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Search for missing plants

Keep your Bible on the nightstand and a copy of Purdue University’s Corn & Soybean Field Guide in the glove compartment. You’ll refresh your spirit, and insect and disease pests will get what’s coming to them, too.

The Field Guide is published each year as a project of the Purdue Crop Diagnostic Training and Research Center. To order, visit Learn more at www.agry.

To stay current with crop scouting conditions, check out the Purdue Pest & Crop newsletter. It’s published on the Web weekly. Find it at
. The newsletter is free.

Here’s what the Indiana Certified Crop Advisers panel suggests for early-season scouting in corn. Panel members include Gene Flaningam, Flaningam Ag Consulting LLC; Jesse Grogran with LG Seeds, Lafayette; and Dan Ritter, Purdue Extension ag educator, Newton County.

Key Points

• It’s worth it to own the Purdue Crop & Field Guide.

• Visit the Purdue University Pest & Crop newsletter on the Web.

• Look for maladies such as wireworms, slugs, cutworms and seedling blights

If we plant early and it turns cool and wet, what pests should we watch for in corn? What are signs of damage that I should look for?

Flaningam: Early-planted corn should be scouted for seed-attacking insects such as wireworm, seed corn maggot and grubs. Cool, wet soils delay germination and growth of seedlings. Blights such as pythium are also common. Things to look for include uneven emergence. Take a small spade. Dig where seedlings haven’t emerged. Examine seeds carefully for insect feeding, discoloration or decay caused by soilborne pathogens.

Grogan: There is no practical rescue treatment for wireworms and grubs. Seed-applied insecticides like Cruiser and Poncho provide a measure of protection. Wireworms attack germinating seed, so look for stand loss. Grubs feed on fine roots of germinating plants, so stunted plants or stand loss is possible. Dig up the seed to positively identify the causal agent.

Cutworms could be a problem where broadleaves were present before burndown or tillage. Make sure it’s the black cutworm. Count number found and estimate size to determine if a rescue insecticide application will help.

Ritter: I went back to a wet season, 2002, and checked Purdue Pest & Crop newsletters archived there. It mentioned wireworms, slugs, needle nematodes, seed corn maggots and seedling blights. What do you look for?

Needle nematodes: Clues are stunted, yellow plants with short, stubby roots that resemble herbicide injury. However, some species show no symptoms. To confirm nematodes, test soils.

Wireworms, seed corn maggots: After the fact, you’re looking for missing plants. Wireworms move deeper into the soil once soils warm up.

Slugs: Expect ragged leaves and silvery, slime trails on leaves. Look in areas of high residue first.

Seedling diseases: Missing plants, unthrifty or sickly-looking plants and poor emergence are possible signs. The best cure once the problem is already there is warm weather.


PURPLE PUZZLE: A good crop scout knows several causes could result in purple corn. Digging and checking roots could reveal if an insect or seedling blight is involved.

This article published in the April, 2010 edition of INDIANA PRAIRIE FARMER.

All rights reserved. Copyright Farm Progress Cos. 2010.