Follow corn through early growth stages

Corn Illustrated: This slideshow provides a step-by-step guide to understanding how corn develops during the first part of the season.

What happens to the seed once a corn plant sprouts? How many leaves come above ground while the growing point stays below ground? How do you know where the growing point is? Maybe you know the answers to these questions. Even if you do, a refresher never hurts.

Dave Nanda took to the field with his scouting tools to illustrate how to evaluate corn early in the season, stage its growth and get a handle on early-season plant health. Nanda is a crop consultant based in Indianapolis.

Early-season scouting
Come along on this virtual tour as Nanda examines corn nearly four weeks after planting. Warm weather helped this field of corn emerge and grow quickly. A storm damaged leaves, but Nanda expects the crop to recover fully.

Make general observations. The field is advanced for being planted less than four weeks. Growing degree day units accumulate quickly when temperatures are 80 to 86 degrees F during the day and 60 degrees F or higher at night.

Take stand counts. Any good scout wants to know how many plants per acre are in the field. The goal for this field was 32,000 plants per acre. Nanda uses a rope with marks preset for various row widths. The preset distance represents 1/1,000 of an acre. He counts plants in the row on either side of the rope, averages the two numbers together, and then multiplies by 1,000 to get plants per acre.

Evaluate row spacing. You can just get a visual feel for how well plants are spaced, or you can check the distance between plants in sections of row. In this field, plants are evenly spaced in most places. Emphasis on planter maintenance and improved planting technology have made it much less common to find serious problems with doubles, skips and uneven plant placement, Nanda says.

Dig a plant to check planting depth. The seed will still be where it was placed. In this field, planting depth appears to be about 2 inches. Emergence is even, so that seems to have been a good choice based on field conditions at planting.

Check roots. A young five-leaf plant is already putting on a good root system. It has not yet established permanent roots, Nanda notes.

Stage the growth of plants. The first rounded leaf at the base of the plant counts as the first leaf, Nanda says. He prefers the leaf-collar method for staging growth. The plant he dug up and several others had five leaf collars exposed, counting the rounded bottom leaf. So they’re at the V5 stage.

Find the growing point. Plants at the V5 leaf stage should be about ready to send the growing point above the ground. Nanda slices a stem open lengthways with a pocketknife. He finds the tip of the growing point just at ground level. So when the storm hit a few days earlier, growing points were not exposed. If leaves had been destroyed, the plants would have been able to send out new leaves and recover. Once the growing point is above ground, if it is destroyed, then the plant will not regrow.

Examine other leaves. Leaves that will emerge later are working their way up, along with the growing point. They will be the next leaves to come out, Nanda says. However, this plant appears healthy, despite some cosmetic leaf tattering due to wind and possibly a few hailstones.

Click through the slideshow to see photos.

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