Harvest weed control for corn and soybeans

Farm Forum

This year due to poor spraying conditions, wet planting conditions and increased resistance there are a lot of fields with weed escapes. The fields look a lot like they did in the eighties and early nineties before Roundup Ready was part of our weed control. In those days Harvest aids were looked at to help with combining and reduce viable seed production. At present there are three chemicals labeled to use on soybeans as a harvest aide and three labeled on corn. In Soybeans Gramoxone is labeled for use when 65% of the seed pods have reached a mature brown color. The rate is 8-16 ounces and high rate needed for most weeds. Gramoxone needs to be applied 15 days before harvest and there is not haying or grazing the straw. Aim chemical also has limited activity on a small amount of weeds and a three day harvest interval. Check label for weeds controlled and other restrictions. Lastly Glyphosate does have a harvest aide label. It is seven days till harvest and 14 to 25 days to hay or graze restriction depending upon rate used. Check labels for more restrictions.

In corn Gramoxone is also labeled at a rate of 1.2 to 2 pts. The high rate is recommended for most large weeds. It is to be applied after the corn is black layered. It is seven days before it can be harvested or grazed. 2-4-D is also labeled on corn as a harvest aide you can spray after brown silk on same labels and after blacklayer on others check labels. It is seven days until it can be harvested or grazed. It will only kill broadleaf weeds the Ester form is usually more effective. Glyphosate is also labeled on corn and has a seven day preharvest label and the same for grazing. If you think you have resistant weeds to Glyphosate it would not be a good choice as a harvest aide. Remember to read labels before all applications. For more information check with your regional Agronomy Field Specialist or myself, Paul O. Johnson, at 605-882-5140 or PaulOJohnson@sdstate.edu.