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Early-season assessment of corn provides all kinds of information

John Obermeyer, Purdue Extension corn rootworm
POSSIBLE PEST: If you opted to plant corn without underground insect protection, you might find rootworm larvae if you dig after larvae have hatched.
Corn Watch: Ten things you can learn from cornfields early in the season.

Welcome to Corn Watch. You’ll be learning lessons that will help you evaluate how well your own corn fields perform. Topics all season will be based on what’s happening in a single field in central Indiana. It may be the most watched cornfield in the Midwest!

You can follow the field weekly on the Web and monthly in the magazine through harvest. Final yield will be reported, but there’s no yield estimation contest.

Seed Genetics Direct, a new name in the seed business, based in Washington Courthouse, Ohio, sponsors Corn Watch. Dave Nanda, owner of Agronomic Crops Consultants LLC, Indianapolis, will visit the field regularly and offer observations.   

Here are 10 lessons Nanda says you could learn early in the season:

1. A warm winter may lead to higher numbers of certain insects. Insects that overwinter likely had a high survival rate. It could be a good spring for wireworms and similar pests, Nanda says.

2. Black cutworms may appear, especially in patches. Moths fly up from the Gulf of Mexico and lay eggs. They often pick fields covered with green vegetation. Moths were detected in the vicinity of the Corn Watch field earlier this year. However, whether black cutworm feeding appears depends largely on weather conditions after egg laying.

3. Corn rootworms may be an issue if you didn’t plant a hybrid with GMO-rootworm protection. Rootworm larvae typically hatch in early June, give or take. You can dig for them to determine if they’re present. However, if you find them, control measures aren’t very effective.

4. Determine if seedling diseases are an issue. Especially if it’s cool and wet, pythium or other seedling blights could be a factor. Diagnosing them will help you determine why your stand isn’t perfect.

5. See if your planter closed the trench properly. “I’ve walked in cornfields early in the season in the past and found open slots which didn’t close because the soil was wet,” Nanda says. “Stands are usually affected.”

6. Plant genetics can cause a purpling effect. Some genetics tend to produce plants with a purple cast early, Nanda says. There’s no tie to yield.

7. Determine the cause of purpling. If your hybrid doesn’t tend to produce purple plants, perhaps phosphorus levels are low. When plants turn purple, there’s often not enough P in the soil.

8. Consider soil compaction as a cause of purpling. If soils are compacted and roots can’t take up phosphorus, purpling may appear.

9. Assessing stand counts now provides a baseline for future counts. If you take stand counts at or before plants are knee-high, at harvest you’ll know if stand count issues happened early or later in the year.

10. Determine if your preseason planning and planter prep paid off. “The goal is to only plant one time,” Nanda says. “Unfortunately, sometimes you have to plant again. If you determine what caused stand loss, next time you may only have to plant once.” 

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