'Proceed at Own Risk' if Plant Soybeans after Corn Herbicides

Most labels prohibit coming back with corn.

Published on: Jun 11, 2008

The safe date for planting corn is passed in most areas. Evn the long-shot date is slipping by quickly. If you've got a field where corn herbicides were applied and it's too alte to platn corn, does it make sense to gamble planting soybeans instead?

Apparently you're on your own if you do so. Official word from Purdue sources is that there may be a couple of herbicides that don't mention a plant-back restriction for soybeans following corn. Otherwise, nearly everyone does, and the official stance is that you should follow the plant-back restriction listed on the label. For most herbicides, the restriction for planting back to soybeans is several months. That would eliminate giving it a try as an option.

That's the official word, and if you try it, you're obviously on your own. Chemical representatives are bound by law to point to the label for their respective product as well. Of course, plant-back restrictions aren't typically based on a summer with 14 inches of rain, sometimes within one week during the first week of June.

One source says it's possible that anaerobic bacteria operating in saturated soils would break down most herbicides. But that's theory and speculation, and certainly not discussed in this context on herbicide labels.

However, hang around the coffee shop long enough and you will likely find someone who knows someone who's neighbor tried planting soybeans after corn one year, who knows when, and it worked. It's the kind of documentation that normally you would ignore. But these are desperate times this spring.

Indiana Prairie Farmer did carry a story a few years ago about a farmer who planted corn that was sprayed. He planted around June 1. Then he received five inches of rain in a few days on the 30 acre, somewhat poorly drained field. His stand was terrible, and by the time the field was dry enough to replant, he was past the point of no return on the calendar, much like many are right now.

So he planted soybeans. And he saw no ill effects! We even saw the field. It made average yield for that particular season. He never did see any signs of injury. Was he lucky? Perhaps? Did the rain leach the herbicide down below the root zone, or did the herbicide break down more quickly because of the deluge of rain?

There aren't answers for this riddle. There is also no recommendation to plant soybeans after corn herbicides anywhere within our reading area. You're truly on your own on this decision.