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Why V5 corn stage is so important

Corn Commentary: Can you identify corn’s growth stages? Here’s why it’s crucial to learn how.

Tom J. Bechman, Midwest Crops Editor

June 4, 2024

3 Min Read
A close-up of a corn plant with leaves
COUNT COLLARS: This corn plant has five leaves with collars, making it a V5 plant.Tom J. Bechman

Whether it’s Mark Licht at Iowa State University or Justin McMechan at the University of Nebraska, top-notch agronomists emphasize that staging growth of corn is critical for several reasons. For example, it plays a role in assessing hail damage. Before and at the V5 growth stage, corn has a much better chance of recovering from hail with little or no potential yield loss than at later stages.

Why? “It is all about the growing point,” says Dan Quinn, Purdue Extension corn specialist. “The growing point is typically below the soil surface until somewhere between the V5 and V6 growth stage. If it’s belowground, it’s protected from aboveground risks, including hail. Once the growing point is aboveground, corn plants are more vulnerable.”

If hail hits before the growing point emerges, both Licht and McMechan say there is a good chance plants can regrow. Both note that the key is waiting a week or more to see if new leaves emerge from the whorl.

Get growth stage right

Quinn refers to the Purdue Corn and Soybean Field Guide for pointers on how to stage corn early in the season. It prescribes the leaf collar method, first described by Iowa State agronomists.

“Count leaves with visible collars,” Quinn explains. “Start with the first true leaf, which is shorter than the rest and has a rounded tip. Then count leaves with fully developed leaf collars.”

Related:Do you know soybean growth stages?

According to the Purdue guide, the leaf collar is a light green to yellowish band that appears near the stem of the plant, at the junction of the leaf blade and leaf sheath. Using the leaf collar method, a top leaf that doesn’t yet have a collar isn’t counted.

Leaf stage matters

Here are more reasons why early vegetative stages are crucial in corn:

Herbicide decisions. Labels referring to plant growth stage vs. height are more accurate. So many factors affect plant height, Quinn says.

Root system shift. About V3, plants begin a transition from relying on carbohydrates in the seed to relying on nodal roots for nutrition, Quinn explains. The shift usually isn’t complete until around V6.

Plant changes. Around V4, internode elongation kicks in, ramping up at V5. Then, at V6 or slightly after, tassel initiation and growth, ear initiation, and kernel development all kick in.

“These early vegetative stages are critical to plant development and yield potential,” Quinn says.

Across the rows

If you have some fields with V5 corn and other fields just emerging, you are not alone. Here are early-season observations from across the Midwest.

In Iowa. “Farmers took advantage of short work windows, and 85% to 90% of the corn was planted by May 21. Weed control has been a challenge, with just small windows of low wind and dry fields occurring. Issues with weed control might arise because of late or missed applications, or excessive rainfall following applications.” — Leah Ten Napel, ISU Extension field agronomist, northwest Iowa

Related:Diagnose fertilizer burn in corn

In Missouri. “We’ve been wet and were hammered with rain again. Several farmers faced replant decisions and some replanted. There may be concern about nitrogen loss due to excess rain in some areas.” — Mindy Ward, editor of Missouri Ruralist.

In the Dakotas. “One farmer in the eastern Dakotas reported his corn and soybeans were one-third in, wheat was planted, but canola was still in the bag. In general, farmers don’t want to mud things in, but don’t like the prospect of prevented planting.” — Sarah McNaughton, editor of Dakota Farmer

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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