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Know stages of corn growth to fine-tune management decisionsKnow stages of corn growth to fine-tune management decisions

If you know when corn makes decisions, you can manage to optimize higher yield.

Tom Bechman 1

January 7, 2016

3 Min Read

When should you apply nitrogen for corn? Should you apply it all at once, or split the applications? If you're not using a residual herbicide, how soon do you need to have grass and weeds controlled? What happens if you don't have them controlled by then?

Related: In what growth stage is this corn seedling?

These are just some of the questions you may ask when thinking about the corn crop this season. All of these questions have one thing in common – they determine either how much fertility or how much competition corn plants will have when it's time to make key decisions in the life of the plant. How the plant makes these decisions will go a long way toward determining corn yield.


Here are six stages of growth where key decisions are made in the life of a corn plant. Some of these six are actually ranges representing more than one growth stage.

Thanks to Beck's for providing this information in their 2015 Practical Farm Research summary, recently published. Contact a Beck's dealer or attend one of nearly 80 winter meetings planned around the Corn Belt for Beck's customers. For details call 1-800-937-2325.

Thanks also to the 2016 Purdue University Corn & Soybean Field Guide for information about these growth stages.

Key stage one- V3: The nodal root system is being established here. That's important because the seed is no longer the main source of food for the plant. It now obtains nutrients from the soil through roots.

Key stage two- V5: The growing point is above the soil surface. Some sources may say this actually occurs at V5 to the V6 stage. Once the growing point is above the soil surface, the plant is more vulnerable to injury from hail or frost.

Key stage three-V6-V8: Kernels around the ear are established. This depends more on genetics than on the weather. Very severe stress can decrease the number of kernel rows around the ear.

Key stage four- V12-V15: Number of potential kernels along the length of the ear is almost determined by now. Soil moisture and nutrient uptake are critically important here. The number of kernels per row is greatly determined by environment.

Key stage five- R1: Pollen shed begins, and pollen drops onto the silks. Excessive hat or moisture can reduce receptivity of silks to pollen. Silk reduction from insect feeding such as corn rootworm beetles or Japanese beetles is also a concern. Even after kernels are pollinated, they can abort, typically if conditions become unfavorable. Most kernel abortions are usually near the tip of the ear.

Key stage six- R2-R6: This is the grain fill period. Number of kernels has already been set, but size and weight of kernels is now being established. Availability of ample moisture and nutrients are key during this period.

About the Author(s)

Tom Bechman 1

Editor, Indiana Prairie Farm

Tom Bechman is an important cog in the Farm Progress machinery. In addition to serving as editor of Indiana Prairie Farmer, Tom is nationally known for his coverage of Midwest agronomy, conservation, no-till farming, farm management, farm safety, high-tech farming and personal property tax relief. His byline appears monthly in many of the 18 state and regional farm magazines published by Farm Progress.

"I consider it my responsibility and opportunity as a farm magazine editor to supply useful information that will help today's farm families survive and thrive," the veteran editor says.

Tom graduated from Whiteland (Ind.) High School, earned his B.S. in animal science and agricultural education from Purdue University in 1975 and an M.S. in dairy nutrition two years later. He first joined the magazine as a field editor in 1981 after four years as a vocational agriculture teacher.

Tom enjoys interacting with farm families, university specialists and industry leaders, gathering and sifting through loads of information available in agriculture today. "Whenever I find a new idea or a new thought that could either improve someone's life or their income, I consider it a personal challenge to discover how to present it in the most useful form, " he says.

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