Flint on Crops: Scout Corn for Pests, Other Problems

Western Corn Rootworm Photo: Purdue University

We are finally beginning to see fields with good stands of corn where farmers have either gotten lucky or have access to some source of intelligence that is not available to everyone. I believe we are still on track to make good yields with corn this year, but we have to begin with good management practices to keep the crop on track.

Just in case anyone has forgotten how it feels to have some kind of pest ruin a stand of healthy plants let me remind you that it is a very bad feeling indeed.

When we see those nice even rows of healthy corn plants it’s easy to get over-confident and look the other way at some other task or problem only to discover that some pest has ruined a nice field of corn. This of course can apply to any crop but for now corn is our focus.

The big idea right now is to spend time in fields at least every 3 to 4 days and walk around looking for anything that might be causing problems. Sure, you might get away with just going fishing, but I would not recommend it if you want to stay on track for good yields.

You don’t have to be an expert to spot those telltale signs of damage so park the truck and walk a while. It might be the most valuable time you have spent lately.

The first thing I noticed this week was that birds are digging up some of the shallow-planted corn seeds for a little snack. You will know this is the case by the hole that has been dug by birds such as crows and blackbirds. Of course, the seed may not be the only thing they are interested in.

There may be rootworms or the larvae or grub stage of insects such as sugarcane beetles. Don’t just settle for the idea that the bird is only digging up the seed.

Look for other signs such as holes that may have been produced by insects digging into the soil to get at the tender growing points and roots of young corn plants. This could be the beginning of a sugarcane beetle attack.

Then there may be our old nemesis the cutworm. These guys are really sneaky and tend to choose places you may not go such as the shady edges of fields where the soil may be a little damper or cooler.

Or they may go for the center of the field such as on a high spot away from the edges where you might not go if you are just stopping and spot checking. Better walk out farther into the field as well.

I have seen this happen several times when the entire center of a field would be damaged enough to require replanting while the edges were fine.

Then there are stinkbugs that arrive when the whorls of the young corn plants begin to open. They crawl down into the center of the whorl and hide so you won’t see them and then do their damage that has the potential to stunt plants and reduce the productivity of the crop.

Root worms can appear occasionally even though they are not as common as sugarcane beetles, cutworms, and stinkbugs. You will notice individual plants that seem to be just sitting there without growing.

There may be a yellow or purple leaf showing as well suggesting that part of the root system has been damaged and is not feeding its part of the above-ground portion of the plant. Dig this plant up and you may find the small white larvae having his dinner at your expense.

We can deal fairly well with cutworms and stinkbugs with foliar applied insecticides, but when you have insects such as sugarcane beetles or rootworms your chances for making a successful control application are very slim.

Several things have been tried with varying success, but the best thing is to plant seed that have been treated with one of the systemic insecticide products.

While you’re out there look for symptoms such as off color yellow, purpling, yellow streaking, yellow areas in the field, white color in the whorl, and other telltale signs that will indicate things you need to know such as nitrogen loss, deficiencies of sulfur, zinc, phosphorus, potassium, magnesium, as well as soil compaction, and other issues. I can’t cover all of this here so call if you see something that concerns you.

Thanks for your time.


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