Solve mystery of missing corn plants
You don’t have to be Sherlock Holmes to figure out what went wrong in your cornfield. But it helps if you follow a systematic pattern and observe small details, much like the legendary, fictional character who recently returned to the big screen.
The panel of Indiana Certified Crop Advisers providing clues to solve cornfield mysteries this issue includes Betsy Bower, Ceres Solutions, west-central Indiana; Steve Dlugosz, entomologist by trade, now a crops consultant for Harvestland Co-op in east-central Indiana; and Bryan Overstreet, Purdue University Extension ag educator in Jasper and Pulaski counties in northwest Indiana.
• Seed-corn maggot and wireworm are only two possible causes of missing corn.
• Start digging down the row, looking for corn seeds.
• Some insects, such as wireworm, can survive in the soil for several years.Here’s the mystery they were asked to solve.
There are patches of corn missing in a couple of fields where I planted corn after soybeans. I applied manure on the field. Now that it’s warming up, damage seems to have stopped. How can I tell what happened? Could it happen there again?
Bower: Start digging! Dig up stunted plants, and even dig up healthy plants to look at differences. Look at seed health and coloration, check kernel hardness, and check for the presence of insects or maggots. Also check root health.
Any number of problems can be associated with missing corn. In sandier soils, missing corn is often due to high wireworm populations. In cool, wet conditions, missing corn can be due to slow germination and seed damping off. That’s a disease which can affect seedlings under wet conditions.
Seed-corn maggots can also damage corn and prevent germination. If anhydrous ammonia was applied too soon before planting, germination can also be severely affected, especially in drier areas of the field.
If you are able to find the reason why something happened in a field, oftentimes you can correct problems in succeeding years.
Dlugosz: Start by digging in the row where plants are missing. Look for missing, diseased or damaged corn kernels. Diseased plants will be dark and mushy. Insects such as seed-corn maggot or wireworm could also be the culprit. Affected kernels would show evidence of feeding or tunneling, in addition to seed rot. Most of these problems are associated with cold, wet growing conditions, especially in fields with a manure history.
Overstreet: This sounds very much like seed-corn maggot damage. It’s an early-season pest. It’s more of a problem on manured or reduced-tillage fields where there is decaying residue. Corn seed damaged by maggots may never emerge from the soil. That explains the reduced stand.
To find out if seed-corn maggots are causing the damage, dig in the furrow where plants failed to emerge. If you can find the ungerminated seed, check for either maggots or for seed damage. Note that if you planted corn in April, by early June it will be difficult to still find the damaged seed.
As far as future damage, all the damage that will occur this year is done. Replanting may be warranted in some areas if damage is bad enough.
Consider extra precautions in the future where you spread your manure. Several insecticides and seed treatments can be used as preventive seed treatments.
For more information on seed-corn maggot and replanting decisions, go to extension.entm.purdue.edu/fieldcrops
This article published in the June, 2010 edition of INDIANA PRAIRIE FARMER.