Crop update from southwest Iowa

June 7, 2016 10:22 AM
Blog Post

Most of the corn is around V3 to V6, with some of the replant corn popping up with the heat. I think (hope) I saw my last replanted corn being put in yesterday, some wet spots that had dried out on the edges of some bottom fields.

Spraying corn

A lot of corn spraying is going in, and of course, as always, it is windy. Hopefully operators can get out early in the morning and towards evening on the windiest days to help minimize drift issues. Having run a coop for nearly a decade, I know all this is easier said than done. Buffer zones, drift agents, and low drift nozzles help a lot. Good luck with getting the corn wrapped up, and then we can head into bean spraying.

Applying additional nitrogen

We are seeing a lot of “wavy” or up and down and light to dark colored green corn in many fields, with some showing patterns related to tillage and/or NH3 applications. We tend to see more of this in cool, wet springs; I think a lot of it has to do with slower mineralization of soil nitrogen (N). Typically this is transient, and as we get some warmer temps, a little drier weather, and some deeper root growth, things usually even out. We’ve seen a few fields where it is pretty profound and growers are wondering if applying additional N will help out. This is a hard question to answer, and as usual, I preface anything related to this with “it depends.” John Sawyer recently authored an ICM Blog with some good insight on the issue: Precipitation and nitrogen this spring.

Dicamba resistant soybeans

I have a lot of clients who gave the new dicamba resistant soybeans a shot this year, they are starting to think about weed management in them. Remember that we didn’t get clearance from the EPA to spray dicamba of any type on these beans; hopefully next year we can give that a try. About all we can do right now related to dicamba is use these genetics as a chance to hit weeds in waterways, terraces, and fencerows harder than usual. We can use labeled dicamba applications in these noncrop areas, and, the good news is, if we are next to dicamba resistant beans we won’t see the typical injury symptoms that often accompany broadleaf control in the noncrop areas adjacent to soybeans.

Please don’t hang a boom out into the beans though. That would be an off label application, and I don’t want any of my clients to be on the EPA’s radar over any mistakes made with this new technology!


See the latest crop progress report from the ISU Extension and Outreach crops team: Regional Update: Crop Progress for May 30 to June 6, 2016


Clarke McGrath On-Farm Research and Extension Coordinator - Iowa Soybean Research Center

Clarke McGrath currently serves as the On-Farm Research and Extension Coordinator.

Prior to joining Iowa State University, McGrath spent nearly a decade as a retail agronomist and manager in the GROWMARK system, earni...