Corn not coming up? Do you need to replant?

Corn not coming up? Do you need to replant?

If you have a disappointing stand, there are good resources available to help make the decision.

After the cold, wet stretch of weather the past week or two, some farmers in Iowa have early-planted corn stands—planted in early or mid-April—that aren’t coming up very well. Looking at these stands on May 6, you see emergence is slow and poor in some areas of some fields. “I’m worried about a few acres in each field, areas of my fields that aren’t coming up very well,” a western Iowa farmer tells Wallaces Farmer. “I hope I don’t have to replant these slow-to-merge and poor-looking stands.”

What about replanting? When and how should you decide?

SLOW EMERGENCE: Planting depth can be a factor for seeds surviving cold, saturated soil. Seeds that are slightly “higher and drier” are able to get some oxygen and survive. This may explain why in some fields the germinating seed survives better than in other fields.

Replanting corn and soybeans is something you hope you don’t have to do a lot of, but if you do have a disappointing stand or a problem stand, there are some good resources available to use to help make those decisions. “That’s easier said than done, but you should try to take a little extra time and make sure what sort of stand you have. Try not to make too hasty a decision either way,” advises Clarke McGrath, Iowa State University Extension agronomist based at Harlan in western Iowa.

Making these stand assessment and replant decisions isn’t easy

Stand assessment and replant decisions are often, almost always, agonizing. “It is hard to leave a stand that is below a grower’s normal expectations. Many of us just don’t like looking at it all year long and are prone to want to ‘start over’ and replant,” he notes.

The flip side of the coin is that if a stand is close to being a “keeper” but you are leaning towards starting over, you have to remember there is no guarantee that the replanted stand will get in the ground and emerge and do any better. “With that said, replant decisions boil down to a step-by-step process,” says McGrath, who offers these guidelines to help you make the best decision for your individual situation.

* Stand assessment—What’s the big picture, how much of the field is impacted, how bad is it in general, is there a chance things will improve or degrade in the next few days?

* Stand counts—Do a solid determination of what sort of viable stand is out there and compare to replant charts to see what the potential yield would be.

* Yield potential—Determine the yield potential of the remaining stand based on its population and planting date, and use available charts to compare with the yield potential of a replant crop with expected plant populations.

* Other factors—Final decisions on whether to replant should also include the costs incurred from a replanted or existing stand. Some factors to consider include costs of replanting (i.e., seed, labor and fuel) and crop insurance. Also take a look at any herbicide restrictions or pest management implications related to the current stand or a replant scenario.

* The decision—After gathering information about the compromised stand and potential replant implications, make your replant decision based on the best economic outcome of the two choices. Will the costs and yield potential of the existing stand have greater revenue than replanting?

“I think this is one of the most important steps that you won’t find in the books the PhD’s write,” says McGrath. “There are never exact or perfect answers, so I also like to have growers use their personal experiences and gut feeling to help make the final decisions. They are the ones with the investment on the line, so their experience and instincts are as valuable as any other step in the process.”

TAGS: USDA Extension
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