to wheat planting as rotational restriction to wheat vary from 30 to 120 days. If choosing to apply Gramaxone, be aware that applications can result in variable control.
- Fields containing heavy volunteer corn populations that are glyphosate and glufosinate tolerant would be best managed with tillage prior to wheat planting.
The 2012 drought has continued to provide challenges well after the diminished harvest. The lack of moisture means a reduced activation of many herbicides, therefore many have not degraded and will impact both fall-planted wheat, and spring planted crops next year. To know whether you have a problem a bioassay can be conducted on a test crop planted into the soil or soil could be tested for residue. Another problem is the emergence of volunteer corn that may contain genetic tolerance for Roundup and Liberty, meaning it can only be managed with a heavy dose of gramoxone or tillage.
Source: FarmGate blog