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Here’s how to flag corn emergence

Corn Watch: Learn valuable insights by flagging plant emergence in several spots.

Tom J. Bechman, Midwest Crops Editor

May 2, 2023

3 Min Read
yellow rope and pile of white flags lying in dirt
WAITING FOR CORN: The Corn Watch ’23 field will again include a study on emergence. A 1/1,000-acre plot is marked off with rope. Flags are ready. All plants that emerge within the first 24 hours will be marked with a white flag. Tom J. Bechman

Small colored flags stuck in a young cornfield are a more common sight today. If you see this while driving by a neighbor’s field, odds are your neighbor is flagging corn emergence.

“More people are realizing how important it is for corn to emerge uniformly,” says Dave Nanda, a retired plant breeder and director of genetics for Seed Genetics Direct, Jeffersonville, Ohio.

Seed Genetics Direct sponsors Corn Watch. Through this project, Nanda visits the same field in central Indiana several times during the growing season, making observations that could relate to other cornfields around the region. The 2023 season marks the third year for flagging corn emergence in the Corn Watch field.

“It’s not that difficult,” Nanda explains. “We have made interesting observations so far by flagging corn emergence.”

Here are Nanda’s best tips for how to flag a cornfield for emergence:

Mark off 1/1,000 acre along a row. “I use a yellow rope with metal stakes on each end,” he says. “It’s marked at 17 feet, 5 inches for 30-inch rows. You could use a tape measure.”

Check more than one row. “You can do pairs of rows, blocks of four or whatever you like,” Nanda says. “One year, we did 24 rows, which was one complete planter pass. There can be row-to-row differences in uniformity of emergence, either related to soil type, differences in planter performance row to row or both. Just checking one row isn’t enough.”

Use different colored flags for each day. Hopefully, most plants emerge within 24 hours, so have extra of your first color on hand. Return to the field daily, putting a flag by each new plant that has emerged.

Keep good notes. Record the color of flag used each day. You may think you can remember, but don’t count on it, Nanda advises. Write it down.

Lessons learned through flagging

Here are four things Nanda has learned through flagging:

1. Year-to-year differences can be huge. In 2021, the first corn took 11 days to emerge. In 2022, the first corn appeared in six days, and about 90% was emerged in seven days. “The weather after planting was cool and wet in 2021,” Nanda recalls. “In 2022, it was unseasonably warm, with air temperatures in the mid-80s. Germination was much quicker in ’22.”

2. Emergence window varies year to year. Nearly 98% of all plants that emerged were flagged within the first two days in ’22, when it was warmer, Nanda says. In ’21, emergence was spread over 14 days or more. “Cool, wet weather really slows things down,” he says.

3. No-till fields emerge about 24 hours slower. In two of the three years Nanda flagged emergence, he compared no-till and conventional fields. In both ’21 and ’22 — two very different seasons — no-till emerged, on average, a day later than conventional corn.

4. Late-emerging plants tend to have smaller ears. “The trend is there, but it is not as drastic as some commercial companies imply,” Nanda says. “Typically, if a plant is four to five days behind its neighbor, ears will be somewhat smaller. Occasionally, a plant emerging that late won’t produce an ear, acting like a weed. Even emergence is important, but so are other factors, including even spacing along the row.”

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About the Author(s)

Tom J. Bechman

Midwest Crops Editor, Farm Progress

Tom J. Bechman became the Midwest Crops editor at Farm Progress in 2024 after serving as editor of Indiana Prairie Farmer for 23 years. He joined Farm Progress in 1981 as a field editor, first writing stories to help farmers adjust to a difficult harvest after a tough weather year. His goal today is the same — writing stories that help farmers adjust to a changing environment in a profitable manner.

Bechman knows about Indiana agriculture because he grew up on a small dairy farm and worked with young farmers as a vocational agriculture teacher and FFA advisor before joining Farm Progress. He works closely with Purdue University specialists, Indiana Farm Bureau and commodity groups to cover cutting-edge issues affecting farmers. He specializes in writing crop stories with a focus on obtaining the highest and most economical yields possible.

Tom and his wife, Carla, have four children: Allison, Ashley, Daniel and Kayla, plus eight grandchildren. They raise produce for the food pantry and house 4-H animals for the grandkids on their small acreage near Franklin, Ind.

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