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Waiting for Small Grains and Corn to Emerge (05/23/19)

Good planting progress was made last week, but significant acreage still remains to be planted. Not only has planting been delayed this spring in most of the state, temperatures have been significantly cooler than normal.

Good planting progress was made last week, but significant acreage still remains to be planted. Not only has planting been delayed this spring in most of the state, temperatures have been significantly cooler than normal. Wheat growing degree days (GDDs) are running 70 to 120 behind normal and corn GDDs between 40 and 70 behind normal (assuming a May 1st planting date). Therefore, most of what has been planted has yet to emerge. When can we expect to observe emergence in fields that have been already been or that will soon be planted? Corn requires between 115 and 120 GDD before it emerges. For corn planted on May 1st (I know there was little corn planted this early), we should expect to see emergence around the 23rd of May. For corn planted on the May 15th, we might see emergence as early as May 25th or as late as June 3rd (that is the range based on the past 30 years of weather data). The predicted “average” emergence date of May 27th for this planting date seems unlikely due to the expected cool weather this coming week. The range in possible emergence dates for corn planted on May 25th is compressed somewhat to between May 31st and June 8th. These estimates, as well as those for wheat that follow are based on weather data from Prosper and should be adjusted depending on where you are in the state and temperatures there, relative to Prosper.

Wheat requires 180 GDDs before it emerges (corn and wheat GDDs are calculated using different base temperatures so wheat GDDs accumulate more rapidly than do corn GDDs). Wheat planted on May 1st should have emerged on or near May 13th (three days later than normal). Using “normal” weather data, wheat planted on May 15th should emerge around May 23rd and wheat planted on May 25th should emerge near May 31st.

These latter predicted dates are likely to be off slightly due to the cooler than normal weather that is predicted for the region, but they should give you a rough idea of when to expect emergence. Temperature is not the only factor to affect emergence date. Seeding depth and residue cover can also impact the actual date of emergence.

Soon after emergence, evaluating stand establishment can be important for two reasons. The first and most obvious reason is to determine if the stand is adequate to produce a reasonable crop. There are charts available to help you determine the yield potential of sub-optimal stands. The second is to learn how soil and weather conditions and planting practices impacted stand establishment this year. When “learning” from this year’s experiences, consider soil temperature, residue cover, planting depth, soil moisture, rainfall relative to planting date, planting speed, use of fertilizers with the seed, etc., so that you can better plan for how optimize practices for years that might be similar to this year.

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Evaluating plant stands soon after emergence can provide insight into factors that impact emergence in conditions like those encountered this year.

Joel Ransom

Extension Agronomist, Small Grains and Corn

 

This site is supported in part by the Crop Protection and Pest Management Program [grant no. 2017-70006-27144/accession 1013592] from the USDA National Institute of Food and Agriculture. Any opinions, findings, conclusions, or recommendations expressed are those of the website author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture.

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