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Cool temps spread out corn emergence

May 25, 2021

Corn Watch: Corn planted on April 24 emerges, albeit slowly.

By: Tom J Bechman

Brightly colored flags with green, white, red and blue markings flapping in the breeze are a cool sight if you’re watching the Indianapolis 500 race. They’re not such an encouraging sight when they are tiny flags attached to wires, each one stuck in the soil by a corn plant. The different color patterns represent when various plants emerged. The more variation in color, the longer it took some plants to emerge, and the less uniformity in emergence.

That’s typically not a good thing, but keep following these Corn Watch ’21 articles throughout the season to see how things play out. Last year, to try out the flag-marking concept, a couple of rows in a field planted around April 20 were monitored, with each plant marked with a flag. It wasn’t the Corn Watch ’20 field. Temperatures were relatively cool then too, and it took a full week before all plants emerged. Yet when Dave Nanda checked that location at silking time in 2020, only one plant — one that emerged a full week late — appeared to have a smaller ear. Nanda is director of genetics for Seed Genetics Direct, sponsor of Corn Watch ’21.

Related: Assess corn progress in your area so far

There was an emergence plot in the Corn Watch ’20 field as well. It was planted in mid-May, and emergence was much more uniform in most of the 12 rows checked. At harvest, when some of those rows were harvested by hand and ears were weighed, there was a trend toward smaller ears for plants that emerged three or more days late.

“The difference wasn’t as big as I expected,” Nanda says. “There was also a difference in ear size based on plant spacing. That can be just as important. We will be tracking both factors this year.”

Extended emergence

The 2021 Corn Watch field was planted April 25. Half the field was conventionally tilled following soybeans, and half was no-tilled into soybean stubble. The original plan was to follow emergence on a full pass — 24 rows — in no-till. Once in the field, eight rows of the conventional-tilled side were marked off for flagging as well.

Plants were still emerging at press time, and final counts haven’t been made. Based on observations so far, here are four preliminary conclusions:

1. Conventional tillage had a one-day jump. Plants starting peeking through the soil on conventional rows one day before any plants were detected in the no-till rows.

2. Plants emerged on both sides sooner than expected. Given cool weather conditions, two weeks to see first emergence would not have been a surprise. Instead, the first plants in conventionally tilled rows emerged in 10 days, and the first plants in no-till rows emerged in 11 days.

3. There appears to be a row-to-row difference. Some rows emerged more uniformly than other rows. The planter is equipped with the DeltaForce hydraulic down-pressure system. The difference seems to be more pronounced on the no-till side, but final numbers on total emergence and days to emergence aren’t in yet.

4. Total percent emergence appears slightly higher on conventional till. Again, this is an early observation. Come back and read more once final numbers are in to see if this apparent trend holds. It appears final stands on both sides of the field will be acceptable.