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Corn Planting and Emergence (05/21/20)

Planting corn this season has been challenging with only 20% of the planned corn acres planted to date.

Planting corn this season has been challenging with only 20% of the planned corn acres planted to date. Moreover, the extraordinarily cold weather in early May has delayed germination and emergence. Typically, we expect corn to emerge after about 125 growing degree day (GDDs) have accumulated. Sadly, there have been 9 days so far in May (based on Fargo NDAWN station) that produced 2 or fewer GDDs. This compares to the normal rate of 8-10 GDDs per day. Scouting emergence issues in early planted corn fields is advisable this year due to the extra time (days) needed for corn to emerge because of this cold weather and because of concerns about imbibitional chilling injury and freeze injury to germinating seeds. Temperatures this next week, on the other hand, look ideal for corn germination and emergence. Growing degree accumulations are predicted to be well above average (17 per day compared to 10 or 11 per day). Corn planted today (May 18th) should emerge in just over a week. When using GDD to predict when corn should emerge and to help schedule early scouting, consider the following (adapted from Broeske and Lauer, 2020) : 1- Normally emergence occurs after 125 GDDs; 2- In no-till systems add 30 to 60 GGDs due to these soils being cooler than tilled soil at a given air temperature; 3- When planting deeper than 2 inches add 15 GDDs per inch of extra seeding depth; 4- For early planting dates this year add 10-25 GDDs; 5- For planting dates after May 18 this year, subtract 50 GDDs; 6- For dry conditions 30 GDDs.

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Air and soil temperatures are currently favorable for corn planting, but many fields are still too wet. Given that the optimum date for corn planting will soon pass, the desire to plant before soils dry further is compelling. Wet soils compact easily, and sidewall compaction can occur in soils that are wet and/or have been compacted. Roots have difficulty in penetrating and developing normally into compacted sidewalls. Furthermore, seeds may not be adequately covered when the seed-vee cannot be closed by the press wheels. Consider using one (or both) spiked closing wheel to aid in covering seeds in this type of situation.

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Reference:

Broeske, M. and J. Lauer. 2020. University of Wisconsin Visual Guide to Corn Development. Extension, University of Wisconsin-Madison. https://ipcm.wisc.edu/download/pubsGuides/UW_CornDevGuide.pdf.

 

 

Joel Ransom

Extension Agronomist, Cereal Crops

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