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Sponsored: When Will My Corn Come Up?

With the cool, wet weather many of you have had, emergence is taking longer than usual. Especially in Ohio, it’s tempting to look at the calendar and start to get concerned if your corn isn’t coming up in 7 to10 days like you might have expected. If you are looking at your planted fields and wondering when you will start to see rows of corn, the following information should help you understand when you might expect to see those small green spikes.

The speed of corn emergence is regulated by many factors; one of the most important is temperature. Temperature is measured over time using Growing Degree Units (GDUs), which helps quantify the amount of heat that a young corn plant has been exposed to. To calculate GDUs, first record the daily high and low temperatures. If the high is higher than 86, record it as 86. If the low is lower than 50, record it as 50. You then take the average of the high and low temperatures and subtract 50. This is the number of GDUs gained for that day.

May 10_GDU Equation

After planting, it typically takes 110 to 120 GDUs for corn to emerge. Looking at how GDUs are calculated, you can understand how cool weather slows GDU accumulation and delays corn emergence.

There are several places to get information about GDUs for your own location. If you have a FARMserver™ account, you can access GDU information from the Field Focus page by clicking on Weather Chart. Contact your Precision Farming Field Advisor or call 317/565-4120 if you have any questions.

The Ohio State University also provides daily GDU information on the OARDC website, which you can access here. If you want to do the calculations yourself, find past daily temperature information on weather websites such as Weather Underground. Here you would just enter your zip code and use the Calendar feature.

Waiting for corn to emerge can be a nerve-wracking period of the growing season. While nothing can replace the sense of relief and accomplishment when the corn comes out of the ground, knowing where you stand with GDUs can at least help you feel better about your recently planted crop.

May 10_When Will My Corn Come Up

Corn emerged at the London, Ohio, Practical Farm Research (PFR)® site. These are the first two entries in the planting date study.

Special thanks to Mike Hannewald, Precision Farming Field Advisor, for writing this article. If you have any questions, feel free to contact him at 317/385-2444.

For more agronomic news from Alex Johnson, Beck's Area Team Leader and Certified Crop Advisor, please visit his agronomy blog on 

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