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Corn Illustrated: Here are solid reasons for scouting and tips to get you started.

Dave Nanda

April 26, 2022

3 Min Read
yellow rope lies between rows of corn
COUNT PLANTS: Notice the yellow rope between two rows. It’s premarked to 17 feet, 5 inches so it’s easy to count plants per 1/1,000 acre. Tom J. Bechman

Growing a good corn crop is like raising thousands of babies, but it’s more difficult! Babies start talking eventually and can tell you what they need. Corn plants depend on you, Mother Nature and nutrition from the soil. You must provide what’s needed based on soil tests, yield goals and genetic potential of the hybrids.

Warm and wet conditions in your area set up corn for diseases. Cool and dry conditions set it up for other issues. Grab a resource book and bring along your cellphone with a scouting app. One good resource book with pictures is the Purdue University Corn & Soybean Field Guide. The 2022 edition is available now. Two apps, Corn Field Scout and Soybean Field Scout, are available at nominal cost. Take a shovel and a few plastic bags, too.

Here are some more scouting tips:

Determine growth stage. Count leaves to determine growth stage. I prefer counting the uppermost leaf with a collar as the final leaf. Knowing growth stages can help you make determinations as to when the growing point is above ground, and perhaps if it’s still OK to apply postemergence herbicides. The growing point generally comes above ground around V5. Afterward, corn is vulnerable to hail and frost damage.

Take stand counts. Even if it’s too late to replant, this is useful. In some cases, you can get a handle on planter performance based on stand counts and plant spacing. To make it easier, carry a rope premarked to 17 feet, 5 inches for 30-inch rows. That represents 1/1,000 of an acre. If you count 30 plants per row within that distance at random locations, it represents 30,000 plants per acre.

Dig small and missing plants. If a plant is small or misshapen, dig it up to determine why it isn’t normal. The root growth pattern provides clues. Perhaps the seedling encountered crusting and leafed out underground. Or perhaps it was affected by chemical injury.

Yes, you can dig for missing plants! If there is no plant, dig carefully with a pocketknife or trowel, looking for seeds. My experience is that at least 80% of the time, you will find a seed — it’s not a planter skip. Remember, germination is often 95%, not 100%.

Confirm nutrient shortages. If you find plants showing classic signs of nutrient shortage such as purpling, usually indicative of a phosphorus deficiency, it may or may not be important. Sometimes these are situational deficiencies caused by weather conditions. The plant is truly short on phosphorus, but when weather conditions improve, the deficiency will disappear. Purpling doesn’t always mean there is a true deficiency in the soil.

Should you find striping that you suspect is sulfur deficiency but you want to be sure, collect about 25 leaves from both areas with and without stripes. Put them in your plastic bags, and later transfer them to sampling bags. Send them to a lab for verification of a sulfur deficiency.

Look for disease lesions. The sooner lesions appear, the more likely disease could cause economic harm later. Scout regularly to monitor development. Gray leaf spot is always a threat. Now, also keep an eye open for tar spot. Refer to the field guide and scouting app for pictures of these diseases in early stages.

Nanda is director of genetics for Seed Genetics Direct, Jeffersonville, Ohio. Email [email protected] or call 317-910-9876. Please leave a message.

About the Author(s)

Dave Nanda

Dave Nanda is director of genetics for Seed Genetics Direct, Jeffersonville, Ohio. Email [email protected] or call 317-910-9876. Please leave a message.

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