Progress of Corn Planting and Corn Emergence
By Roger Elmore
02 May 2012 -
Two questions about corn
1. Is the corn planting window closing?
2. What about corn that is already planted?
As of Sunday, USDA-NASS reported half of Iowa’s corn lay in seed beds, the other half in seed bags. That rate puts us 18 percent ahead of the five-year average. Forty-one percent of our anticipated crop was planted in one week, with only 4.3 days suitable for fieldwork. If we can use that number for days corn was planted, that’s 5.9 million acres in 4.3 days or 1.37 million acres per day. Proving we can plant a lot of corn quickly in Iowa when conditions are right. Unfortunately, forecast conditions this week aren’t too favorable right now. How should we think about this?
Corn already planted
By April 22 we had nine percent of Iowa’s corn planted. Four percent of that was planted between April 16 – 22, four percent between April 9 – 15, and 1 percent prior to April 8. Depending on your specific location, all of the corn planted prior to April 15 should be emerged or very close to emerging now based on average heat unit accumulations across the state. However, heat unit accumulation (growing degree days or GDD) has been a bit less in the northern third of the state, so corn in those areas planted before April 15 may be close to emergence but not quite there yet. It takes about 90 – 120 GDD’s from planting to emergence.
Corn planted after the April 15, including that planted last week, should be well along in the germination process but not yet emerged. For more information on this, read the article Elwynn Taylor and I wrote about corn’s germination process.
Once emergence occurs, evaluate plant stands carefully – whether you expect good emergence and seedling survival or not. Poor stands and plant-to-plant variability lower yield potential. However, depending on the potential date of replant, keeping the surviving stand may be the best option – even with variable plant heights and development.
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